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    Angiotensin-II Receptor Blocker/ARBs and Diuretic Combinations

    BOXED WARNING

    Pregnancy

    Hydrochlorothiazide; irbesartan is classified as FDA pregnancy risk category D. When used during pregnancy, drugs that affect the renin-angiotensin system (e.g., ACE inhibitors, angiotensin II receptor antagonists) can cause fetal death or injury such as hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure and death. Oligohydramnios has also been reported; it is attributed to decreased fetal renal function and results in fetal limb contractures, craniofacial deformation, and hypoplastic lung development. Retrospective data also indicate that first trimester use of ACE inhibitors has been associated with a potential risk of birth defects. However, a much larger observational study (n = 465,754) found that the risk of birth defects was similar in infants exposed to ACE inhibitors during the first trimester, in infants exposed to other antihypertensives during the first trimester, and in those whose mothers were hypertensive but were not treated. Infants born to mothers with hypertension, either treated or untreated, had a higher risk of birth defects than those born to mothers without hypertension. The authors concluded that the presence of hypertension likely contributed to the development of birth defects rather than the use of medications. Based on the results from one large study, first trimester use of thiazide and related diuretics may increase the risk for congenital defects. In addition to malformations, other fetal risks associated with thiazide use during pregnancy include hypoglycemia, thrombocytopenia, hyponatremia, hypokalemia, and death from maternal complications. Once pregnancy is detected, every effort should be made to discontinue hydrochlorothiazide; irbesartan therapy; ultrasound examination should be performed if hydrochlorothiazide; irbesartan exposure occurs beyond the first trimester. In rare cases when another antihypertensive agent cannot be used to treat a pregnant patient, serial ultrasound examinations should be performed to assess the intraamniotic environment. Closely observe newborns with histories of in utero exposure to hydrochlorothiazide; irbesartan for hypotension, oliguria, and hyperkalemia. If oliguria occurs, blood pressure and renal perfusion support may be required, as well as exchange transfusion or dialysis to reverse hypotension and/or support decreased renal function.

    DEA CLASS

    Rx

    DESCRIPTION

    Thiazide diuretic and angiotensin II blocker; used for additive efficacy in HTN; once-daily product; irbesartan decreases potassium loss due to HCTZ.

    COMMON BRAND NAMES

    Avalide

    HOW SUPPLIED

    Avalide/Irbesartan, Hydrochlorothiazide Oral Tab: 150-12.5mg, 300-12.5mg

    DOSAGE & INDICATIONS

    For the treatment of hypertension in patients who do not respond to monotherapy and/or as initial therapy in patients likely to need multiple drugs to achieve blood pressure goals.
    Individualize the dosage by titration of the separate components. If the optimal dose corresponds to the ratio contained in the combination formulation, this product can be used for convenient dosing.
    Oral dosage
    Adults

    When blood pressure is not controlled with irbesartan, the initial dosage is 1 tablet Avalide 150—12.5 mg (irbesartan and HCTZ) PO once daily. Avalide is not intended as first-line therapy, since individual titration of the separate components is needed. Adjust dosage based on clinical response. Antihypertensive effects are stabilized after 2—4 weeks. May increase the dosage to one tablet Avalide 300—12.5 mg PO once daily. Maximum dose is 1 tablet Avalide 300—25 mg PO once daily. Correct volume and/or sodium depletion prior to administration.

    Geriatric

    See adult dosage. Greater sensitivity to irbesartan or hydrochlorothiazide is possible. Adjust dosage based on clinical response.

    MAXIMUM DOSAGE

    Adults

    300 mg/day PO irbesartan and 25 mg/day PO hydrochlorothiazide.

    Elderly

    300 mg/day PO irbesartan and 25 mg/day PO hydrochlorothiazide.

    Adolescents

    Safety and efficacy have not been established.

    Children

    Safety and efficacy have not been established.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Hydrochlorothiazide: HCTZ should be used with caution in patients with hepatic disease since alterations of fluid and electrolyte balance may precipitate hepatic coma. 
    Irbesartan: No irbesartan dosage adjustment is needed in patients with mild-moderate hepatic disease; however, the drug has not been studied in patients with severe hepatic disease.

    Renal Impairment

    CrCl > 30 mL/min: No dosage adjustment is necessary.
    CrCl <= 30 mL/min: Combination products containing hydrochlorothiazide are not recommended. Thiazide diuretics are not effective in this setting.
     
    Intermittent hemodialysis
    Combination therapy with hydrochlorothiazide is not recommended in patients with CrCl <= 30 mL/min. Thiazide diuretics are generally not effective in this setting.

    ADMINISTRATION

    Oral Administration

    Hydrochlorothiazide; irbesartan may be administered without regard to meals.

    STORAGE

    Avalide:
    - Store at 77 degrees F; excursions permitted to 59-86 degrees F

    CONTRAINDICATIONS / PRECAUTIONS

    General Information

    Thiazide diuretics such as hydrochlorothiazide have been associated with a slight increase in serum cholesterol and triglyceride concentrations. Data from long-term studies, however, suggest diuretic-induced cholesterol changes are not clinically significant and do not contribute to coronary heart disease risk.

    Asthma, penicillin hypersensitivity, sulfonamide hypersensitivity, thiazide diuretic hypersensitivity

    Thiazide diuretics are contraindicated in patients with known thiazide diuretic hypersensitivity. According to the manufacturer, hydrochlorothiazide is specifically contraindicated in patients with sulfonamide hypersensitivity. Hypersensitivity reactions may occur in patients with or without a history of allergy or bronchial asthma; however, reactions are more likely to occur in patients with such history. Although thiazide diuretics are sulfonamide derivatives, sulfonamide cross-sensitivity has been rarely documented. Until further data are available, thiazide diuretics should be used with caution in patients with sulfonamide hypersensitivity. Thiazide diuretics do not contain the N4-aromatic amine or the N1-substituent which are present in sulfonamide antibiotics.[32380] Non-arylamine sulfonamide derivatives, such as thiazide diuretics, have been proposed to have a lower risk of allergic reactions in patients with sulfonamide allergy, presumably due to lack of an arylamine group at the N4 position (a proposed structural site of action for sulfonamide allergy). One large retrospective cohort study has reported that in patients with the presence of an allergic reaction after exposure to a sulfonamide antibiotic, 9.9% had an allergic reaction after receiving a non-antibiotic sulfonamide derivative, while in patients who lacked an allergic reaction after sulfonamide antibiotic exposure, 1.6% had an allergic reaction after administration of a non-antibiotic sulfonamide derivative (adjusted odds ratio 2.8; 95% CI, 2.1—3.7).[32382] A causal relationship between sulfonamide hypersensitivity and allergic reactions with non-arylamine sulfonamide derivatives has not been definitively established and remains controversial. In general, patients with a documented sulfonamide allergy are considered to be predisposed for development of allergic drug reactions. Also, patients with a history of sulfonamide hypersensitivity or penicillin hypersensitivity who receive hydrochlorothiazide may also be at increased risk for the development of an idiosyncratic reaction resulting in transient myopia and acute angle-closure glaucoma. Discontinue hydrochlorothiazide promptly if this reaction occurs.

    Anuria, heart failure, renal artery stenosis, renal disease, renal failure, renal impairment

    Hydrochlorothiazide; irbesartan is contraindicated in patients with anuria since thiazide diuretics are considered ineffective when the creatinine clearance is less than 30 mL/minute. Hydrochlorothiazide should be used cautiously in patients with renal disease resulting in severe renal impairment or renal failure because the drug decreases the glomerular filtration rate and may precipitate azotemia in these patients. Irbesartan should be used with caution in patients whose renal function is critically dependent on the activity of the renin-angiotensin-aldosterone system (RAS) (e.g., patients with heart failure). Angiotensin converting enzyme inhibitors (ACEIs) and angiotensin II receptor antagonists affect the RAS system and have caused increases in serum creatinine and renal failure in susceptible individuals. Although serum creatinine returns to baseline or stabilizes in most patients with continued use, oliguria, progressive azotemia, and rarely, acute renal failure have occurred. In addition, ACEIs have been associated with azotemia in patients with unilateral or bilateral renal artery stenosis. Although irbesartan has not been studied in renal artery stenosis, similar effects to the ACEIs might be anticipated due to angiotensin II blockade. Renal function should be monitored in patients receiving hydrochlorothiazide; irbesartan.

    Hepatic disease

    Although the pharmacokinetics of irbesartan were not altered in a study of 10 patients with mild to moderate hepatic cirrhosis, approximately 80% of irbesartan is eliminated by the biliary route as irbesartan or irbesartan glucuronide. Irbesartan has not been studied in patients with severe liver disease. The manufacturer recommends that no initial dosage adjustment of irbesartan is necessary in patients with hepatic insufficiency; however until more data are available, close monitoring is warranted in patients with liver disease. Dosage increases should be made cautiously. Hydrochlorothiazide should be used with caution in patients with hepatic disease since minor alterations of fluid and electrolyte balance may precipitate hepatic coma.

    Hypotension, hypovolemia, orthostatic hypotension, sympathectomy, syncope

    Hypovolemia increases the risk of symptomatic hypotension during therapy. Hydrochlorothiazide; irbesartan should be used with great care in patients with signs of hypotension. Volume- or sodium-depleted patients (e.g., those receiving hemodialysis or aggressive diuretic therapy) should have these conditions corrected prior to using hydrochlorothiazide; irbesartan to avoid possible symptomatic hypotension. Orthostatic hypotension may occur during treatment with thiazide diuretics. Orthostatic hypotension can be exacerbated by concurrent use of alcohol, narcotics, or antihypertensive drugs. Excessive hypotension during thiazide diuretic therapy can result in syncope. An increased risk of falls has been reported for elderly patients receiving thiazide diuretics. In addition, the antihypertensive effects of thiazides may be enhanced in other patients predisposed for orthostatic hypotension, including the post-sympathectomy patient.

    ACE-inhibitor induced angioedema, angioedema

    Anaphylactic reactions (anaphylactoid reactions) and angioedema have been reported with angiotensin II receptor antagonists. Theoretically, angiotensin II receptor antagonists should be less likely than angiotensin converting enzyme inhibitors (ACEIs) to precipitate angioedema because angiotensin II receptor antagonists do not cause accumulation of kinins. However, angioedema (swelling of lips and eyelids, facial rash) has been rarely reported in patients receiving angiotensin II receptor antagonists, including in patients with a prior history of ACE-inhibitor induced angioedema. While angiotensin II receptor antagonists have been suggested as potential alternatives to ACE inhibitors for patients who experience angioedema due to a lower frequency of associated angioedema , the safety of angiotensin II receptor antagonists in patients with a prior history of ACE-inhibitor induced angioedema has not been definitively established. It is prudent to use substantial caution when prescribing irbesartan in patients with a history of ACE-inhibitor induced angioedema. Some authors have recommended that angiotensin II receptor antagonists should be avoided in patients with a history of angioedema, especially those with ACE-inhibitor induced angioedema.

    Surgery

    In patients undergoing major surgery or during anesthesia with agents that lower blood pressure, irbesartan may enhance hypotensive effects via angiotensin II blockade. Therefore, hydrochlorothiazide; irbesartan should be used with caution prior to surgery. If hypotension occurs during surgery and/or anesthesia and is considered to be due to blockade of angiotensin II formation, it can be corrected by volume expansion.

    Pregnancy

    Hydrochlorothiazide; irbesartan is classified as FDA pregnancy risk category D. When used during pregnancy, drugs that affect the renin-angiotensin system (e.g., ACE inhibitors, angiotensin II receptor antagonists) can cause fetal death or injury such as hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure and death. Oligohydramnios has also been reported; it is attributed to decreased fetal renal function and results in fetal limb contractures, craniofacial deformation, and hypoplastic lung development. Retrospective data also indicate that first trimester use of ACE inhibitors has been associated with a potential risk of birth defects. However, a much larger observational study (n = 465,754) found that the risk of birth defects was similar in infants exposed to ACE inhibitors during the first trimester, in infants exposed to other antihypertensives during the first trimester, and in those whose mothers were hypertensive but were not treated. Infants born to mothers with hypertension, either treated or untreated, had a higher risk of birth defects than those born to mothers without hypertension. The authors concluded that the presence of hypertension likely contributed to the development of birth defects rather than the use of medications. Based on the results from one large study, first trimester use of thiazide and related diuretics may increase the risk for congenital defects. In addition to malformations, other fetal risks associated with thiazide use during pregnancy include hypoglycemia, thrombocytopenia, hyponatremia, hypokalemia, and death from maternal complications. Once pregnancy is detected, every effort should be made to discontinue hydrochlorothiazide; irbesartan therapy; ultrasound examination should be performed if hydrochlorothiazide; irbesartan exposure occurs beyond the first trimester. In rare cases when another antihypertensive agent cannot be used to treat a pregnant patient, serial ultrasound examinations should be performed to assess the intraamniotic environment. Closely observe newborns with histories of in utero exposure to hydrochlorothiazide; irbesartan for hypotension, oliguria, and hyperkalemia. If oliguria occurs, blood pressure and renal perfusion support may be required, as well as exchange transfusion or dialysis to reverse hypotension and/or support decreased renal function.

    Breast-feeding

    According to the manufacturer, because of the potential for adverse effects on the nursing infant, a decision should be made to discontinue breast-feeding or discontinue irbesartan; hydrochlorothiazide therapy. It is not known whether irbesartan is excreted into human milk. Hydrochlorothiazide has been detected in human breast milk. The American Academy of Pediatrics (AAP) has not evaluated the use of irbesartan in breast-feeding mothers; however, the AAP does consider hydrochlorothiazide as usually compatible with breast-feeding. In addition, the ACE inhibitors captopril and enalapril are classified by the AAP as usually compatible with breast-feeding and may represent preferable alternatives in some patients. Benazepril and quinapril are excreted in human breast milk in very small quantities ; therefore, a clinically significant risk to a breast-feeding infant is not expected. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    Children

    Safety and effectiveness of hydrochlorothiazide; irbesartan have not been established in children.

    Electrolyte imbalance, hypercalcemia, hyperkalemia, hypokalemia, hypomagnesemia, hyponatremia

    Patients with pre-existing significant hyponatremia, hyperkalemia, hypokalemia, hypomagnesemia, and/or hypercalcemia should have their electrolyte imbalances corrected before hydrochlorothiazide; irbesartan is initiated. Thiazide diuretics such as hydrochlorothiazide have been shown to increase the urinary excretion of magnesium and decrease urinary calcium excretion. Thiazides may worsen dilutional hyponatremia, especially in elderly individuals. Hydrochlorothiazide; irbesartan may reduce, elevate or leave potassium levels unchanged in individual patients; although hyperkalemia is uncommon. All patients should be monitored closely for clinical signs of fluid or electrolyte imbalance.

    Diabetes mellitus, hyperglycemia

    Hyperglycemia or impaired glucose tolerance can occur during hydrochlorothiazide therapy. In patients with diabetes mellitus who are receiving hydrochlorothiazide; irbesartan, blood glucose levels should be monitored frequently. Adjustment of insulin and/or oral hypoglycemic agents may be required.

    Pancreatitis

    Thiazide diuretics have been reported to cause pancreatitis. Hydrochlorothiazide; irbesartan should be used with caution in patients with a history of pancreatitis.

    Gout, hyperuricemia

    Hydrochlorothiazide; irbesartan should be administered cautiously to patients with gout or hyperuricemia since thiazide diuretics such as hydrochlorothiazide have been reported to reduce the clearance of uric acid.

    Systemic lupus erythematosus (SLE)

    Hydrochlorothiazide has been reported to activate or exacerbate systemic lupus erythematosus (SLE).

    Sunlight (UV) exposure

    Photosensitivity has been reported with thiazide diuretics.[30713] Patients should avoid excessive sunlight (UV) exposure and hydrochlorothiazide; irbesartan therapy should be discontinued if phototoxicity occurs.

    Geriatric

    No overall differences in effectiveness were observed between geriatric patients and younger adult patients during clinical trials of irbesartan; hydrochlorothiazide. Greater sensitivity to the usual dosage of hydrochlorothiazide or irbesartan may occur in some older adult patients, and care should be taken in initial dose selection for the geriatric adult, usually starting at the low end of the usual adult dose range. Thiazides may worsen dilutional hyponatremia, especially in geriatric individuals. An increased risk of falls has been reported for older adult patients receiving thiazide diuretics. Patients receiving diuretics should be monitored for clinical signs of acid/base, fluid, or electrolyte imbalances. According to the Beers Criteria, diuretics such as hydrochlorothiazide are considered potentially inappropriate medications (PIMs) in geriatric patients and should be used with caution due to the potential for causing or exacerbating SIADH or hyponatremia; sodium levels should be closely monitored when starting or changing dosages of diuretics in older adults.

    ADVERSE REACTIONS

    Severe

    angioedema / Rapid / 0-1.0
    hyperkalemia / Delayed / 0-1.0
    serious hypersensitivity reactions or anaphylaxis / Rapid / Incidence not known
    anaphylactic shock / Rapid / Incidence not known
    azotemia / Delayed / Incidence not known
    exfoliative dermatitis / Delayed / Incidence not known
    Stevens-Johnson syndrome / Delayed / Incidence not known
    toxic epidermal necrolysis / Delayed / Incidence not known
    hemolytic anemia / Delayed / Incidence not known
    agranulocytosis / Delayed / Incidence not known
    aplastic anemia / Delayed / Incidence not known
    ocular hypertension / Delayed / Incidence not known
    rhabdomyolysis / Delayed / Incidence not known
    teratogenesis / Delayed / Incidence not known
    pancreatitis / Delayed / Incidence not known

    Moderate

    hypokalemia / Delayed / 7.5-7.5
    chest pain (unspecified) / Early / 2.0-2.0
    hypotension / Rapid / 1.0-1.0
    impotence (erectile dysfunction) / Delayed / 0-1.0
    hypovolemia / Early / Incidence not known
    orthostatic hypotension / Delayed / Incidence not known
    hepatitis / Delayed / Incidence not known
    jaundice / Delayed / Incidence not known
    elevated hepatic enzymes / Delayed / Incidence not known
    hyperbilirubinemia / Delayed / Incidence not known
    hyperglycemia / Delayed / Incidence not known
    leukopenia / Delayed / Incidence not known
    thrombocytopenia / Delayed / Incidence not known
    gout / Delayed / Incidence not known
    nephrolithiasis / Delayed / Incidence not known
    hyperuricemia / Delayed / Incidence not known
    hypercalcemia / Delayed / Incidence not known
    hypomagnesemia / Delayed / Incidence not known
    hypercholesterolemia / Delayed / Incidence not known
    hypertriglyceridemia / Delayed / Incidence not known
    xanthopsia / Delayed / Incidence not known
    myopia / Delayed / Incidence not known
    blurred vision / Early / Incidence not known
    conjunctivitis / Delayed / Incidence not known
    sialadenitis / Delayed / Incidence not known

    Mild

    dizziness / Early / 8.0-8.0
    fatigue / Early / 6.0-6.0
    musculoskeletal pain / Early / 6.0-6.0
    vomiting / Early / 3.0-3.0
    nausea / Early / 3.0-3.0
    dyspepsia / Early / 2.0-2.0
    abdominal pain / Early / 2.0-2.0
    cough / Delayed / 1.0
    tinnitus / Delayed / Incidence not known
    syncope / Early / Incidence not known
    alopecia / Delayed / Incidence not known
    urticaria / Rapid / Incidence not known
    photosensitivity / Delayed / Incidence not known
    muscle cramps / Delayed / Incidence not known
    fever / Early / Incidence not known

    DRUG INTERACTIONS

    Acarbose: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Acetaminophen; Butalbital; Caffeine; Codeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Acetaminophen; Codeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Acetaminophen; Dichloralphenazone; Isometheptene: (Major) Isometheptene has sympathomimetic properties. Patients taking antihypertensive agents may need to have their therapy modified. Careful blood pressure monitoring is recommended. (Moderate) Isometheptene has sympathomimetic properties. Patients taking antihypertensive agents may need to have their therapy modified. Careful blood pressure monitoring is recommended.
    Acetaminophen; Guaifenesin; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Acetaminophen; Hydrocodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Acetaminophen; Oxycodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Acetaminophen; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Acetazolamide: (Moderate) Acetazolamide promotes electrolyte excretion including hydrogen ions, sodium, and potassium. It can enhance the sodium depleting effects of other diuretics when used concurrently. Pre-existing hypokalemia and hyperuricemia can also be potentiated by carbonic anhydrase inhibitors. Monitor serum potassium to determine the need for potassium supplementation and alteration in drug therapy.
    Acetohexamide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Acrivastine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Albiglutide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Albuterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Albuterol; Ipratropium: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Aldesleukin, IL-2: (Moderate) Angiotensin II receptor antagonists may potentiate the hypotension seen with aldesleukin, IL 2. (Moderate) Thiazide diuretics may potentiate the hypotension seen with aldesleukin, IL 2.
    Alemtuzumab: (Moderate) Alemtuzumab may cause hypotension. Careful monitoring of blood pressure and hypotensive symptoms is recommended especially in patients with ischemic heart disease and in patients on antihypertensive agents.
    Alendronate; Cholecalciferol: (Major) Dose adjustment of vitamin D or vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D or vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
    Alfentanil: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Aliskiren: (Major) Most patients receiving the combination of two renin-angiotensin-aldosterone system (RAAS) inhibitors, such as angiotensin II receptor antagonists (ARBs) and aliskiren do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of RAAS inhibitors particularly in patients with CrCl < 60 mL/min. Closely monitor blood pressure, renal function, and electrolytes if aliskiren is combined with another RAAS inhibitor. Aliskiren-containing products are contraindicated in combination with ARBs in patients with diabetes mellitus. In the ALTITUDE trial, patients with type 2 diabetes and renal impairment, a population at high risk for cardiovascular and renal events, were given aliskiren in addition to ACE inhibitors or ARBs. The trial was stopped early because aliskiren was associated with an increased risk of non-fatal stroke, renal complications, hyperkalemia, and hypotension. In the Veterans Affairs Nephropathy in Diabetes (VA NEPHRON-D) trial, no additional benefit over monotherapy was seen in patients receiving the combination of losartan and lisinopril compared to monotherapy; however, there was an increased incidence of hyperkalemia and acute renal injury.
    Aliskiren; Amlodipine: (Major) Most patients receiving the combination of two renin-angiotensin-aldosterone system (RAAS) inhibitors, such as angiotensin II receptor antagonists (ARBs) and aliskiren do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of RAAS inhibitors particularly in patients with CrCl < 60 mL/min. Closely monitor blood pressure, renal function, and electrolytes if aliskiren is combined with another RAAS inhibitor. Aliskiren-containing products are contraindicated in combination with ARBs in patients with diabetes mellitus. In the ALTITUDE trial, patients with type 2 diabetes and renal impairment, a population at high risk for cardiovascular and renal events, were given aliskiren in addition to ACE inhibitors or ARBs. The trial was stopped early because aliskiren was associated with an increased risk of non-fatal stroke, renal complications, hyperkalemia, and hypotension. In the Veterans Affairs Nephropathy in Diabetes (VA NEPHRON-D) trial, no additional benefit over monotherapy was seen in patients receiving the combination of losartan and lisinopril compared to monotherapy; however, there was an increased incidence of hyperkalemia and acute renal injury.
    Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Major) Most patients receiving the combination of two renin-angiotensin-aldosterone system (RAAS) inhibitors, such as angiotensin II receptor antagonists (ARBs) and aliskiren do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of RAAS inhibitors particularly in patients with CrCl < 60 mL/min. Closely monitor blood pressure, renal function, and electrolytes if aliskiren is combined with another RAAS inhibitor. Aliskiren-containing products are contraindicated in combination with ARBs in patients with diabetes mellitus. In the ALTITUDE trial, patients with type 2 diabetes and renal impairment, a population at high risk for cardiovascular and renal events, were given aliskiren in addition to ACE inhibitors or ARBs. The trial was stopped early because aliskiren was associated with an increased risk of non-fatal stroke, renal complications, hyperkalemia, and hypotension. In the Veterans Affairs Nephropathy in Diabetes (VA NEPHRON-D) trial, no additional benefit over monotherapy was seen in patients receiving the combination of losartan and lisinopril compared to monotherapy; however, there was an increased incidence of hyperkalemia and acute renal injury.
    Aliskiren; Hydrochlorothiazide, HCTZ: (Major) Most patients receiving the combination of two renin-angiotensin-aldosterone system (RAAS) inhibitors, such as angiotensin II receptor antagonists (ARBs) and aliskiren do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of RAAS inhibitors particularly in patients with CrCl < 60 mL/min. Closely monitor blood pressure, renal function, and electrolytes if aliskiren is combined with another RAAS inhibitor. Aliskiren-containing products are contraindicated in combination with ARBs in patients with diabetes mellitus. In the ALTITUDE trial, patients with type 2 diabetes and renal impairment, a population at high risk for cardiovascular and renal events, were given aliskiren in addition to ACE inhibitors or ARBs. The trial was stopped early because aliskiren was associated with an increased risk of non-fatal stroke, renal complications, hyperkalemia, and hypotension. In the Veterans Affairs Nephropathy in Diabetes (VA NEPHRON-D) trial, no additional benefit over monotherapy was seen in patients receiving the combination of losartan and lisinopril compared to monotherapy; however, there was an increased incidence of hyperkalemia and acute renal injury.
    Aliskiren; Valsartan: (Major) Most patients receiving the combination of two renin-angiotensin-aldosterone system (RAAS) inhibitors, such as angiotensin II receptor antagonists (ARBs) and aliskiren do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of RAAS inhibitors particularly in patients with CrCl < 60 mL/min. Closely monitor blood pressure, renal function, and electrolytes if aliskiren is combined with another RAAS inhibitor. Aliskiren-containing products are contraindicated in combination with ARBs in patients with diabetes mellitus. In the ALTITUDE trial, patients with type 2 diabetes and renal impairment, a population at high risk for cardiovascular and renal events, were given aliskiren in addition to ACE inhibitors or ARBs. The trial was stopped early because aliskiren was associated with an increased risk of non-fatal stroke, renal complications, hyperkalemia, and hypotension. In the Veterans Affairs Nephropathy in Diabetes (VA NEPHRON-D) trial, no additional benefit over monotherapy was seen in patients receiving the combination of losartan and lisinopril compared to monotherapy; however, there was an increased incidence of hyperkalemia and acute renal injury.
    Alkalinizing Agents: (Major) Products containing a potassium salt, including citric acid; potassium citrate; sodium citrate, should be used with caution in patients taking drugs that may increase serum potassium concentrations, such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients.
    Allopurinol: (Moderate) The occurrence of certain hypersensitivity reactions may be increased in patients with renal impairment who receive allopurinol and thiazide diuretics in combination. The precise mechanism for such events is unclear but likely immune-mediated and may be related to an effect of oxypurinol; elevated oxypurinol concentrations appear to be associated with hypersensitivity reactions; decreased clearance of this metabolite may occur with renal impairment and with the concurrent use of thiazide diuretics. Severe skin reactions include exfoliative dermatitis, toxic epidermal necrolysis and Steven's Johnson syndrome; some reactions have been fatal. In addition, thiazide diuretics, like hydrochlorothiazide, can cause hyperuricemia. Since thiazides reduce the clearance of uric acid, patients with gout or hyperuricemia may have exacerbations of their disease.
    Alogliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Alogliptin; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Alogliptin; Pioglitazone: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Alpha-glucosidase Inhibitors: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Alprostadil: (Minor) The concomitant use of systemic alprostadil injection and antihypertensive agents, such as angiotensin II receptor antagonists (angiotensin receptor blockers, or ARBs), may cause additive hypotension. Caution is advised with this combination. Systemic drug interactions with the urethral suppository (MUSE) or alprostadil intracavernous injection are unlikely in most patients because low or undetectable amounts of the drug are found in the peripheral venous circulation following administration. In those men with significant corpora cavernosa venous leakage, hypotension might be more likely. Use caution with in-clinic dosing for erectile dysfunction (ED) and monitor for the effects on blood pressure. However, in clinical trials with alprostadil intracavernous injection, anti-hypertensive agents had no apparent effect on the safety and efficacy of alprostadil. (Minor) The concomitant use of systemic alprostadil injection and antihypertensive agents, such as thiazide diuretics, may cause additive hypotension. Caution is advised with this combination. Systemic drug interactions with the urethral suppository (MUSE) or alprostadil intracavernous injection are unlikely in most patients because low or undetectable amounts of the drug are found in the peripheral venous circulation following administration. In those men with significant corpora cavernosa venous leakage, hypotension might be more likely. Use caution with in-clinic dosing for erectile dysfunction (ED) and monitor for the effects on blood pressure. In addition, the presence of medications in the circulation that attenuate erectile function may influence the response to alprostadil. However, in clinical trials with alprostadil intracavernous injection, anti-hypertensive agents had no apparent effect on the safety and efficacy of alprostadil.
    Amifostine: (Major) Patients receiving angiotensin II receptor antagonists should be closely monitored during amifostine infusions due to additive effects. Patients receiving amifostine at doses recommended for chemotherapy should have antihypertensive therapy interrupted 24 hours preceding administration of amifostine. If the antihypertensive cannot be stopped, patients should not receive amifostine. (Major) Patients receiving antihypertensive agents should be closely monitored during amifostine infusions due to additive effects. If possible, patients should not take their antihypertensive medication 24 hours before receiving amifostine. Patients who can not stop their antihypertensive agents should not receive amifostine or be closely monitored during the infusion and, possibly, given lower doses.
    Amiloride: (Major) Potassium-sparing diuretics, such as amiloride, should be used with caution in patients taking drugs that may increase serum potassium levels such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients.
    Amiloride; Hydrochlorothiazide, HCTZ: (Major) Potassium-sparing diuretics, such as amiloride, should be used with caution in patients taking drugs that may increase serum potassium levels such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients.
    Amiodarone: (Major) Since antiarrhythmic drugs may be ineffective or may be arrhythmogenic in patients with hypokalemia, any potassium or magnesium deficiency should be corrected before instituting and during amiodarone therapy. Use caution when coadministering amiodarone with drugs which may induce hypokalemia and, or hypomagnesemia including thiazide diuretics.
    Amlodipine; Benazepril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Amobarbital: (Moderate) Concurrent use of amobarbital with antihypertensive agents may lead to hypotension. Monitor for decreases in blood pressure during times of coadministration.
    Amoxicillin; Clarithromycin; Lansoprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Amoxicillin; Clarithromycin; Omeprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Amphetamine; Dextroamphetamine Salts: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents, such as angiotensin II receptor antagonists. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed. (Moderate) Thiazides may increase blood levels and therefore potentiate the actions of amphetamines. Thiazide diuretics may increase urinary pH, acting as a urinary alkalinizer, thus reducing urinary excretion and increasing blood concentrations of the amphetamine. Co-administration of amphetamines and urinary alkalinizing agents should be avoided if possible. If needed, monitor for common amphetamine side effects, including decreased appetite, anxiety, dizziness, dry mouth, irritability, insomnia, nausea, increased blood pressure or increased heart rate. Amphetamines increase both systolic and diastolic blood pressure. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
    Amphotericin B cholesteryl sulfate complex (ABCD): (Moderate) The risk of developing severe hypokalemia can be increased when amphotericin B is coadministered with thiazide diuretics. Monitoring serum potassium levels and cardiac function is advised, and potassium supplementation may be required.
    Amphotericin B lipid complex (ABLC): (Moderate) The risk of developing severe hypokalemia can be increased when amphotericin B is coadministered with thiazide diuretics. Monitoring serum potassium levels and cardiac function is advised, and potassium supplementation may be required.
    Amphotericin B liposomal (LAmB): (Moderate) The risk of developing severe hypokalemia can be increased when amphotericin B is coadministered with thiazide diuretics. Monitoring serum potassium levels and cardiac function is advised, and potassium supplementation may be required.
    Amphotericin B: (Moderate) The risk of developing severe hypokalemia can be increased when amphotericin B is coadministered with thiazide diuretics. Monitoring serum potassium levels and cardiac function is advised, and potassium supplementation may be required.
    Amyl Nitrite: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary. (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
    Angiotensin II: (Moderate) Angiotensin II receptor antagonists may decrease the response to angiotensin II.
    Angiotensin-converting enzyme inhibitors: (Major) Most patients receiving the combination of two renin-angiotensin-aldosterone system (RAAS) inhibitors, such as angiotensin-converting enzyme inhibitors (ACE inhibitors) and angiotensin II receptor antagonists (ARBs) do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of these drugs together. Closely monitor blood pressure, renal function, and electrolytes. Combination therapy has been associated with an increased risk of diarrhea, hypotension, syncope, hyperkalemia, and renal dysfunction resulting in dialysis, doubling of serum creatinine, and death. In the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET), the combination of ramipril 10 mg/day and telmisartan 80 mg/day did not provide a significant benefit in the prevention of death from cardiovascular causes, myocardial infarction, stroke, or hospitalization for heart failure compared to ramipril alone. There was, however, a significantly increased rate of renal dysfunction associated with combination therapy (13.5%) compared to ramipril (10.2%) or telmisartan (10.6%) alone and a significantly increased rate of hyperkalemia with combination therapy compared to ramipril (5.6% vs. 3.3%; p<0.001). Additionally, there was a significantly higher number of patients who discontinued therapy due to adverse reactions, including hypotensive symptoms (4.8% vs. 1.7%; p<0.001), syncope (0.3% vs. 0.2%; p=0.03), diarrhea (0.5% vs. 0.1%; p<0.001), and renal impairment (1.1% vs. 0.7%; p<0.001), from combination therapy compared to ramipril alone. In a separate analysis of the ONTARGET renal outcomes, the rate of the composite primary renal outcome of dialysis, doubling of serum creatinine, and death was similar with ramipril and telmisartan alone (13.5% vs. 13.6%, respectively), but was significantly higher with combination therapy (14.5%) compared to ramipril (p=0.037). In the CHARM-Added program, the combination of candesartan and an ACE-inhibitor resulted in an increased incidence of hypotension (22.6% vs. 13.8%), renal dysfunction (15% vs. 9%), and hyperkalemia (9.5% vs. 3.5%) compared to placebo combined with an ACE inhibitor. In the Veterans Affairs Nephropathy in Diabetes (VA NEPHRON-D) trial, no additional benefit over monotherapy was seen in patients receiving the combination of losartan and lisinopril compared to monotherapy; however, there was an increased incidence of hyperkalemia and acute renal injury. Patients receiving concomitant therapy with ACE inhibitors and ARBs should be closely monitored for renal dysfunction, hypotension, and hyperkalemia. (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Anticholinergics: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Apomorphine: (Moderate) Patients receiving apomorphine may experience orthostatic hypotension, hypotension, and/or syncope. Extreme caution should be exercised if apomorphine is used concurrently with antihypertensive agents, or vasodilators such as nitrates.
    Apraclonidine: (Minor) Alpha blockers as a class may reduce heart rate and blood pressure. While no specific drug interactions have been identified with systemic agents and apraclonidine during clinical trials, it is theoretically possible that additive blood pressure reductions could occur when apraclonidine is combined with the use of antihypertensive agents. Patients using cardiovascular drugs concomitantly with apraclonidine should have their pulse and blood pressure monitored periodically.
    Arformoterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Aripiprazole: (Minor) Aripiprazole may enhance the hypotensive effects of antihypertensive agents.
    Arsenic Trioxide: (Major) Avoid concomitant use of arsenic trioxide with thiazide diuretics. Electrolyte abnormalities, such as hypokalemia and hypomagnesemia, may increase the risk for QT prolongation and torsade de pointes. Monitor electrocardiograms and serum electrolytes more frequently if concurrent use cannot be avoided.
    Articaine; Epinephrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives such as metolazone when administered concomitantly.
    Asenapine: (Moderate) Secondary to alpha-blockade, asenapine can produce vasodilation that may result in additive effects during concurrent use of antihypertensive agents. The potential reduction in blood pressure can precipitate orthostatic hypotension and associated dizziness, tachycardia, and syncope. If concurrent use of asenapine and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position. Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Aspirin, ASA; Omeprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Aspirin, ASA; Oxycodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Atracurium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Atropine: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) Thiazide diuretics may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Atropine; Difenoxin: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Atropine; Diphenoxylate: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Atropine; Edrophonium: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Atropine; Hyoscyamine; Phenobarbital; Scopolamine: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Baclofen: (Moderate) Baclofen has been associated with hypotension. Concurrent use with baclofen and antihypertensive agents may result in additive hypotension. Dosage adjustments of the antihypertensive medication may be required.
    Barbiturates: (Moderate) Barbiturates may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Belladonna Alkaloids; Ergotamine; Phenobarbital: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Belladonna; Opium: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Benazepril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) Thiazide diuretics may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Benzphetamine: (Moderate) Benzphetamine can increase both systolic and diastolic blood pressure and may counteract the activity of angiotensin II receptor antagonists. This represents a pharmacodynamic, and not a pharmacokinetic, interaction. Close monitoring of blood pressure, especially in patients who are taking antihypertensive agents, may be needed. (Moderate) Thiazides may increase blood levels and therefore potentiate the actions of amphetamines. Thiazide diuretics may increase urinary pH, acting as a urinary alkalinizer, thus reducing urinary excretion and increasing blood concentrations of the amphetamine. Co-administration of amphetamines and urinary alkalinizing agents should be avoided if possible. If needed, monitor for common amphetamine side effects, including decreased appetite, anxiety, dizziness, dry mouth, irritability, insomnia, nausea, increased blood pressure or increased heart rate. Amphetamines increase both systolic and diastolic blood pressure. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
    Benztropine: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Beta-agonists: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Bortezomib: (Moderate) Patients on antihypertensive agents receiving bortezomib treatment may require close monitoring of their blood pressure and dosage adjustment of their medication. During clinical trials of bortezomib, hypotension was reported in roughly 12 percent of patients.
    Bosentan: (Moderate) Although no specific interactions have been documented, bosentan has vasodilatory effects and may contribute additive hypotensive effects when given with angiotensin II receptor antagonists. Losartan has no effect on plasma concentrations of bosentan. However, bosentan may theoretically induce the metabolism of losartan via CYP2C9 isoenzymes (clinical significance unknown). (Moderate) Although no specific interactions have been documented, bosentan has vasodilatory effects and may contribute additive hypotensive effects when given with diuretics.
    Brexpiprazole: (Moderate) Due to brexpiprazole's antagonism at alpha 1-adrenergic receptors, the drug may enhance the hypotensive effects of alpha-blockers and other antihypertensive agents.
    Brompheniramine; Carbetapentane; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Brompheniramine; Guaifenesin; Hydrocodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Brompheniramine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Budesonide; Formoterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Buprenorphine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Buprenorphine; Naloxone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Cabergoline: (Minor) Cabergoline has minimal affinity for adrenergic receptors; however, it has been associated with hypotension in some instances. Cabergoline should be used cautiously in those receiving antihypertensive agents.
    Calcium Phosphate, Supersaturated: (Moderate) Concomitant use of medicines with potential to alter renal perfusion or function such as angiotensin II receptor antagonists, may increase the risk of acute phosphate nephropathy in patients taking sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous. (Moderate) Concomitant use of medicines with potential to alter renal perfusion or function such as diuretics, may increase the risk of acute phosphate nephropathy in patients taking sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous.
    Calcium: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Calcium; Vitamin D: (Major) Dose adjustment of vitamin D or vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D or vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
    Canagliflozin: (Moderate) When canagliflozin is initiated in patients already receiving diuretics, symptomatic hypotension can occur. Patients with impaired renal function (eGFR < 60 ml/min/1.73 m2), low systolic blood pressure, or who are elderly may also be at a greater risk. Before initiating canagliflozin in patients with one or more of these characteristics, volume status should be assessed and corrected. Monitor for signs and symptoms after initiating therapy. In addition, thiazide diuretics, can also decrease the hypoglycemic effects of antidiabetic agents by producing an increase in blood glucose concentrations. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. Thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients receiving canagliflozin should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Canagliflozin; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) When canagliflozin is initiated in patients already receiving diuretics, symptomatic hypotension can occur. Patients with impaired renal function (eGFR < 60 ml/min/1.73 m2), low systolic blood pressure, or who are elderly may also be at a greater risk. Before initiating canagliflozin in patients with one or more of these characteristics, volume status should be assessed and corrected. Monitor for signs and symptoms after initiating therapy. In addition, thiazide diuretics, can also decrease the hypoglycemic effects of antidiabetic agents by producing an increase in blood glucose concentrations. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. Thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients receiving canagliflozin should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Captopril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Carbamazepine: (Moderate) Both thiazide diuretics and carbamazepine are associated with hyponatremia. Coadministration may result in an additive risk of developing hyponatremia. When concurrent therapy with a thiazide diuretic and carbamazepine is necessary, monitor patients for hyponatremia.
    Carbetapentane; Chlorpheniramine; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Carbetapentane; Guaifenesin; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Carbetapentane; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Carbetapentane; Phenylephrine; Pyrilamine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Carbetapentane; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Carbidopa; Levodopa: (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects. (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects.
    Carbidopa; Levodopa; Entacapone: (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects. (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Carbinoxamine; Hydrocodone; Phenylephrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Carbinoxamine; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Carbinoxamine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Cardiac glycosides: (Moderate) Thiazide diuretics can cause hypokalemia, hypomagnesemia, or hypercalcemia which may increase digoxin's pharmacologic effect. Close monitoring of serum digoxin concentrations is essential to avoid enhanced toxicity. It is also recommended that serum potassium, magnesium, and calcium be monitored regularly in patients receiving digoxin.
    Cariprazine: (Moderate) Orthostatic vital signs should be monitored in patients who are at risk for hypotension, such as those receiving cariprazine in combination with antihypertensive agents. Atypical antipsychotics may cause orthostatic hypotension and syncope, most commonly during treatment initiation and dosage increases. Patients should be informed about measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning, or rising slowly from a seated position. Consider a cariprazine dose reduction if hypotension occurs.
    Celecoxib: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Cetirizine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Chlophedianol; Guaifenesin; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Chlordiazepoxide; Clidinium: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Chloroprocaine: (Moderate) Local anesthetics may cause additive hypotension in combination with antihypertensive agents.
    Chlorpheniramine; Codeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Chlorpheniramine; Hydrocodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Chlorpheniramine; Hydrocodone; Phenylephrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Chlorpheniramine; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Chlorpheniramine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Chlorpropamide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Cholestyramine: (Moderate) Cholestyramine, an ion exchange resin, binds hydrochlorothiazide and reduces its absorption from the gastrointestinal tract by up to 85% when co-administered as single doses. Although the manufacturer for Questran recommends that other medicines be taken at least 1 hour before or 4-6 hours after cholestyramine, it has been recommended that thiazides be administered at least 4 hours before or after cholestyramine to minimize the reduction in absorption. By administering hydrochlorothiazide at least 4 hours before cholestyramine, the decrease in absorption of hydrochlorothiazide is approximately 30-35%.
    Cidofovir: (Severe) The administration of cidofovir with another potentially nephrotoxic agent, such as diuretics, is contraindicated. Diuretics should be discontinued at least 7 days prior to beginning cidofovir.
    Cisapride: (Major) Cisapride should be used with great caution in patients receiving thiazide diuretics. Drugs that are associated with depletion of electrolytes may cause cisapride-induced cardiac arrhythmias. Serum electrolytes and creatinine should be assessed prior to administration of cisapride and whenever conditions develop that may affect electrolyte imbalance or renal function.
    Cisatracurium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Citalopram: (Moderate) Citalopram causes dose-dependent QT interval prolongation. Concurrent use of citalopram and medications known to cause electrolyte imbalance may increase the risk of developing QT prolongation. Therefore, caution is advisable during concurrent use of citalopram and diuretics. In addition, patients receiving a diuretic during treatment with citalopram may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH has been reported during therapy with SSRIs. Cases involving serum sodium levels lower than 110 mmol/l have occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of citalopram should be considered in patients who develop symptomatic hyponatremia.
    Clindamycin; Tretinoin: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as thiazide diuretics, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
    Clozapine: (Major) Caution is advisable during concurrent use of clozapine and thiazide diuretics. Clozapine used concomitantly with the antihypertensive agents can increase the risk and severity of hypotension by potentiating the effect of the antihypertensive drug. Treatment with clozapine has been associated with QT prolongation, torsade de pointes (TdP), cardiac arrest, and sudden death. Concurrent use of clozapine and medications known to cause electrolyte imbalance may increase the risk of QT prolongation. (Moderate) Clozapine used concomitantly with the antihypertensive agents can increase the risk and severity of hypotension by potentiating the effect of the antihypertensive drug.
    Cocaine: (Major) Use of cocaine with antihypertensive agents may increase the antihypertensive effects of the antihypertensive medications or may potentiate cocaine-induced sympathetic stimulation.
    Cod Liver Oil: (Major) Dose adjustment of vitamin D or vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D or vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine. (Moderate) Fish oil supplements may cause mild, dose-dependent reductions in systolic or diastolic blood pressure in untreated hypertensive patients. Relatively high doses of fish oil are required to produce any blood pressure lowering effect. Additive reductions in blood pressure may be seen when fish oils are used in a patient already taking antihypertensive agents. (Moderate) High doses of fish oil supplements may produce a blood pressure lowering effect. It is possible that additive reductions in blood pressure may be seen when fish oils are used in a patient already taking antihypertensive agents.
    Codeine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Codeine; Guaifenesin: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Codeine; Phenylephrine; Promethazine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Codeine; Promethazine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Co-Enzyme Q10, Ubiquinone: (Moderate) Co-enzyme Q10, ubiquinone (CoQ10) may lower blood pressure. CoQ10 use in combination with antihypertensive agents may lead to additional reductions in blood pressure in some individuals. Patients who choose to take CoQ10 concurrently with antihypertensive medications should receive periodic blood pressure monitoring. Patients should be advised to inform their prescriber of their use of CoQ10.
    Colestipol: (Moderate) Although to a lesser extent than cholestyramine, colestipol also has been shown to inhibit the GI absorption and therapeutic response of thiazide diuretics. Single doses of colestipol resins reduce the absorption of HCTZ by up to 43%. Administering thiazide diuretics at least 2 hours before colestipol has been suggested to minimize the interaction.
    Conivaptan: (Moderate) There is potential for additive hypotensive effects when conivaptan is coadministered with antihypertensive agents. (Moderate) There is potential for additive hypotensive effects when conivaptan is coadministered with antihypertensive agents.
    Corticosteroids: (Moderate) Additive hypokalemia may occur when non-potassium sparing diuretics, including thiazide diuretics, are coadministered with other drugs with a significant risk of hypokalemia, such as corticosteroids. Monitoring serum potassium levels and cardiac function is advised, and potassium supplementation may be required.
    Cosyntropin: (Moderate) Use cosyntropin cautiously in patients receiving diuretics. Cosyntropin may accentuate the electrolyte loss associated with diuretic therapy.
    Cyclophosphamide: (Moderate) Coadministration of thiazide diuretics and antineoplastic agents such as cyclophosphamide may result in reduced renal excretion of the antineoplastic agent and therefore increased myelosuppressive effects.
    Cyclosporine: (Moderate) Coadministration of cyclosporine and an angiotensin II receptor antagonist, like irbesartan, may increase the risk of hyperkalemia and reduced renal function. In response to cyclosporine-induced renal afferent vasoconstriction and glomerular hypoperfusion, angiotensin II is required to maintain an adequate glomerular filtration rate. Inhibition of angiotensin-converting enzyme (ACE) could reduce renal function acutely. Several cases of acute renal failure have been associated with the addition of enalapril to cyclosporine therapy in renal transplant patients. Also, cyclosporine can cause hyperkalemia, and inhibition of angiotensin II leads to reduced aldosterone concentrations, which can increase the serum potassium concentration. Closely monitor renal function and serum potassium concentrations in patients receiving cyclosporine concurrently with irbesartan.
    Dapagliflozin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Dapagliflozin; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Dapagliflozin; Saxagliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Desloratadine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Desvenlafaxine: (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Dexlansoprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Dexmethylphenidate: (Moderate) Dexmethylphenidate can reduce the hypotensive effect of antihypertensive agents, including angiotensin II receptor antagonists. Periodic evaluation of blood pressure is advisable during concurrent use of dexmethylphenidate and antihypertensive agents, particularly during initial coadministration and after dosage increases of dexmethylphenidate. (Moderate) Dexmethylphenidate can reduce the hypotensive effect of antihypertensive agents, including thiazide diuretics. Periodic evaluation of blood pressure is advisable during concurrent use of dexmethylphenidate and antihypertensive agents, particularly during initial coadministration and after dosage increases of dexmethylphenidate.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Dextromethorphan; Quinidine: (Moderate) Quinidine can decrease blood pressure and should be used cautiously in patients receiving antihypertensive agents due to the potential for additive hypotension.
    Diazoxide: (Moderate) Additive hypotensive effects can occur with the concomitant administration of diazoxide with other antihypertensive agents. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly. The manufacturer advises that IV diazoxide should not be administered to patients within 6 hours of receiving beta-blockers, hydralazine, methyldopa, minoxidil, nitrites, prazosin, reserpine, or other antihypertensive agents. (Moderate) Enhanced hyperglycemia is possible during concurrent use of diazoxide and thiazide diuretics. Additive hypotensive effects can also occur with the concomitant administration of diazoxide with thiazide diuretics.
    Dichlorphenamide: (Moderate) Use dichlorphenamide and diuretics together with caution. Dichlorphenamide increases potassium excretion and can cause hypokalemia and should be used cautiously with other drugs that may cause hypokalemia including loop diuretics and thiazide diuretics. Measure potassium concentrations at baseline and periodically during dichlorphenamide treatment. If hypokalemia occurs or persists, consider reducing the dose or discontinuing dichlorphenamide therapy.
    Diclofenac: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Diclofenac; Misoprostol: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Dicyclomine: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Diethylpropion: (Major) Diethylpropion has vasopressor effects and may limit the benefit of thiazide diuretics. Although leading drug interaction texts differ in the potential for an interaction between diethylpropion and this group of antihypertensive agents, these effects are likely to be clinically significant and have been described in hypertensive patients on these medications. (Moderate) Diethylpropion has vasopressor effects and may limit the benefit of angiotensin II receptor antagonists. Although leading drug interaction texts differ in the potential for an interaction between diethylpropion and this group of antihypertensive agents, these effects are likely to be clinically significant and have been described in hypertensive patients on these medications.
    Diflunisal: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Digitoxin: (Moderate) Thiazide diuretics can cause hypokalemia, hypomagnesemia, or hypercalcemia which may increase digoxin's pharmacologic effect. Close monitoring of serum digoxin concentrations is essential to avoid enhanced toxicity. It is also recommended that serum potassium, magnesium, and calcium be monitored regularly in patients receiving digoxin.
    Digoxin: (Moderate) Caution should be exercised when administering digoxin with drugs that may cause a significant deterioration in renal function including angiotensin II receptor antagonists. A decline in glomerular filtration or tubular secretion may impair the excretion of digoxin. Close monitoring of serum digoxin concentrations is essential to avoid enhanced toxicity. (Moderate) Thiazide diuretics can cause hypokalemia, hypomagnesemia, or hypercalcemia which may increase digoxin's pharmacologic effect. Close monitoring of serum digoxin concentrations is essential to avoid enhanced toxicity. It is also recommended that serum potassium, magnesium, and calcium be monitored regularly in patients receiving digoxin.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Diphenhydramine; Hydrocodone; Phenylephrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Diphenhydramine; Ibuprofen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Diphenhydramine; Naproxen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Diphenhydramine; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Dobutamine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives such as metolazone when administered concomitantly.
    Dofetilide: (Severe) Hypokalemia or hypomagnesemia may occur with administration of potassium-depleting drugs such as loop diuretics and thiazide diuretics, increasing the potential for dofetilide-induced torsade de pointes. Additionally, in patients treated with either hydrochlorothiazide 50 mg or hydrochlorothiazide/triamterene 50 mg/100 mg daily in combination with dofetilide 500 mcg twice daily for 5 days, dofetilide AUC and Cmax concentrations increased by 27% and 21%, respectively, for the hydrochlorothiazide alone group and by 30% and 16%, respectively, for the hydrochlorothiazide/triamterene group. Furthermore, a 197% and 190% QTc increase over time was seen in the hydrochlorothiazide and hydrochlorothiazide/triamterene groups, respectively. Based on these findings, the manufacturer of dofetilide contraindicates the concomitant use of hydrochlorothiazide (alone or in combination with other drugs such as triamterene); these findings can be explained both by an increase in the plasma concentration of dofetilide and a reduction in the serum potassium concentration. In a population pharmacokinetic analysis of plasma dofetilide concentrations, the mean dofetilide clearance of dofetilide was 16% lower in patients on thiazide diuretics. It is prudent to avoid the use of any thiazide diuretic in combination with dofetilide.
    Dolasetron: (Major) The manufacturer warns that the coadministration of dolasetron with diuretics associated with hypokalemia could increase the risk of QT prolongation. Patients taking certain diuretics may develop an electrolyte abnormality that may lead to cardiac dysrhythmias and/or QT prolongation. Hypokalemia or hypomagnesemia may occur with administration of potassium-depleting drugs such as thiazide diuretics, increasing the potential for cardiac arrhythmias. Potassium levels should be within the normal range prior to and during therapy with dolasetron.
    Donepezil; Memantine: (Minor) Memantine reduced the bioavailability of hydrochlorothiazide by roughly 20% in a drug interaction study. The clinical significance of this pharmacokinetic interaction, if any, is unknown.
    Dopamine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives such as metolazone when administered concomitantly.
    Doxacurium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Droperidol: (Moderate) Caution is advised when using droperidol in combination with thiazide diuretics which may lead to electrolyte abnormalities, especially hypokalemia or hypomagnesemia, as such abnormalities may increase the risk for QT prolongation or cardiac arrhythmias.
    Drospirenone; Estradiol: (Moderate) Drospirenone has antimineralocorticoid effects and may increase serum potassium. The concurrent use of angiotensin II receptor antagonists (ARBs) may increase the risk of hyperkalemia, especially in the presence of renal impairment. Monitor serum potassium during the 1st month of drospirenone treatment if ARBs are used concurrently and thereafter as clinically indicated. Also monitor for any changes in blood pressure, fluid retention, or renal function.
    Drospirenone; Ethinyl Estradiol: (Moderate) Drospirenone has antimineralocorticoid effects and may increase serum potassium. The concurrent use of angiotensin II receptor antagonists (ARBs) may increase the risk of hyperkalemia, especially in the presence of renal impairment. Monitor serum potassium during the 1st month of drospirenone treatment if ARBs are used concurrently and thereafter as clinically indicated. Also monitor for any changes in blood pressure, fluid retention, or renal function.
    Drospirenone; Ethinyl Estradiol; Levomefolate: (Moderate) Drospirenone has antimineralocorticoid effects and may increase serum potassium. The concurrent use of angiotensin II receptor antagonists (ARBs) may increase the risk of hyperkalemia, especially in the presence of renal impairment. Monitor serum potassium during the 1st month of drospirenone treatment if ARBs are used concurrently and thereafter as clinically indicated. Also monitor for any changes in blood pressure, fluid retention, or renal function.
    Dulaglutide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Duloxetine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary. (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Empagliflozin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Empagliflozin; Linagliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Empagliflozin; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Enalapril, Enalaprilat: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Enalapril; Felodipine: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Enflurane: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Ephedrine: (Major) The cardiovascular effects of sympathomimetics, such as ephedrine, may reduce the antihypertensive effects produced by thiazide diuretics. Blood pressure and heart rates should be monitored closely to confirm that the desired antihypertensive effect is achieved. (Moderate) The cardiovascular effects of sympathomimetics, such as ephedrine, may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Blood pressure and heart rates should be monitored closely to confirm that the desired antihypertensive effect is achieved.
    Epinephrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives such as metolazone when administered concomitantly.
    Eplerenone: (Major) Monitor serum potassium and serum creatinine concentrations within 3 to 7 days of initiating coadministration of eplerenone and angiotensin II receptor antagonists (ARBs). Hyperkalemia risk is increased when eplerenone is used with ARBs. Patients who develop hyperkalemia may continue eplerenone with proper dose adjustment; eplerenone dose reduction decreases potassium concentrations.
    Epoprostenol: (Moderate) Angiotensin II receptor antagonists can enhance the hypotensive effects of antihypertensive agents if given concomitantly. This additive effect may be desirable, but dosages must be adjusted accordingly.
    Ergocalciferol, Vitamin D2: (Major) Dose adjustment of vitamin D or vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D or vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
    Ertugliflozin; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
    Ertugliflozin; Sitagliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Escitalopram: (Moderate) Patients receiving a diuretic during treatment with escitalopram may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH has been reported during therapy with SSRIs. Cases involving serum sodium levels lower than 110 mmol/l have occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of escitalopram should be considered in patients who develop symptomatic hyponatremia.
    Esomeprazole: (Moderate) Proton pump inhibitors, such as esomeprazole, have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Esomeprazole; Naproxen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy. (Moderate) Proton pump inhibitors, such as esomeprazole, have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Estradiol Cypionate; Medroxyprogesterone: (Minor) Estrogens can induce fluid retention and may increase blood pressure in some patients; patients who are receiving antihypertensive agents concurrently with hormonal contraceptives should be monitored for antihypertensive effectiveness. (Minor) Estrogens can induce fluid retention and may increase blood pressure in some patients; patients who are receiving antihypertensive agents concurrently with hormone therapy should be monitored for antihypertensive effectiveness.
    Estradiol: (Minor) Estrogens can induce fluid retention and may increase blood pressure in some patients; patients who are receiving antihypertensive agents concurrently with hormonal contraceptives should be monitored for antihypertensive effectiveness. (Minor) Estrogens can induce fluid retention and may increase blood pressure in some patients; patients who are receiving antihypertensive agents concurrently with hormone therapy should be monitored for antihypertensive effectiveness.
    Ethanol: (Moderate) Patients should be cautioned that ingesting alcohol can increase the chance of low blood pressure and dizziness when taking a thiazide diuretic or the related drug, metolazone. Patients may wish to limit alcohol ingestion while taking one of these diuretics and should be monitored for signs or symptoms of hypotension, including postural hypotension and dizziness.
    Etodolac: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Etomidate: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Exenatide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Famotidine; Ibuprofen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Fenoprofen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Fentanyl: (Moderate) Fentanyl may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Adjustments to diuretic therapy may be needed in some patients. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Fexofenadine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Fish Oil, Omega-3 Fatty Acids (Dietary Supplements): (Major) Dose adjustment of vitamin D or vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D or vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine. (Moderate) Co-enzyme Q10, ubiquinone (CoQ10) may lower blood pressure. CoQ10 use in combination with antihypertensive agents may lead to additional reductions in blood pressure in some individuals. Patients who choose to take CoQ10 concurrently with antihypertensive medications should receive periodic blood pressure monitoring. Patients should be advised to inform their prescriber of their use of CoQ10. (Moderate) High doses of fish oil supplements may produce a blood pressure lowering effect. It is possible that additive reductions in blood pressure may be seen when fish oils are used in a patient already taking antihypertensive agents.
    Flavoxate: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Fluconazole: (Moderate) Hydrochlorothiazide may decrease the renal clearance of fluconazole. Coadministration of fluconazole 100 mg PO and hydrochlorothiazide 50 mg PO for 10 days in normal volunteers (n=13) resulted in a significant increase in fluconazole AUC and Cmax compared to fluconazole given alone. There was a mean +/- SD increase in fluconazole AUC and Cmax of 45 +/- 31% and 43 +/- 31%, respectively. These changes are attributed to a mean +/- SD reduction in fluconazole renal clearance of 30% +/- 12%.
    Fluocinolone; Hydroquinone; Tretinoin: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as thiazide diuretics, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
    Fluoxetine: (Moderate) Patients receiving a diuretic during treatment with fluoxetine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH has been reported during therapy with SSRIs. Cases involving serum sodium levels lower than 110 mmol/l have occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of fluoxetine should be considered in patients who develop symptomatic hyponatremia.
    Fluoxetine; Olanzapine: (Moderate) Olanzapine may induce orthostatic hypotension and thus enhance the effects of antihypertensive agents. (Moderate) Patients receiving a diuretic during treatment with fluoxetine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH has been reported during therapy with SSRIs. Cases involving serum sodium levels lower than 110 mmol/l have occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of fluoxetine should be considered in patients who develop symptomatic hyponatremia.
    Flurbiprofen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Fluticasone; Salmeterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Fluticasone; Umeclidinium; Vilanterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Fluticasone; Vilanterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Fluvoxamine: (Moderate) Patients receiving a diuretic during treatment with fluvoxamine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH has been reported during therapy with SSRIs. Cases involving serum sodium levels lower than 110 mmol/L have occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of fluvoxamine should be considered in patients who develop symptomatic hyponatremia.
    Formoterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Formoterol; Mometasone: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Fosinopril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Fospropofol: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Gallium Ga 68 Dotatate: (Major) Avoid use of other diuretics with mannitol, if possible. Concomitant administration may potentiate the renal toxicity of mannitol.
    General anesthetics: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Glimepiride: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Glimepiride; Pioglitazone: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Glimepiride; Rosiglitazone: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Glipizide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Glipizide; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Glyburide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Glyburide; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Glycopyrrolate: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Glycopyrrolate; Formoterol: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms. (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Granisetron: (Moderate) According to the manufacturer, caution is warranted when administering granisetron to patients with preexisting electrolyte abnormalities. Patients taking certain diuretics may develop an electrolyte abnormality that may lead to cardiac dysrhythmias and/or QT prolongation. Hypokalemia or hypomagnesemia may occur with administration of potassium-depleting drugs such as loop diuretics and thiazide diuretics, increasing the potential for cardiac arrhythmias.
    Guaifenesin; Hydrocodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Guaifenesin; Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Guaifenesin; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Halofantrine: (Major) Due to the risks of cardiac toxicity of halofantrine in patients with hypokalemia and/or hypomagnesemia, the use of halofantrine should be avoided when feasible in those patients receiving thiazide diuretics. Electrolyte imbalances may occur while on these diuretics, which may in turn predispose patients to the cardiac effects of halofantrine.
    Haloperidol: (Major) In general, antipsychotics like haloperidol should be used cautiously with antihypertensive agents due to the possibility of additive hypotension. The risk of QT prolongation may also be increased during use of haloperidol and medications known to cause electrolyte imbalance such as thiazide diuretics. (Moderate) In general, antipsychotics like haloperidol should be used cautiously with antihypertensive agents due to the possibility of additive hypotension.
    Halothane: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Hawthorn, Crataegus laevigata: (Moderate) Hawthorn, Crataegus laevigata may lower peripheral vascular resistance. Hawthorn use in combination with antihypertensive agents like the angiotensin II receptor antagonists may lead to additional reductions in blood pressure in some individuals. Patients receiving hawthorn concurrently with antihypertensive medications should receive periodic blood pressure monitoring. (Moderate) Hawthorn, Crataegus laevigata may lower peripheral vascular resistance. Hawthorn use in combination with antihypertensive agents may lead to additional reductions in blood pressure in some individuals. Patients receiving hawthorn concurrently with antihypertensive medications should receive periodic blood pressure monitoring.
    Homatropine; Hydrocodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Hydralazine; Isosorbide Dinitrate, ISDN: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary. (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
    Hydrochlorothiazide, HCTZ; Lisinopril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Hydrochlorothiazide, HCTZ; Quinapril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Hydrochlorothiazide, HCTZ; Spironolactone: (Major) Potassium-sparing diuretics, such as spironolactone, should be used with caution in patients taking drugs that may increase serum potassium levels such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients.
    Hydrochlorothiazide, HCTZ; Triamterene: (Major) Potassium-sparing diuretics, such as triamterene, should be used with caution in patients taking drugs that may increase serum potassium levels such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients.
    Hydrocodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Hydrocodone; Ibuprofen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy. (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Hydrocodone; Phenylephrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Hydrocodone; Potassium Guaiacolsulfonate: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Hydrocodone; Pseudoephedrine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Hydromorphone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Hyoscyamine: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Major) Thiazide diuretics may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Ibuprofen lysine: (Moderate) Ibuprofen lysine may reduce the effect of diuretics; diuretics can increase the risk of nephrotoxicity of NSAIDs in dehydrated patients. During coadministration of NSAIDs and diuretic therapy, patients should be monitored for changes in the effectiveness of their diuretic therapy and for signs and symptoms of renal impairment.
    Ibuprofen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Ibuprofen; Oxycodone: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy. (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Ibuprofen; Pseudoephedrine: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Icosapent ethyl: (Moderate) Thiazide diuretics may exacerbate hypertriglyceridemia and should be discontinued or changed to alternate therapy, if possible, prior to initiation of icosapent ethyl.
    Iloperidone: (Moderate) Secondary to alpha-blockade, iloperidone can produce vasodilation that may result in additive effects during concurrent use with antihypertensive agents. The potential reduction in blood pressure can precipitate orthostatic hypotension and associated dizziness, tachycardia, and syncope. If concurrent use of iloperidone and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position. Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known.
    Iloprost: (Moderate) Angiotensin II receptor antagonists can enhance the hypotensive effects of antihypertensive agents if given concomitantly. This additive effect may be desirable, but dosages must be adjusted accordingly.
    Inamrinone: (Moderate) Hypokalemia may occur due to excessive diuresis during inamrinone therapy. Fluid and electrolyte changes and renal function should be carefully monitored during inamrinone therapy.
    Incretin Mimetics: (Moderate) Angiotensin II receptor antagonists may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving these drugs concomitantly should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Indacaterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Indacaterol; Glycopyrrolate: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms. (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Indapamide: (Moderate) The effects of indapamide may be additive when administered with other antihypertensive agents or diuretics. In some patients, this may be desirable, but orthostatic hypotension may occur. Angiotensin II receptor antagonists tend to reverse the potassium loss, but not the serum uric acid rise associated with thiazide diuretic monotherapy.
    Indomethacin: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Inotersen: (Moderate) Use caution with concomitant use of inotersen and diuretics due to the risk of glomerulonephritis and nephrotoxicity.
    Insulin Degludec; Liraglutide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Insulin Glargine; Lixisenatide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Insulins: (Moderate) Monitor patients receiving angiotensin II receptor antagonists concomitantly with insulin for changes in glycemic control. Angiotensin II receptor antagonists may enhance the hypoglycemic effects of insulin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. (Moderate) Monitor patients receiving insulin closely for changes in diabetic control when thiazide diuretics are instituted or discontinued; dosage adjustments may be required. Thiazide diuretics can decrease the hypoglycemic effects of insulin by producing an increase in blood glucose levels. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes.
    Intravenous Lipid Emulsions: (Moderate) High doses of fish oil supplements may produce a blood pressure lowering effect. It is possible that additive reductions in blood pressure may be seen when fish oils are used in a patient already taking antihypertensive agents.
    Isocarboxazid: (Moderate) Additive hypotensive effects may be seen when isocarboxazid is combined with angiotensin II receptor antagonists. Careful monitoring of blood pressure is suggested during concurrent therapy of isocarboxazid with angiotensin II receptor antagonists. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider during concurrent use of isocarboxazid and an angiotensin II receptor antagonist. (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives. Careful monitoring of blood pressure is suggested during concurrent therapy of MAOIs with diuretics. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider.
    Isoflurane: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Isoproterenol: (Moderate) The pharmacologic effects of isoproterenol may cause an increase in blood pressure. If isoproterenol is used concomitantly with antihypertensives, the blood pressure should be monitored as the administration of isoproterenol can compromise the effectiveness of antihypertensive agents.
    Isosorbide Dinitrate, ISDN: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary. (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
    Isosorbide Mononitrate: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary. (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
    Ketamine: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Ketoprofen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Ketorolac: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Lansoprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Lansoprazole; Naproxen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy. (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Lesinurad; Allopurinol: (Moderate) The occurrence of certain hypersensitivity reactions may be increased in patients with renal impairment who receive allopurinol and thiazide diuretics in combination. The precise mechanism for such events is unclear but likely immune-mediated and may be related to an effect of oxypurinol; elevated oxypurinol concentrations appear to be associated with hypersensitivity reactions; decreased clearance of this metabolite may occur with renal impairment and with the concurrent use of thiazide diuretics. Severe skin reactions include exfoliative dermatitis, toxic epidermal necrolysis and Steven's Johnson syndrome; some reactions have been fatal. In addition, thiazide diuretics, like hydrochlorothiazide, can cause hyperuricemia. Since thiazides reduce the clearance of uric acid, patients with gout or hyperuricemia may have exacerbations of their disease.
    Levalbuterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Levodopa: (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects. (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects.
    Levomethadyl: (Moderate) Caution is advised when using levomethadyl in combination with other agents that may lead to electrolyte abnormalities, especially hypokalemia or hypomagnesemia. Agents that require monitoring for potential hypokalemia include thiazide diuretics.
    Levomilnacipran: (Moderate) Levomilnacipran has been associated with an increase in blood pressure. The effectiveness of angiotensin II receptor antagonists may be diminished during concurrent use of levomilnacipran. It is advisable to monitor blood pressure if the combination is necessary. (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Linagliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Linagliptin; Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Liraglutide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Lisdexamfetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed. (Moderate) Thiazides may increase blood levels and therefore potentiate the actions of amphetamines. Thiazide diuretics may increase urinary pH, acting as a urinary alkalinizer, thus reducing urinary excretion and increasing blood concentrations of the amphetamine. Co-administration of amphetamines and urinary alkalinizing agents should be avoided if possible. If needed, monitor for common amphetamine side effects, including decreased appetite, anxiety, dizziness, dry mouth, irritability, insomnia, nausea, increased blood pressure or increased heart rate. Amphetamines increase both systolic and diastolic blood pressure. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
    Lisinopril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Lithium: (Major) Angiotensin II receptor antagonists (ARBs) should be used very cautiously, if at all, in patients already receiving lithium. The risk of lithium toxicity is increased in patients receiving medications that may affect kidney function, such ARBs. These drugs decrease lithium clearance, possibly as a result of sodium depletion which leads to increased renal tubular reabsorption of lithium. If combination therapy cannot be avoided, begin with lower doses of lithium and be alert for evidence of lithium toxicity (e.g., nausea, vomiting, anorexia, drowsiness, dysarthria, tremor, confusion, lethargy, ECG changes, etc.). Consider reducing the lithium dosage in previously established patients and monitor lithium concentrations and patient response and tolerability. Conversely, clinicians should be alert to the possibility of loss of lithium effectiveness if ARBs are discontinued in a patient stabilized on lithium. According to the Beers Criteria, concurrent use of lithium and ACE inhibitors may result in a clinically important drug interaction particularly in older adults; the panel recommends avoiding concurrent use due to an increased risk of lithium toxicity. If the combination is medically necessary, monitoring of lithium concentrations is recommended. (Major) Concurrent use of lithium and thiazide diuretics may result in lithium toxicity. Therapeutic doses of thiazide diuretics can result in an approximate 25% to 40% decrease in lithium clearance, potentially leading to significant toxicity. Lithium is primarily re-absorbed from the proximal tubules, and thiazide diuretics block sodium reabsorption at the distal tubule, which results in sodium depletion and subsequent compensatory reabsorption of sodium and lithium at the proximal tubules. If treatment with lithium and a thiazide diuretic cannot be avoided, patients should have their serum lithium concentrations closely monitored, and the lithium dosage adjusted if necessary. Monitoring for changes in lithium effectiveness as well as careful assessment of lithium concentrations is advisable, particularly during initial co-administration and after dose changes or discontinuation of the diuretic. In some cases, thiazide diuretics may be used to counteract lithium-induced polyuria, although close monitoring is necessary if such treatment is initiated. There is a lack of evidence to evaluate the safety of lithium and metolazone, a thiazide-like diuretic. The manufacturer of metolazone recommends general avoidance of diuretics and lithium due to the potential for lithium toxicity.
    Lixisenatide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Loop diuretics: (Moderate) Coadministration of furosemide and Angiotensin-converting enzyme inhibitors (ACE inhibitors) or angiotensin II receptor antagonists may result in severe hypotension and deterioration in renal function, including renal failure. Hyponatremia or hypovolemia predisposes patients to acute hypotensive episodes following initiation of ACE inhibitor therapy. While ACE inhibitors and loop diuretics are routinely administered together in the treatment of heart failure, if an ACE inhibitor is to be administered to a patient receiving furosemide, initial doses should be conservative. (Moderate) Concomitant use of a thiazide diuretiic, or the related drug metolazone, with a loop diuretic can cause additive electrolyte and fluid loss. In patients with creatinine clearances > 30 ml/min, the combinations may also lead to profound fluid and electrolyte loss in some patients. Thus, use cautiously and with monitoring of renal function, blood pressure, cardiac status, electrolytes (especially potassium), and monitor the clinical response for the condition treated.
    Loratadine; Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Lovastatin; Niacin: (Moderate) Cutaneous vasodilation induced by niacin may become problematic if high-dose niacin is used concomitantly with other antihypertensive agents. This effect is of particular concern in the setting of acute myocardial infarction, unstable angina, or other acute hemodynamic compromise.
    Lurasidone: (Moderate) Due to the antagonism of lurasidone at alpha-1 adrenergic receptors, the drug may enhance the hypotensive effects of alpha-blockers and other antihypertensive agents. If concurrent use of lurasidone and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position. Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known.
    Magnesium Salts: (Moderate) Diuretics may interfere with the kidneys ability to regulate magnesium concentrations. Long-term use of thiazide diuretics may impair the magnesium-conserving ability of the kidneys and lead to hypomagnesemia. In addition, use caution when prescribing sulfate salt bowel preps in patients taking medications that may affect renal function such as diuretics.
    Magnesium Sulfate; Potassium Sulfate; Sodium Sulfate: (Moderate) Use caution when prescribing sulfate salt bowel preparation in patients taking concomitant medications that may affect renal function such as angiotensin II receptor antagonists. (Moderate) Use caution when prescribing sulfate salt bowel preparation in patients taking concomitant medications that may affect renal function such as diuretics.
    Mannitol: (Major) Avoid use of other diuretics with mannitol, if possible. Concomitant administration may potentiate the renal toxicity of mannitol.
    Meclofenamate Sodium: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Mefenamic Acid: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Meglitinides: (Moderate) Angiotensin II receptor antagonists (ARB) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Meloxicam: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Memantine: (Minor) Memantine reduced the bioavailability of hydrochlorothiazide by roughly 20% in a drug interaction study. The clinical significance of this pharmacokinetic interaction, if any, is unknown.
    Mepenzolate: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Meperidine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Meperidine; Promethazine: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Mequinol; Tretinoin: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as thiazide diuretics, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
    Mestranol; Norethindrone: (Minor) Estrogen containing oral contraceptives can induce fluid retention and may increase blood pressure in some patients; monitor patients receiving concurrent therapy to confirm that the desired antihypertensive effect is being obtained.
    Metaproterenol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Metformin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients.
    Metformin; Pioglitazone: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Metformin; Repaglinide: (Moderate) Angiotensin II receptor antagonists (ARB) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Metformin; Rosiglitazone: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Metformin; Saxagliptin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Metformin; Sitagliptin: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of metformin by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. ARBs may rarely reduce renal function, a risk factor for reduced renal clearance of metformin. Patients receiving these drugs together should be monitored for changes in renal function and glycemic control. (Moderate) Certain drugs, such as thiazide diuretics, tend to produce hyperglycemia and may lead to loss of glycemic control. The effects of thiazide diuretics on glycemic control appear to be dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, thiazide diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. Patients receiving metformin should be monitored for changes in blood glucose control if any of these diuretics are added or deleted. Dosage adjustments may be necessary in some patients. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Methadone: (Moderate) Diuretics can cause electrolyte disturbances such as hypomagnesemia and hypokalemia, which may prolong the QT interval. As methadone may also prolong the QT interval, cautious coadministration with diuretics is needed. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Methamphetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents, such as angiotensin II receptor antagonists. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed. (Moderate) Thiazides may increase blood levels and therefore potentiate the actions of amphetamines. Thiazide diuretics may increase urinary pH, acting as a urinary alkalinizer, thus reducing urinary excretion and increasing blood concentrations of the amphetamine. Co-administration of amphetamines and urinary alkalinizing agents should be avoided if possible. If needed, monitor for common amphetamine side effects, including decreased appetite, anxiety, dizziness, dry mouth, irritability, insomnia, nausea, increased blood pressure or increased heart rate. Amphetamines increase both systolic and diastolic blood pressure. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
    Methazolamide: (Moderate) Thiazide diuretics may increase the risk of hypokalemia if used concurrently with methazolamide. Monitor serum potassium levels to determine the need for potassium supplementation and/or alteration in drug therapy. There may also be an additive diuretic or hyperuricemic effect.
    Methenamine: (Major) Thiazide diuretics may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde.
    Methenamine; Sodium Acid Phosphate: (Major) Thiazide diuretics may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Major) Thiazide diuretics may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Methohexital: (Moderate) Concurrent use of methohexital and antihypertensive agents increases the risk of developing hypotension.
    Methotrexate: (Moderate) Coadministration of thiazide diuretics and antineoplastic agents such as methotrexate may result in reduced renal excretion of the antineoplastic agent and therefore increased myelosuppressive effects.
    Methoxsalen: (Moderate) Concomitant administration of methoxsalen and other photosensitizing agents, such as thiazide diuretics, can increase the incidence or severity of photsensitization from either compound.
    Methscopolamine: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Methylphenidate: (Moderate) Methylphenidate can reduce the hypotensive effect of antihypertensive agents such as angiotensin II receptor antagonists. Periodic evaluation of blood pressure is advisable during concurrent use of methylphenidate and antihypertensive agents, particularly during initial coadministration and after dosage increases of methylphenidate. (Moderate) Methylphenidate can reduce the hypotensive effect of antihypertensive agents such as thiazide diuretics. Periodic evaluation of blood pressure is advisable during concurrent use of methylphenidate and antihypertensive agents, particularly during initial coadministration and after dosage increases of methylphenidate.
    Metoclopramide: (Minor) Coadministration of thiazides and prokinetic agents may result in decreased bioavailability of the thiazide diuretic.
    Midodrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly.
    Miglitol: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Milnacipran: (Moderate) Milnacipran has been associated with an increase in blood pressure. The effectiveness of antihypertensive agents may be diminished during concurrent use of milnacipran. It is advisable to monitor blood pressure if the combination is necessary. (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Milrinone: (Moderate) Concurrent administration of antihypertensive agents could lead to additive hypotension when administered with milrinone. Titrate milrinone dosage according to hemodynamic response.
    Mirtazapine: (Moderate) Hyponatremia has been reported very rarely during mirtazapine administration. Caution is advisable in patients receiving medications known to cause hyponatremia, such as diuretics. Hyponatremia may manifest as headache, difficulty concentrating, memory impairment, confusion, weakness, and unsteadiness which may result in falls. Severe manifestations include hallucinations, syncope, seizure, coma, respiratory arrest, and death. Symptomatic hyponatremia may require discontinuation of mirtazapine, as well as implementation of the appropriate medical interventions.
    Mivacurium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Moexipril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Morphine: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Morphine; Naltrexone: (Moderate) Morphine may reduce the efficacy of diuretics due to induction of the release of antidiuretic hormone. Morphine may also cause acute urinary retention by causing a spasm of the bladder sphincter; men with enlarged prostates may have a higher risk of this reaction. In addition, opiate agonists may potentiate orthostatic hypotension when used concurrently with diuretics.
    Nabumetone: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Naproxen: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Naproxen; Pseudoephedrine: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Naproxen; Sumatriptan: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Nateglinide: (Moderate) Angiotensin II receptor antagonists (ARB) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Nefazodone: (Minor) Although relatively infrequent, nefazodone may cause orthostatic hypotension in some patients; this effect may be additive with antihypertensive agents. Blood pressure monitoring and dosage adjustments of either drug may be necessary. (Minor) Although relatively infrequent, nefazodone may cause orthostatic hypotension in some patients; this effect may be additive with antihypertensive agents. Blood pressure monitoring is recommended. Dependent upon clinical response, dosage adjustments of either drug may be necessary.
    Nesiritide, BNP: (Major) The potential for hypotension may be increased when coadministering nesiritide with antihypertensive agents. (Moderate) The potential for hypotension may be increased when coadministering nesiritide with antihypertensive agents.
    Neuromuscular blockers: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Niacin, Niacinamide: (Moderate) Cutaneous vasodilation induced by niacin may become problematic if high-dose niacin is used concomitantly with other antihypertensive agents. This effect is of particular concern in the setting of acute myocardial infarction, unstable angina, or other acute hemodynamic compromise.
    Niacin; Simvastatin: (Moderate) Cutaneous vasodilation induced by niacin may become problematic if high-dose niacin is used concomitantly with other antihypertensive agents. This effect is of particular concern in the setting of acute myocardial infarction, unstable angina, or other acute hemodynamic compromise.
    Nitrates: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary. (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
    Nitroglycerin: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary. (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
    Nitroprusside: (Moderate) Additive hypotensive effects may occur when nitroprusside is used concomitantly with other antihypertensive agents. Dosages should be adjusted carefully, according to blood pressure. (Moderate) Additive hypotensive effects may occur when nitroprusside is used concomitantly with other antihypertensive agents. Dosages should be adjusted carefully, according to blood pressure.
    Nonsteroidal antiinflammatory drugs: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy. (Moderate) Nonsteroidal antiinflammatory drugs (NSAIDs) (including selective COX-2 inhibitors) may alter the response to Angiotensin II receptor blockers due to inhibition of vasodilatory prostaglandins. Among NSAIDs, indomethacin, naproxen, and piroxicam may have the greatest pressor effect, while the effects of sulindac and nabumetone may be significantly less. In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function who are being treated with NSAIDs, coadministration of angiotensin II receptor antagonists may result in further deterioration of renal function, including acute renal failure. These effects are usually reversible.
    Norepinephrine: (Moderate) Thiazide diuretics can cause decreased arterial responsiveness to norepinephrine, but the effect is not sufficient to preclude their coadministration.
    Octreotide: (Moderate) Patients receiving diuretics or other agents to control fluid and electrolyte balance may require dosage adjustments while receiving octreotide due to additive effects.
    Olanzapine: (Moderate) Olanzapine may induce orthostatic hypotension and thus enhance the effects of antihypertensive agents.
    Olodaterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Omeprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Omeprazole; Sodium Bicarbonate: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Ondansetron: (Moderate) The coadministration of ondansetron with diuretics associated with hypokalemia could increase the risk of QT prolongation. Potassium levels should be within the normal range prior to and during therapy with ondansetron.
    Oprelvekin, rh-IL-11: (Major) Patients receiving thiazide diuretics during oprelvekin, rh-IL-11 therapy are at increased risk for developing severe hypokalemia; close monitoring of fluid and electrolyte status is warranted during concurrent diuretic and oprelvekin therapy.
    Oxaprozin: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Oxybutynin: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Oxycodone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Oxymetazoline: (Major) The vasoconstricting actions of oxymetazoline, an alpha adrenergic agonist, may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. If these drugs are used together, closely monitor for changes in blood pressure. (Major) The vasoconstricting actions of oxymetazoline, an alpha adrenergic agonist, may reduce the antihypertensive effects produced by diuretics. If these drugs are used together, closely monitor for changes in blood pressure.
    Oxymorphone: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Paliperidone: (Moderate) Paliperidone may cause orthostatic hypotension, thereby enhancing the hypotensive effects of antihypertensive agents. Orthostatic vital signs should be monitored in patients receiving paliperidone and angiotensin II receptor antagonists who are susceptible to hypotension. (Moderate) Paliperidone may cause orthostatic hypotension, thereby enhancing the hypotensive effects of antihypertensive agents. Orthostatic vital signs should be monitored in patients receiving paliperidone and thiazide diuretics who are susceptible to hypotension.
    Pancuronium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Pantoprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Paroxetine: (Moderate) Patients receiving a diuretic during treatment with paroxetine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH has been reported during therapy with SSRIs. Cases involving serum sodium levels lower than 110 mmol/l have occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of paroxetine should be considered in patients who develop symptomatic hyponatremia.
    Pasireotide: (Major) Cautious use of pasireotide and medicines that can affect potassium or magnesium concentrations such as diuretics is advised. Pasireotide may prolong the QT interval, and hypokalemia and/or hypomagnesemia are risk factors for QT prolongation. Assess the patient's potassium and magnesium concentration before and periodically during pasireotide receipt. Correct hypokalemia and hypomagnesemia before pasireotide receipt.
    Pentamidine: (Moderate) Drugs that are associated with hypokalemia and/or hypomagnesemia such as thiazide diuretics should be used with caution in patients also receiving pentamidine. Since pentamidine may cause QT prolongation independently of electrolyte imbalances, the risk for cardiac arrhythmias is potentiated by the concomitant use of agents associated with electrolyte loss. Closely monitor serum electrolytes during pentamidine therapy.
    Pentoxifylline: (Moderate) Pentoxifylline has been used concurrently with antihypertensive drugs (beta blockers, diuretics) without observed problems. Small decreases in blood pressure have been observed in some patients treated with pentoxifylline; periodic systemic blood pressure monitoring is recommended for patients receiving concomitant antihypertensives. If indicated, dosage of the antihypertensive agents should be reduced.
    Perindopril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Perindopril; Amlodipine: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Phendimetrazine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly.
    Phenelzine: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives. Careful monitoring of blood pressure is suggested during concurrent therapy of MAOIs with diuretics. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider. (Moderate) Additive hypotensive effects may be seen when phenelzine is combined with angiotensin II receptor antagonists. Careful monitoring of blood pressure is suggested during concurrent therapy of phenelzine with angiotensin II receptor antagonists. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider during concurrent use of phenelzine and angiotensin II receptor antagonists.
    Phenothiazines: (Moderate) Electrolyte disturbances (e.g., hypokalemia, hypomagnesemia, hypercalcemia) may occur with administration of thiazide diuretics, and electrolyte disturbances may increase the potential for proarrhythmic effects (e.g., QT prolongation, torsade de pointes), particularly with mesoridazine, thioridazine, or chlorpromazine. In the absence of electrolyte imbalances, these agents can be used together safely with appropriate monitoring; clinicians should monitor for evidence of electrolyte disturbances or cardiac-related patient complaints. Thiazide diuretics may potentiate the orthostatic hypotension that can be seen with the use of the phenothiazine antipsychotics.
    Phentermine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly.
    Phentermine; Topiramate: (Major) Concurrent use or topiramate, a carbonic anhydrase inhibitor, with non-potassium sparing diuretics (e.g., thiazide diuretics) may potentiate the potassium-wasting action of these diuretics. Additionally, the addition of HCTZ to topiramate therapy may require a reduction in the topiramate dose. Alternatively, the discontinuation of HCTZ therapy may require a dose increase in topiramate. In a pharmacokinetic drug interaction study, the topiramate Cmax and AUC increased by 27% and 29% when HCTZ was added to topiramate. The clinical significance of this change is unknown. The steady-state pharmacokinetics of HCTZ were not altered to any significant degree. (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly.
    Phenylephrine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Phenylephrine; Promethazine: (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Well-controlled hypertensive patients receiving phenylephrine at recommended doses do not appear at high risk for significant elevations in blood pressure; however, increased blood pressure (especially systolic hypertension) has been reported in some patients. (Moderate) The cardiovascular effects of sympathomimetics may reduce the antihypertensive effects produced by diuretics. Well-controlled hypertensive patients receiving decongestant sympathomimetics at recommended doses do not appear at high risk for significant elevations in blood pressure, however, increased blood pressure has been reported in some patients.
    Photosensitizing agents: (Moderate) Thiazide diuretics may cause photosensitivity and may increase the photosensitization effects of photosensitizing agents used in photodynamic therapy. Prevention of photosensitivity includes adequate protection from sources of UV radiation (e.g., avoiding sun exposure and tanning booths) and the use of protective clothing and sunscreens on exposed skin.
    Pimozide: (Major) Pimozide is associated with a well-established risk of QT prolongation and torsade de pointes (TdP). Use of pimozide and medications known to cause electrolyte imbalance may increase the risk of QT prolongation. Therefore, caution is advisable during concurrent use of pimozide and thiazide diuretics. According to the manufacturer, potassium deficiencies should be correctly prior to treatment with pimozide and normalized potassium levels should be maintained during treatment.
    Pioglitazone: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Pirbuterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Piroxicam: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Polycarbophil: (Moderate) Coadministration may lead to hypercalcemia because thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Each 625 mg of calcium polycarbophil contains a substantial amount of calcium (approximately 125 mg). Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium polycarbophil is used concomitantly, monitoring of serum calcium may be prudent.
    Polyethylene Glycol; Electrolytes: (Moderate) Use caution when prescribing sulfate salt bowel preparation in patients taking concomitant medications that may affect renal function such as angiotensin II receptor antagonists. (Moderate) Use caution when prescribing sulfate salt bowel preparation in patients taking concomitant medications that may affect renal function such as diuretics.
    Polyethylene Glycol; Electrolytes; Ascorbic Acid: (Moderate) Use caution when prescribing sulfate salt bowel preparation in patients taking concomitant medications that may affect renal function such as angiotensin II receptor antagonists. (Moderate) Use caution when prescribing sulfate salt bowel preparation in patients taking concomitant medications that may affect renal function such as diuretics.
    Porfimer: (Moderate) Thiazide diuretics may cause photosensitivity and may increase the photosensitization effects of photosensitizing agents used in photodynamic therapy. Prevention of photosensitivity includes adequate protection from sources of UV radiation (e.g., avoiding sun exposure and tanning booths) and the use of protective clothing and sunscreens on exposed skin.
    Potassium: (Major) Potassium salts should be used with caution in patients taking drugs that may increase serum potassium levels such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients. Also, use caution when prescribing sulfate salt bowel preparation in patients taking concomitant medications that may affect renal function such as angiotensin II receptor antagonists.
    Pramlintide: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of pramlintide by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with pramlintide should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Prazosin: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
    Prilocaine; Epinephrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives such as metolazone when administered concomitantly.
    Probenecid: (Moderate) Thiazide diuretics can cause hyperuricemia. Although this effect represents a pharmacodynamic interaction and not a pharmacokinetic one, dosage adjustments of probenecid may be necessary if these agents are administered concurrently to patients being treated with probenecid.
    Procainamide: (Moderate) Procainamide can decrease blood pressure and should be used cautiously in patients receiving antihypertensive agents. Intravenous administration of procainamide is more likely to cause hypotensive effects. (Moderate) Procainamide can decrease blood pressure and should be used cautiously in patients receiving antihypertensive agents. Intravenous administration of procainamide is more likely to cause hypotensive effects.
    Procaine: (Moderate) Local anesthetics may cause additive hypotension in combination with antihypertensive agents. (Moderate) Local anesthetics may cause additive hypotension in combination with antihypertensive agents.
    Propantheline: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Propofol: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    Pseudoephedrine: (Moderate) Sympathomimetics can antagonize the effects of antihypertensives when administered concomitantly. (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by angiotensin II receptor antagonists. Monitor heart rate and blood pressure.
    Quinapril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Quinidine: (Moderate) Quinidine can decrease blood pressure and should be used cautiously in patients receiving antihypertensive agents due to the potential for additive hypotension.
    Rabeprazole: (Moderate) Proton pump inhibitors have been associated with hypomagnesemia. Hypomagnesemia occurs with thiazide diuretics (chlorothiazide, hydrochlorothiazide, indapamide, and metolazone). Low serum magnesium may lead to serious adverse events such as muscle spasm, seizures, and arrhythmias. Therefore, clinicians should monitor serum magnesium concentrations periodically in patients taking a PPI and diuretics concomitantly. Patients who develop hypomagnesemia may require PPI discontinuation in addition to magnesium replacement.
    Ramipril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Rapacuronium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Rasagiline: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives. Careful monitoring of blood pressure is suggested during concurrent therapy of MAOIs with diuretics. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider. (Moderate) Additive hypotensive effects may be seen when rasagiline is combined with angiotensin II receptor antagonists. Careful monitoring of blood pressure is suggested during coadministration. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider.
    Remifentanil: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Repaglinide: (Moderate) Angiotensin II receptor antagonists (ARB) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Risperidone: (Moderate) Risperidone may induce orthostatic hypotension and thus enhance the hypotensive effects of angiotensin II receptor antagonists. Lower initial doses or slower dose titration of risperidone may be necessary in patients receiving angiotensin II receptor antagonists concomitantly. (Moderate) Risperidone may induce orthostatic hypotension and thus enhance the hypotensive effects of antihypertensive agents. Lower initial doses or slower dose titration of risperidone may be necessary in patients receiving antihypertensive agents concomitantly.
    Rocuronium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Rofecoxib: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Rosiglitazone: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Salicylates: (Moderate) Salicylates can increase the risk of renal toxicity in patients receiving diuretics. Salicylates inhibit renal prostaglandin synthesis, which can lead to fluid retention and increased peripheral vascular resistance. Salicylates may decrease the hyperuricemic effect of hydrochlorothiazide.
    Salmeterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Saxagliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Scopolamine: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Selegiline: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives. Careful monitoring of blood pressure is suggested during concurrent therapy of MAOIs with diuretics. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider. (Moderate) Additive hypotensive effects may be seen when selegiline is combined with angiotensin II receptor antagonists. Careful monitoring of blood pressure is suggested during coadministration. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider.
    Semaglutide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Serotonin norepinephrine reuptake inhibitors: (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Sertraline: (Moderate) Patients receiving a diuretic during treatment with sertraline may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH has been reported during therapy with SSRIs. Cases involving serum sodium levels lower than 110 mmol/l have occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of sertraline should be considered in patients who develop symptomatic hyponatremia.
    Sevoflurane: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
    SGLT2 Inhibitors: (Moderate) Patients receiving these drugs concomitantly should be monitored for changes in blood pressure, volume status, renal function, serum potassium and other electrolytes, and for glycemic control. When an SGLT2 inhibitor is initiated, mild diuresis and naturesis occurs, producing intravascular volume contraction. These effects may be additive to certain antihypertensive medications, such as the angiotensin II receptor antagonists (also known as angiotensin receptor blockers or ARBs). Patients with impaired renal function (eGFR less than 60 mL/minute/1.73 m2), low systolic blood pressure, or who are elderly may also be at a greater risk. Volume status should be assessed and corrected. In addition, some SGLT2 inhibitors, like canagliflozin, can increase serum potassium. Monitor serum potassium levels periodically and monitor for hyperkalemia. ARBs may also enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity.
    Silodosin: (Moderate) During clinical trials with silodosin, the incidence of dizziness and orthostatic hypotension was higher in patients receiving concomitant antihypertensive treatment. Thus, caution is advisable when silodosin is administered with antihypertensive agents. (Moderate) During clinical trials with silodosin, the incidence of dizziness and orthostatic hypotension was higher in patients receiving concomitant antihypertensive treatment. Thus, caution is advisable when silodosin is administered with antihypertensive agents.
    Simvastatin; Sitagliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Sitagliptin: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary. Finally, both thiazides and sulfonylureas have been reported to cause photosensitivity reactions; concomitant use may increase the risk of photosensitivity.
    Sodium Phosphate Monobasic Monohydrate; Sodium Phosphate Dibasic Anhydrous: (Moderate) Concomitant use of medicines with potential to alter renal perfusion or function such as angiotensin II receptor antagonists, may increase the risk of acute phosphate nephropathy in patients taking sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous. (Moderate) Concomitant use of medicines with potential to alter renal perfusion or function such as diuretics, may increase the risk of acute phosphate nephropathy in patients taking sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous.
    Sodium picosulfate; Magnesium oxide; Anhydrous citric acid: (Moderate) Use caution when prescribing sodium picosulfate; magnesium oxide; anhydrous citric acid in patients taking concomitant medications that may affect renal function such as angiotensin II receptor antagonists. In addition, use caution in patients receiving drugs where hypokalemia is a particular risk. (Moderate) Use caution when prescribing sodium picosulfate; magnesium oxide; anhydrous citric acid in patients taking concomitant medications that may affect renal function such as diuretics. In addition, use caution in patients receiving drugs where hypokalemia is a particular risk.
    Solifenacin: (Minor) Diuretics can increase urinary frequency, which may aggravate bladder symptoms. Risk versus benefit should be addressed in patients receiving diuretics and solifenacin.
    Spironolactone: (Major) Potassium-sparing diuretics, such as spironolactone, should be used with caution in patients taking drugs that may increase serum potassium levels such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients.
    Streptozocin: (Minor) Because streptozocin is nephrotoxic, concurrent or subsequent administration of other nephrotoxic agents (e.g,. aminoglycosides, amphotericin B, cisplatin, foscarnet, or diuretics) could exacerbate the renal insult.
    Succinylcholine: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Sufentanil: (Moderate) Opiate agonists may potentiate orthostatic hypotension when used concurrently with thiazide diuretics.
    Sulfacetamide: (Moderate) Sulfonamides may cause photosensitization and may increase the photosensitizing effects of thiazide diuretics.
    Sulfacetamide; Sulfur: (Moderate) Sulfonamides may cause photosensitization and may increase the photosensitizing effects of thiazide diuretics.
    Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Major) Avoid the concomitant use of sulfamethoxazole; trimethoprim and thiazide diuretics. An increased incidence of thrombocytopenia with purpura has been reported in elderly patients during coadministration. (Moderate) Monitor for hyperkalemia if concomitant use of an angiotensin II receptor antagonist and trimethoprim is necessary. Hyperkalemia may be more significant in patients receiving IV trimethoprim. For those patients at higher risk of hyperkalemia (e.g., the elderly, patients with underlying disorders of potassium metabolism, and those with renal dysfunction), consideration of an alternate antibiotic may be warranted. Trimethoprim has a potassium-sparing effect on the distal nephron and may induce hyperkalemia, especially in those with pre-existing risk factors.
    Sulfinpyrazone: (Moderate) Sulfinpyrazone facilitates urinary excretion of uric acid and thereby decreases plasma urate concentrations. Thiazide diuretics can cause hyperuricemia. Dosage adjustments of sulfinpyrazone may be necessary if thiazides are administered concurrently.
    Sulfonylureas: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Sulindac: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Tazarotene: (Moderate) The manufacturer states that tazarotene should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as thiazide diuretics, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
    Tegaserod: (Minor) Coadminisitration of thiazides and prokinetic agents may result in decreased bioavailability of the thiazide diuretic.
    Terbutaline: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Tetrabenazine: (Moderate) Tetrabenazine may induce orthostatic hypotension and thus enhance the hypotensive effects of antihypertensive agents. Lower initial doses or slower dose titration of tetrabenazine may be necessary in patients receiving antihypertensive agents concomitantly.
    Tetracaine: (Moderate) Local anesthetics may cause additive hypotension in combination with antihypertensive agents. Use extreme caution with the concomitant use of tetracaine and antihypertensive agents.
    Thiazolidinediones: (Moderate) Angiotensin II receptor antagonists (ARBs) may enhance the hypoglycemic effects of antidiabetic agents by improving insulin sensitivity. In addition, angiotensin II receptor antagonists have been associated with a reduced incidence in the development of new-onset diabetes in patients with hypertension or other cardiac disease. Patients receiving an ARB in combination with antidiabetic agents should be monitored for changes in glycemic control. (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Thiopental: (Moderate) Concurrent use of thiopental and alpha-blockers or antihypertensive agents increases the risk of developing hypotension.
    Thiothixene: (Moderate) Thiothixene should be used cautiously in patients receiving antihypertensive agents. Additive hypotensive effects are possible.
    Tiotropium; Olodaterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Tizanidine: (Moderate) Concurrent use of tizanidine with antihypertensive agents can result in significant hypotension. Caution is advised when tizanidine is to be used in patients receiving concurrent antihypertensive therapy.
    Tolazamide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Tolbutamide: (Moderate) Thiazide diuretics can decrease insulin sensitivity thereby leading to glucose intolerance and hyperglycemia. Diuretic-induced hypokalemia may also lead to hyperglycemia. Because of this, a potential pharmacodynamic interaction exists between thiazide diuretics and antidiabetic agents. It appears that the effects of thiazide diuretics on glycemic control are dose-related and low doses can be instituted without deleterious effects on glycemic control. In addition, diuretics reduce the risk of stroke and cardiovascular disease in patients with diabetes. However, patients taking antidiabetic agents should be monitored for changes in blood glucose control if such diuretics are added or deleted. Dosage adjustments may be necessary.
    Tolmetin: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Tolterodine: (Minor) Diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Tolvaptan: (Moderate) Monitor serum potassium concentrations after initiation of tolvaptan therapy in patients receiving angiotensin II receptor antagonists. Tolvaptan therapy results in an acute reduction in extracellular fluid volume which may result in increased serum potassium. In clinical studies, hyperkalemia was reported at a rate 1% to 2% higher when tolvaptan was administered with angiotensin II receptor blockers than when angiotensin II receptor blockers were administered with placebo. (Moderate) Monitor serum sodium closely if tolvaptan and thiazide diuretics are used together. Coadministration increases the risk of too rapid correction of serum sodium.
    Topiramate: (Major) Concurrent use or topiramate, a carbonic anhydrase inhibitor, with non-potassium sparing diuretics (e.g., thiazide diuretics) may potentiate the potassium-wasting action of these diuretics. Additionally, the addition of HCTZ to topiramate therapy may require a reduction in the topiramate dose. Alternatively, the discontinuation of HCTZ therapy may require a dose increase in topiramate. In a pharmacokinetic drug interaction study, the topiramate Cmax and AUC increased by 27% and 29% when HCTZ was added to topiramate. The clinical significance of this change is unknown. The steady-state pharmacokinetics of HCTZ were not altered to any significant degree.
    Toremifene: (Moderate) Monitor serum calcium levels in patients receiving concomitant treatment with toremifene and thiazide diuretics. Thiazide diuretics decrease renal calcium excretion and may increase the risk of hypercalcemia in patients receiving toremifene.
    Trandolapril: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Trandolapril; Verapamil: (Moderate) Patients with hyponatremia or hypovolemia are more susceptible to developing reversible renal insufficiency when given angiotensin converting enzyme (ACE) inhibitors and diuretics concomitantly.
    Tranylcypromine: (Severe) The use of hypotensive agents and tranylcypromine is contraindicated by the manufacturer of tranylcypromine because the effects of hypotensive agents may be markedly potentiated.
    Trazodone: (Minor) Due to additive hypotensive effects, patients receiving antihypertensive agents concurrently with trazodone may have excessive hypotension. Decreased dosage of the antihypertensive agent may be required when given with trazodone.
    Treprostinil: (Moderate) Thiazide diuretics can enhance the hypotensive effects of antihypertensive agents or diuretics if given concomitantly. This additive effect may be desirable, but dosages must be adjusted accordingly.
    Tretinoin, ATRA: (Moderate) A manufacturer of topical tretinoin states that tretinoin, ATRA should be administered with caution in patients who are also taking drugs known to be photosensitizers, such as thiazide diuretics, as concomitant use may augment phototoxicity. Patients should take care and use proper techniques to limit sunlight and UV exposure of treated areas.
    Triamterene: (Major) Potassium-sparing diuretics, such as triamterene, should be used with caution in patients taking drugs that may increase serum potassium levels such as angiotensin II receptor antagonists. Concurrent use can cause hyperkalemia, especially in elderly patients or patients with impaired renal function. Coadministration may also result in increases in serum creatinine in heart failure patients.
    Trihexyphenidyl: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Trimethoprim: (Moderate) Monitor for hyperkalemia if concomitant use of an angiotensin II receptor antagonist and trimethoprim is necessary. Hyperkalemia may be more significant in patients receiving IV trimethoprim. For those patients at higher risk of hyperkalemia (e.g., the elderly, patients with underlying disorders of potassium metabolism, and those with renal dysfunction), consideration of an alternate antibiotic may be warranted. Trimethoprim has a potassium-sparing effect on the distal nephron and may induce hyperkalemia, especially in those with pre-existing risk factors.
    Trospium: (Minor) Diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Tubocurarine: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Umeclidinium; Vilanterol: (Minor) Hypokalemia associated with thiazide diuretics can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is unknown, use caution when coadministering beta-agonists with thiazide diuretics and monitor serum potassium as clinically indicated.
    Valdecoxib: (Moderate) Nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the natriuretic effect of diuretics in some patients. NSAIDS have been associated with an inhibition of prostaglandin synthesis, which may result in reduced renal blood flow leading to renal insufficiency and increases in blood pressure that are often accompanied by peripheral edema and weight gain. Patients taking diuretics and NSAIDS concurrently are at higher risk of developing renal insufficiency. If an NSAID and a diuretic are used concurrently, carefully monitor the patient for signs and symptoms of decreased renal function and diuretic efficacy.
    Vecuronium: (Moderate) Concomitant administration of hydrochlorothiazide to patients receiving nondepolarizing neuromuscular blockers (e.g., tubocurarine) can cause prolonged neuromuscular blockade due to hydrochlorothiazide-induced hypokalemia. Serum potassium concentrations should be determined and corrected (if necessary) prior to initiation of neuromuscular blockade therapy.
    Venlafaxine: (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Verteporfin: (Moderate) Thiazide diuretics may cause photosensitivity and may increase the photosensitization effects of photosensitizing agents used in photodynamic therapy. Prevention of photosensitivity includes adequate protection from sources of UV radiation (e.g., avoiding sun exposure and tanning booths) and the use of protective clothing and sunscreens on exposed skin.
    Vilazodone: (Moderate) Patients receiving vilazodone with medications known to cause hyponatremia, such as diuretics, may be at increased risk of developing hyponatremia. Hyponatremia has occurred in association with the use of antidepressants such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), and mirtazapine. Hyponatremia may manifest as headache, difficulty concentrating, memory impairment, confusion, weakness, and unsteadiness which may result in falls. Severe manifestations include hallucinations, syncope, seizure, coma, respiratory arrest, and death. Symptomatic hyponatremia may require discontinuation of vilazodone, as well as implementation of the appropriate medical interventions.
    Vitamin D analogs: (Major) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
    Vitamin D: (Major) Dose adjustment of vitamin D or vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D or vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
    Vorinostat: (Moderate) Use vorinostat and thiazide diuretics together with caution; the risk of QT prolongation and arrhythmias may be increased if electrolyte abnormalities occur. Thiazide diuretics may cause electrolyte imbalances including low potassium; hypomagnesemia, hypokalemia, or hypocalcemia may increase the risk of QT prolongation with vorinostat. Frequently monitor serum electrolytes if concomitant use of these drugs is necessary.
    Vortioxetine: (Moderate) Patients receiving a diuretic during treatment with vortioxetine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Clinically significant hyponatremia has been reported during therapy with vortioxetine. One case involving serum sodium levels lower than 110 mmol/l has occurred. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of vortioxetine should be considered in patients who develop symptomatic hyponatremia.
    Yohimbine: (Moderate) Yohimbine can increase blood pressure and therefore can antagonize the therapeutic action of antihypertensive agents. Use with particular caution in hypertensive patients with high or uncontrolled blood pressure.
    Ziconotide: (Moderate) Patients taking diuretics with ziconotide may be at higher risk of depressed levels of consciousness. If altered consciousness occurs, consideration of diuretic cessation is warranted in addition to ziconotide discontinuation.
    Ziprasidone: (Minor) Monitor potassium and magnesium levels when thiazide diuretics are used during ziprasidone therapy. The risk of QT prolongation from ziprasidone is increased in the presence of hypokalemia or hypomagnesemia. (Minor) Ziprasidone is a moderate antagonist of alpha-1 receptors and may cause orthostatic hypotension with or without tachycardia, dizziness, or syncope. Additive hypotensive effects are possible if ziprasidone is used concurrently with antihypertensive agents.

    PREGNANCY AND LACTATION

    Pregnancy

    Hydrochlorothiazide; irbesartan is classified as FDA pregnancy risk category D. When used during pregnancy, drugs that affect the renin-angiotensin system (e.g., ACE inhibitors, angiotensin II receptor antagonists) can cause fetal death or injury such as hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure and death. Oligohydramnios has also been reported; it is attributed to decreased fetal renal function and results in fetal limb contractures, craniofacial deformation, and hypoplastic lung development. Retrospective data also indicate that first trimester use of ACE inhibitors has been associated with a potential risk of birth defects. However, a much larger observational study (n = 465,754) found that the risk of birth defects was similar in infants exposed to ACE inhibitors during the first trimester, in infants exposed to other antihypertensives during the first trimester, and in those whose mothers were hypertensive but were not treated. Infants born to mothers with hypertension, either treated or untreated, had a higher risk of birth defects than those born to mothers without hypertension. The authors concluded that the presence of hypertension likely contributed to the development of birth defects rather than the use of medications. Based on the results from one large study, first trimester use of thiazide and related diuretics may increase the risk for congenital defects. In addition to malformations, other fetal risks associated with thiazide use during pregnancy include hypoglycemia, thrombocytopenia, hyponatremia, hypokalemia, and death from maternal complications. Once pregnancy is detected, every effort should be made to discontinue hydrochlorothiazide; irbesartan therapy; ultrasound examination should be performed if hydrochlorothiazide; irbesartan exposure occurs beyond the first trimester. In rare cases when another antihypertensive agent cannot be used to treat a pregnant patient, serial ultrasound examinations should be performed to assess the intraamniotic environment. Closely observe newborns with histories of in utero exposure to hydrochlorothiazide; irbesartan for hypotension, oliguria, and hyperkalemia. If oliguria occurs, blood pressure and renal perfusion support may be required, as well as exchange transfusion or dialysis to reverse hypotension and/or support decreased renal function.

    According to the manufacturer, because of the potential for adverse effects on the nursing infant, a decision should be made to discontinue breast-feeding or discontinue irbesartan; hydrochlorothiazide therapy. It is not known whether irbesartan is excreted into human milk. Hydrochlorothiazide has been detected in human breast milk. The American Academy of Pediatrics (AAP) has not evaluated the use of irbesartan in breast-feeding mothers; however, the AAP does consider hydrochlorothiazide as usually compatible with breast-feeding. In addition, the ACE inhibitors captopril and enalapril are classified by the AAP as usually compatible with breast-feeding and may represent preferable alternatives in some patients. Benazepril and quinapril are excreted in human breast milk in very small quantities ; therefore, a clinically significant risk to a breast-feeding infant is not expected. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    MECHANISM OF ACTION

    The effects of hydrochlorothiazide and irbesartan on blood pressure are additive. Thiazide diuretics lower blood pressure by increasing the renal excretion of sodium; whereas irbesartan lowers blood pressure by selectively blocking the AT1 receptor in vascular and other tissues to antagonize the actions of angiotensin II, the primary vasoactive hormone of the renin-angiotensin system. Irbesartan tends to reverse the hypokalemia caused by hydrochlorothiazide; this effect is related to the dose of irbesartan.
     
    •Hydrochlorothiazide: Thiazide diuretics increase the excretion of water by inhibiting the reabsorption of sodium and chloride ions at the distal renal tubule. The natriuretic effects are accompanied by a secondary loss of potassium and bicarbonate which can cause a mild hypokalemic, hypochloremic, metabolic alkalosis. Thiazides also decrease the elimination of calcium and uric acid. Thiazides diuretics usually do not affect normal blood pressure. When chronically administered, thiazide diuretics decrease peripheral vascular resistance. The exact mechanism responsible for the lowered peripheral resistance is not known; however, excretion of urinary sodium by the kidneys is required to achieve blood pressure reduction. Initially, diuretics lower blood pressure by decreasing cardiac output, plasma volume and extracellular fluid volume. Cardiac output eventually returns to normal, plasma and extracellular fluid values return to slightly less than normal, but peripheral vascular resistance is reduced, resulting in lower blood pressure. Thiazide diuretics also decrease the glomerular filtration rate, which contributes to the drug's lower efficacy in patients with renal impairment. The changes in plasma volume induce an elevation in plasma renin activity and aldosterone secretion which contributes to the potassium losses associated with thiazide diuretics. In general, diuretics can worsen glucose tolerance and lipid abnormalities.
     
    •Irbesartan: Irbesartan selectively and competitively antagonizes the AT1 receptor in tissues such as vascular smooth muscle and the adrenal gland, thereby blocking the vasoconstrictor and aldosterone-secreting effects of angiotensin II. While ACE inhibitors inhibit the actions of angiotensin II by preventing its formation from angiotensin I, irbesartan directly antagonizes the actions of angiotensin II at the AT1 receptor site. Angiotensin II is the primary vasoactive hormone of the renin-angiotensin system and plays an important role in the pathophysiology of hypertension. Angiotensin II also stimulates aldosterone secretion by the adrenal gland. Two angiotensin II receptors, AT1 and AT2, have been identified. Irbesartan has a 8,500-fold greater affinity for the AT1 subtype than the AT2 subtype receptor. Type 1 angiotensin (AT1) receptors are found in many tissues, including vascular smooth muscle and the adrenal gland. AT2 receptors are also found in many tissues, but are not known to mediate cardiovascular homeostasis. Angiotensin II blockade results in decreased systemic vascular resistance without a marked change in heart rate. Circulating levels of both renin and angiotensin II rise 2- to 3-fold in response to blockade of AT1 receptors, but do not overcome the effects of irbesartan on blood pressure. Aldosterone plasma concentrations generally decline, but serum potassium concentrations are not significantly affected at recommended doses. Chronic administration of irbesartan has no effect on glomerular filtration rate or renal plasma flow. Similar to losartan, irbesartan has antiproteinuric effects. In contrast to losartan, irbesartan has no effect on serum uric acid. Because irbesartan does not inhibit ACE, it does not inhibit the breakdown of bradykinin. Irbesartan does not significantly affect fasting triglycerides, total cholesterol, HDL-cholesterol, or fasting glucose concentrations. Similar to ACE inhibitors, angiotensin II antagonists reduce LVH, do not worsen insulin resistance, and generally do not cause sexual dysfunction.

    PHARMACOKINETICS

    Irbesartan; hydrochlorothiazide (HCTZ) is administered orally. The blood pressure lowering effect of irbesartan is additive with that of HCTZ. No pharmacokinetic drug interaction is observed between hydrochlorothiazide and irbesartan.
    Hydrochlorothiazide: Hydrochlorothiazide  crosses the placenta, but not the blood-brain barrier, and is distributed into breast milk. Hydrochlorothiazide is not significantly metabolized and is excreted unchanged in the urine. At least 61% of the oral dose is eliminated unchanged within 24 hours. The elimination half-life ranges from 5.6—14.8 hours.
    Irbesartan: The pharmacokinetics are linear over the therapeutic dose range; however, the antihypertensive dose-response curve is nonlinear, with proportionally small decreases in blood pressure attained with increased dosage. Protein binding of irbesartan is about 90% (primarily to albumin and alpha-1-acid glycoprotein), with negligible binding to cellular components of blood. Studies in animals indicate that irbesartan weakly crosses the blood brain barrier and placenta. The parent drug is metabolized via glucuronide conjugation and oxidation. In vitro studies indicate that irbesartan is oxidized primarily by the cytochrome P450 2C9 isoenzyme; metabolism by 3A4 is negligible. Following oral or IV administration of radiolabeled irbesartan, more than 80% of the circulating plasma radioactivity is due to unchanged irbesartan. The primary circulating metabolite is the inactive irbesartan glucuronide conjugate (about 6%). Irbesartan and its metabolites are excreted by both biliary and renal routes. About 20% of a radiolabeled dose is recovered in urine and approximately 80% in the feces, as irbesartan or irbesartan glucuronide. The elimination half-life of irbesartan is about 11—15 hours.

    Oral Route

    The peak effects of hydrochlorothiazide; irbesartan on diastolic and systolic blood pressure occur at 3—6 hours following oral administration, with trough-to-peak ratios > 65%.
    Hydrochlorothiazide: Hydrochlorothiazide absorption from the GI tract varies depending on the formulation, dose, and presence of concomitant disease states. Absorption is reduced in patients with hepatic, cardiac, and/or renal disease. The bioavailability is approximately 60—70%. The onset of action is 2 hours following oral administration, with peak effects occurring at 4 hours. The duration of action ranges from 6—12 hours.
    Irbesartan: Following oral administration, absorption is rapid and complete. Absolute bioavailability is 60—80% and is not affected by food. Peak plasma concentrations are attained about 1.5—2 hours after dosing.