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  • CLASSES

    Antacids, Aluminum-based
    Astringents

    DEA CLASS

    OTC

    DESCRIPTION

    Antacid; some use for hyperphosphatemia; there is concern regarding Al++ toxicity with long-term use as a phosphate 'binder', thus use is limited to patients with high serum phosphate (7mg/dL). Not a primary treatment for PUD.

    COMMON BRAND NAMES

    Dermadrox

    HOW SUPPLIED

    Aluminum/Aluminum Hydroxide Oral Susp: 5mL, 320mg
    Aluminum/Aluminum Hydroxide/Dermadrox Topical Ointment: 1.2%

    DOSAGE & INDICATIONS

    For use as an antacid to counteract the hyperacidity associated with gastritis, peptic ulcer disease including duodenal ulcer and possibly gastric ulcer, reflux esophagitis, and hiatal hernia.
    Oral dosage (tablets, capsules)
    Adults

    NOTE: Aluminum hydroxide capsules and tablets are no longer available in the US. Dosage is variable; however, an acid neutralizing capacity of 80—140 mEq PO per dose is often required. Doses should be given every 3—6 hours, or 1 and 3 hours after meals and at bedtime. The recommended OTC dose is 600 mg PO given 5—6 times per day, after meals and at bedtime.

    Oral dosage (oral suspension)
    Adults

    Dosage is variable; however, an acid neutralizing capacity of 80—140 mEq (e.g., 40—60 mL) PO per dose is often required. Doses should be given every 3—6 hours, or 1 and 3 hours after meals and at bedtime. The recommended OTC dose is 10 mL PO 5—6 times per day, after meals and at bedtime.

    Children

    Safer and more effective alternatives exist; for use under health care professional advice only; 5—15 mL PO every 3—6 hours, or 1 and 3 hours after meals and at bedtime has been used.

    Infants

    Safer and more effective alternatives exist; for use under health care professional advice only; 1—2 mL/kg PO per dose, given 1—3 hours after meals and at bedtime, has been used.

    For the management of hyperphosphatemia secondary to renal osteodystrophy in patients with end stage renal disease.
    NOTE: Some clinicians prefer to avoid aluminum salts for this indication. Although calcium salts are preferred, aluminum salts may be desirable when serum calcium is also high. When the serum phosphate has been lowered sufficiently, aluminum salts can be replaced by calcium salts.
    Oral dosage (oral suspension)
    Adults

    300—600 mg PO, given with each meal or snack; monitor serum phosphate and titrate dosage accordingly.

    Children

    50—150 mg/kg/day PO, given in 4—6 divided doses.

    For stress gastritis prophylaxis†.
    Oral dosage (oral suspension)
    Adults

    Dosage is variable; however, an acid neutralizing capacity of 80—140 mEq (e.g., 40—60 mL) PO per dose is often required. Doses should be given every 3—6 hours, or 1—3 hours after meals and at bedtime. Dosage should be titrated according to intragastric pH.

    Children

    5—15 mL PO every 1—2 hours; titrate to gastric pH > 3.5.

    Infants

    2—5 mL PO every 1—2 hours; titrate to gastric pH > 3.5.

    Neonates

    1 mL/kg PO every 4 hours as needed.

    †Indicates off-label use

    MAXIMUM DOSAGE

    Consult package label; maximum daily dosage is age and product specific. Do not exceed recommended daily dosage in any 24 hour period.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    No specific dosage adjustment appears needed, unless the patient also has declining renal function. The daily sodium intake from the antacid may need to be considered in patients with ascites.

    Renal Impairment

    CrCl > 25 mL/min: Patients with renal impairment may be at risk of accumulating aluminum. However, no dosage guidelines are available.
    CrCl 10—25 mL/min: Patients with renal impairment may be at risk of accumulating aluminum. However, no dosage guidelines are available; dosage should be modified depending on clinical response and evidence of aluminum accumulation.
    CrCl < 10 mL/min: While aluminum hydroxide has been used historically in patients with ESRD as a dietary phosphate-binder, avoid use in renal failure due to the potential for aluminum accumulation. If aluminum hydroxide must be used, the dosage should be modified depending on clinical response and evidence of aluminum accumulation.

    ADMINISTRATION

    Oral Administration

    Do not administer concurrently with other oral medications; see Drug Interactions for specific guidance on dosing separation.

    Oral Solid Formulations

    Capsules and tablets: Administer whole with a glass of water. Do not suck on or chew the tablets.

    Oral Liquid Formulations

    NOTE: Aluminum hydroxide suspension is available in several different concentrations. For individual composition see Product Information. Suspensions have a greater acid neutralizing capacity (ANC) than tablets or capsules because suspensions are more rapidly and effectively solubilized. Amphojel suspension has an ANC of 10 mEq/5mL. Amphojel tablets and Alu-Cap capsules have an ANC of 8 mEq/300 mg tablet and 8.5 mEq/400 mg capsule, respectively.
    Oral suspensions: Shake well prior to administration. Measure dosage with a calibrated device. Follow dose with a glass of water.

    STORAGE

    Generic:
    - Protect from freezing
    - Store at controlled room temperature (between 68 and 77 degrees F)
    Alternagel:
    - Do not freeze
    Dermadrox:
    - Store at room temperature (between 59 to 86 degrees F)

    CONTRAINDICATIONS / PRECAUTIONS

    Hypophosphatemia

    Aluminum hydroxide is relatively contraindicated in patients with hypophosphatemia. Aluminum hydroxide binds with dietary phosphate in the gut, impairing its absorption. Rarely, patients with normal blood phosphate may develop hypophosphatemia if phosphate intake is not appropriate.

    Diarrhea

    Aluminum hydroxide should be used cautiously in patients with chronic diarrhea. Although the constipating effects of aluminum hydroxide may correct the diarrhea, diarrhea increases the risk of developing hypophosphatemia associated with the use of aluminum.

    Anticholinergic medications, constipation, dehydration, fecal impaction, GI bleeding, GI obstruction, hemorrhoids, ileus

    Aluminum hydroxide causes constipation and should be used with extreme caution in patients who are predisposed to constipation or complications associated with constipation, including patients receiving antidiarrheals or anticholinergic medications, and patients with gastric outlet obstruction. Patients with constipation, fecal impaction, GI obstruction, ileus, hemorrhoids, or undiagnosed rectal or GI bleeding should receive aluminum hydroxide with caution; it is possible that these conditions could be aggravated or the patient could develop sepsis, peritonitis, or ischemic bowel. Patients with dehydration, who are fluid restricted, or have preexisting decreased bowel motility are predisposed to developing GI obstruction with the use of aluminum hydroxide.

    Neonates, renal disease, renal failure, renal impairment

    Aluminum hydroxide should be used cautiously in neonates and in patients with renal impairment or renal disease because of the increased risk of developing aluminum toxicity. Dialysis-associated dementia or encephalopathy may occur in dialysis patients with long term use of aluminum-containing drugs. Do not use in patients with renal failure unless they are being closely monitored for signs and symptoms of toxicity.

    Ascites, heart failure, hepatic disease

    Use aluminum hydroxide products with caution in patients on sodium restricted diets and in those with congestive heart failure, renal failure, edema, renal disease, or cirrhosis with ascites (severe hepatic disease) as the total daily dose may exceed 5 mEq (115 mg) of sodium.

    Geriatric

    Use aluminum hydroxide with caution in geriatric patients. Elderly patients are predisposed to constipation and typically have a declining renal function, putting them at an increased risk for problems associated with aluminum induced constipation and aluminum toxicity.

    Colostomy, diverticulitis, ileostomy

    Aluminum hydroxide is relatively contraindicated in patients with colostomy, diverticulitis, or ileostomy because the drug increases the risk of developing electrolyte imbalance.

    Pregnancy

    A specific FDA pregnancy risk category has not been assigned to aluminum hydroxide. When chronic use and high doses are avoided, aluminum hydroxide appears to be safe and effective for the occasional relief of dyspepsia and pyrosis in the mother during pregnancy. When used occasionally at recommended doses, aluminum containing antacids have not been found to produce teratogenic effects and are generally considered safe during pregnancy, provided the pregnant woman does not have concerns with renal dysfunction. Increased tendon reflexes have been reported in newborns whose mothers were using aluminum containing antacid products chronically and in high doses during their pregnancy. It may be advisable to consider a combination antacid rather than aluminum hydroxide alone for relief of dyspepsia or pyrosis during pregnancy as the combination antacids allow for comparative relief of symptoms at lower doses.

    Children, infants

    Over-the-counter use of aluminum hydroxide is not recommended as an antacid in infants and children < 2 years without supervision of a physician due to the serious nature of the complications associated with reflux in infants (such as failure to thrive, esophageal stricture, Barrett's esophagus, intraesophageal polyps, and associated pulmonary diseases). Aluminum hydroxide has been used in children for esophagitis and peptic ulcer disease, although safety has not been clearly established.

    Breast-feeding

    When chronic use and high doses are avoided, aluminum hydroxide appears to be safe and effective for the occasional relief of dyspepsia and pyrosis in the mother during breast-feeding. Aluminum does not enter breast milk significantly, and no problems have been reported during breast-feeding. It may be advisable to consider a combination antacid rather than aluminum hydroxide alone for relief of dyspepsia or pyrosis while breast-feeding, as the combination antacids allow for comparative relief of symptoms at lower doses.

    ADVERSE REACTIONS

    Severe

    GI obstruction / Delayed / Incidence not known

    Moderate

    hemorrhoids / Delayed / Incidence not known
    constipation / Delayed / Incidence not known
    osteomalacia / Delayed / Incidence not known
    encephalopathy / Delayed / Incidence not known
    impaired cognition / Early / Incidence not known
    osteoporosis / Delayed / Incidence not known
    hypophosphatemia / Delayed / Incidence not known
    nephrolithiasis / Delayed / Incidence not known
    hypercalcemia / Delayed / Incidence not known

    Mild

    weakness / Early / Incidence not known
    malaise / Early / Incidence not known
    anorexia / Delayed / Incidence not known

    DRUG INTERACTIONS

    Abacavir; Dolutegravir; Lamivudine: (Moderate) Administer dolutegravir 2 hours before or 6 hours after taking cation-containing antacids. The chemical structure of these antacids contain aluminum which can bind dolutegravir in the GI tract. Taking these drugs simultaneously may result in reduced bioavailability of dolutegravir.
    Acalabrutinib: (Moderate) Separate the administration of acalabrutinib and antacids by at least 2 hours if these agents are used together. Acalabrutinib solubility decreases with increasing pH values; therefore, coadministration may result in decreased acalabrutinib exposure and effectiveness. In healthy subjects, the AUC of acalabrutinib was decreased by 53% when acalabrutinib was coadministered with another antacid.
    Acetaminophen: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Aspirin, ASA; Caffeine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Butalbital: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Butalbital; Caffeine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Butalbital; Caffeine; Codeine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Caffeine; Dihydrocodeine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected. (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Codeine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Dextromethorphan: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Dextromethorphan; Doxylamine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Dextromethorphan; Phenylephrine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Dextromethorphan; Pseudoephedrine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected. (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Acetaminophen; Dichloralphenazone; Isometheptene: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Diphenhydramine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Guaifenesin; Phenylephrine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Hydrocodone: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Oxycodone: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Pentazocine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Propoxyphene: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acetaminophen; Pseudoephedrine: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected. (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Acetaminophen; Tramadol: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Acidifying Agents: (Major) Aluminum hydroxide and magnesium hydroxide (as well as other antacids, i.e. aluminum hydroxide; magnesium carbonate, aluminum hydroxide; magaldrate; magnesium hydroxide, and aluminum hydroxide; magnesium trisilicate) may interact with urinary acidifiers by alkalinizing the urine. Frequent use of these high dose antacids should be avoided in patients receiving urinary acidifiers.
    Acrivastine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Alendronate; Cholecalciferol: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Allopurinol: (Minor) Aluminum hydroxide decreases the oral bioavailability of allopurinol, possibly by inhibiting gastrointestinal absorption of allopurinol. Allopurinol should be administered no less than 3 hours before doses of aluminum hydroxide to avoid inhibition of allopurinol absorption.
    Amlodipine; Atorvastatin: (Moderate) Concomitant administration of atorvastatin with antacids reduced the plasma concentrations of atorvastatin by approximately 35 percent. However, LDL-cholesterol reduction was not altered.
    Amphetamines: (Major) Concurrent use of amphetamines and gastrointestinal alkalinizers, such as antacids (e.g., calcium carbonate, magnesium oxide, sodium bicarbonate), should be avoided. An alkaline environment increases the absorption of amphetamines. In addition, antacids act as urinary alkalinizers, which diminishes the urinary excretion of amphetamines. Urinary alkalinizers increase the proportion of non-ionized amphetamines, resulting in increased renal tubular reabsorption of these compounds. The half-life and therapeutic actions of amphetamines will be prolonged in the presence of these drugs.
    Amprenavir: (Moderate) Coadministration with antacids decreases amprenavir plasma concentrations. It is recommended that the administration of amprenavir and antacids be separated by at least 1 hour.
    Anticholinergics: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Ascorbic Acid, Vitamin C: (Minor) Because antacids can alkalinize the urine, they can interact with urinary acidifiers, such as ascorbic acid. Frequent use of high doses of antacids should be avoided by patients receiving urinary acidifiers.
    Atazanavir: (Major) It is recommended that antacids not be given at the some time as atazanavir because of potential interference with absorption of atazanavir. Separate the administration of atazanavir and antacids to avoid the potential for interaction; give atazanavir 2 hours before or 1 hour after the antacid.
    Atazanavir; Cobicistat: (Major) It is recommended that antacids not be given at the some time as atazanavir because of potential interference with absorption of atazanavir. Separate the administration of atazanavir and antacids to avoid the potential for interaction; give atazanavir 2 hours before or 1 hour after the antacid.
    Atenolol: (Minor) Aluminum hydroxide antacids have been reported to decrease atenolol mean peak concentrations by about 20% and the AUC of atenolol by 57%. In another study, antacids have been shown to reduce the AUC of atenolol by 33%. Separate doses of atenolol and aluminum-containing antacids or supplements when possible by at least 2 hours to minimize this potential interaction. However, most clinicians consider the interaction of atenolol with antacids to be of minor clinical significance, since clinical efficacy (heart rate and blood pressure parameters) appear to be unchanged under usual intermittent clinical use.
    Atenolol; Chlorthalidone: (Minor) Aluminum hydroxide antacids have been reported to decrease atenolol mean peak concentrations by about 20% and the AUC of atenolol by 57%. In another study, antacids have been shown to reduce the AUC of atenolol by 33%. Separate doses of atenolol and aluminum-containing antacids or supplements when possible by at least 2 hours to minimize this potential interaction. However, most clinicians consider the interaction of atenolol with antacids to be of minor clinical significance, since clinical efficacy (heart rate and blood pressure parameters) appear to be unchanged under usual intermittent clinical use.
    Atorvastatin: (Moderate) Concomitant administration of atorvastatin with antacids reduced the plasma concentrations of atorvastatin by approximately 35 percent. However, LDL-cholesterol reduction was not altered.
    Atorvastatin; Ezetimibe: (Moderate) Concomitant administration of atorvastatin with antacids reduced the plasma concentrations of atorvastatin by approximately 35 percent. However, LDL-cholesterol reduction was not altered. (Minor) Antacids may decrease the peak plasma concentration (Cmax) of total ezetimibe by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) The therapeutic action of methenamine requires an acidic urine. Antacids containing alkalinizing agents such as sodium bicarbonate can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
    Azithromycin: (Moderate) Antacids containing aluminum salts and/or magnesium salts can decrease the oral absorption of immediate-release azithromycin, resulting in lower peak plasma concentrations. If antacids must be taken, stagger the administration of the antacid and azithromycin. The extended-release suspension may be taken without regard to antacids containing magnesium hydroxide and/or aluminum hydroxide.
    Baloxavir Marboxil: (Major) Do not administer baloxavir with products that contain aluminum hydroxide. Polyvalent cations, such as aluminum, can chelate with baloxavir; thereby reducing its absorption.
    Benzhydrocodone; Acetaminophen: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) The therapeutic action of methenamine requires an acidic urine. Antacids containing alkalinizing agents such as sodium bicarbonate can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
    Bictegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) Routine administration of bictegravir simultaneously with, or 2 hours after, antacids containing aluminum or magnesium is not recommended as the bioavailability of bictegravir may be reduced. Administer bictegravir on an empty stomach 2 hours before antacids containing aluminum or magnesium. In drug interaction studies, simultaneous administration of bictegravir and antacids under fasted and fed conditions decreased the mean AUC of bictegravir by approximately 79% and 47%, respectively.
    Bisacodyl: (Minor) The concomitant use of bisacodyl tablets with antacids can cause the enteric coating of the bisacody tablet to dissolve prematurely, leading to possible gastric irritation or dyspepsia. Avoid antacids within 1 hour before or after the bisacodyl dosage.
    Bismuth Subcitrate Potassium; Metronidazole; Tetracycline: (Moderate) Separate administration of tetracycline and antacids by 2 to 3 hours. Coadministration may impair absorption of tetracycline which may decrease its efficacy.
    Bismuth Subsalicylate; Metronidazole; Tetracycline: (Moderate) Separate administration of tetracycline and antacids by 2 to 3 hours. Coadministration may impair absorption of tetracycline which may decrease its efficacy.
    Bisphosphonates: (Moderate) Separating times of administration of the oral bisphosphonate from aluminum-containing medications will maximize absorption and clinical benefit. Aluminum hydroxide will interfere with the absorption of the orally administered bisphosphonates alendronate, etidronate, ibandronate, risedronate, and tiludronate. At least 30 minutes should elapse after the oral administration of alendronate before taking any aluminum containing product. At least 1 hour should elapse after the oral administration of ibandronate before taking any aluminum containing product. At least 2 hours should elapse after the oral administration of etidronate, risedronate, or tiludronate before administering any aluminum containing product.
    Bosutinib: (Moderate) Bosutinib displays pH-dependent aqueous solubility; therefore, concomitant use of bosutinib and antacids may result in decreased plasma exposure of bosutinib. Separate the administration of bosutinib and antacids by more than 2 hours.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Brompheniramine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Budesonide: (Major) Enteric-coated budesonide granules dissolve at a pH > 5.5. Likewise, the dissolution of the coating of extended-release budesonide tablets (Uceris) is pH dependent. Concomitant use of oral budesonide and antacids, milk, or other drugs that increase gastric pH levels can cause the coating of the granules to dissolve prematurely, possibly affecting release properties and absorption of the drug in the duodenum. In general, it may be prudent to avoid drugs such as antacids in combination with enteric-coated budesonide.
    Budesonide; Formoterol: (Major) Enteric-coated budesonide granules dissolve at a pH > 5.5. Likewise, the dissolution of the coating of extended-release budesonide tablets (Uceris) is pH dependent. Concomitant use of oral budesonide and antacids, milk, or other drugs that increase gastric pH levels can cause the coating of the granules to dissolve prematurely, possibly affecting release properties and absorption of the drug in the duodenum. In general, it may be prudent to avoid drugs such as antacids in combination with enteric-coated budesonide.
    Calcium; Vitamin D: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Capecitabine: (Minor) When an aluminum hydroxide containing antacid was administered immediately after capecitabine, AUC and Cmax increased for capecitabine and for the metabolite 5'-DFCR. No effect was observed on the other three major metabolites of capecitabine (5'-DFUR, 5-FU, FBAL). Because the pharmacokinetic parameters of 5-FU were not affected, the clinical relevance of this interaction may be minor.
    Captopril: (Major) Antacids can decrease the GI absorption of captopril if administered simultaneously.
    Captopril; Hydrochlorothiazide, HCTZ: (Major) Antacids can decrease the GI absorption of captopril if administered simultaneously.
    Carbetapentane; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Carbinoxamine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Cardiac glycosides: (Moderate) Concurrent administration of liquid antacid formulations of aluminum hydroxide can decrease absorption of digoxin and other cardiac glycosides and reduce their plasma concentration. Steady state concentrations of digoxin are not lowered following administration of tablet formulations of aluminum hydroxide. Doses of liquid aluminum hydroxide and cardiac glycosides should be spaced 1 to 2 hours apart. The manufacturer of digoxin recommends measuring serum digoxin concentrations prior to initiation of an antacid. Continue monitoring during concomitant treatment and increase the digoxin dose by 20 to 40% as necessary.
    Cefdinir: (Major) Antacids containing magnesium or aluminum can interfere with the absorption of cefdinir. If aluminum or magnesium containing antacids are required during cefdinir therapy, cefdinir should be taken at least 2 hours before or after the antacid.
    Cefditoren: (Major) Separate the administration of cefditoren and magnesium- or aluminum-containing antacids by at least 2 hours. Coadministration interferes with cefditoren absorption causing a decrease in the Cmax and AUC. Other orally administered aluminum or magnesium salts may also interfere with cefditoren absorption.
    Cefpodoxime: (Moderate) Cefpodoxime proxetil requires a low gastric pH for dissolution; therefore, concurrent administration with medications that increase gastric pH (e.g., antacids) may decrease the bioavailability of cefpodoxime. Concomitant administration with high doses of antacids reduces peak plasma concentrations by 24% and the extent of absorption by 27%. The rate of absorption is not affected.
    Cefuroxime: (Moderate) Antacids can interfere with the oral absorption of cefuroxime axetil and may result in reduced antibiotic efficacy. If an antacid must be used while a patient is taking cefuroxime, administer the oral dosage of cefuroxime at least 1 hour before or 2 hours after the antacid.
    Ceritinib: (Moderate) Use caution if the concomitant use of ceritinib with antacids is necessary, as the bioavailability of ceritinib may be reduced. Ceritinib displays pH-dependent solubility with decreased solubility at a higher pH, but data are conflicting regarding clinical significance. In healthy subjects, the AUC and Cmax of ceritinib decreased by 76% and 79%, respectively, when a single dose was administered with esomeprazole. However, in a subgroup of patients with NSCLC from a multicenter, open-label clinical trial, the AUC and Cmax of ceritinib decreased by 30% and 25%, respectively, after a single dose was administered with proton pump inhibitors; there was no clinically meaningful effect on ceritinib exposure at steady state.
    Cetirizine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chenodiol: (Moderate) Aluminum hydroxide based antacids have been shown to adsorb bile acids in vitro and are expected to interfere with the efficacy of chenodiol. To minimize drug interactions, administer chenodiol at least 1 hour before or at least 2 hours after the aluminum-based antacid.
    Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chloroquine: (Major) Chloroquine absorption may be reduced by antacids. Administer chloroquine and antacids at least 4 hours apart.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpromazine: (Moderate) The absorption of chlorpromazine liquids, suspensions, or concentrates may be decreased by co-administration of antacids. It may be advisable to separate chlorpromazine administration from antacids by 1 to 2 hours. In a small study (n = 6), administration of a magnesium trisilicate and aluminum hydroxide liquid gel antacid with a chlorpromazine liquid suspension resulted in a statistically significant decrease in chlorpromazine concentrations (average 20% decline; approximate range: 6% to 48%). In another kinetic study (n = 10), concurrent use of chlorpromazine liquid concentrate and an aluminum and magnesium hydroxide suspension reduced the urinary excretion of chlorpromazine by 10% to 45%. Adsorption of chlorpromazine to the antacid suspension may have contributed to a subsequent decline in urinary excretion of the drug.
    Cholic Acid: (Moderate) Do not administer cholic acid simultaneously with aluminum-based antacids (i.e. aluminum hydroxide) because a reduction in cholic acid absorption will occur. Administer cholic acid at least 1 hour before or 4 to 6 hours (or the maximal interval possible) after an aluminum-based antacids.
    Chondroitin; Glucosamine: (Minor) Because antacids can alkalinize the urine, they can interact with urinary acidifiers, such as ascorbic acid. Frequent use of high doses of antacids should be avoided by patients receiving urinary acidifiers.
    Ciprofloxacin: (Major) Administer oral ciprofloxacin at least 2 hours before or 6 hours after products that contain aluminum hydroxide. Ciprofloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids that contain aluminum hydroxide.
    Citric Acid; Potassium Citrate: (Major) Avoid coadministration of aluminum hydroxide with citrate salts due to the potential for increased absorption of aluminum. Patients at increased risk of aluminum accumulation include patients with renal impairment or renal failure.
    Citric Acid; Potassium Citrate; Sodium Citrate: (Severe) Avoid coadministration of antacids with citrate salts since increased absorption of aluminum can occur. In addition, some antacids like calcium carbonate, share the potential with the citrate salts for development of metabolic alkalosis, when given in higher dosage. (Major) Avoid coadministration of aluminum hydroxide with citrate salts due to the potential for increased absorption of aluminum. Patients at increased risk of aluminum accumulation include patients with renal impairment or renal failure.
    Citric Acid; Sodium Citrate: (Severe) Avoid coadministration of antacids with citrate salts since increased absorption of aluminum can occur. In addition, some antacids like calcium carbonate, share the potential with the citrate salts for development of metabolic alkalosis, when given in higher dosage.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) Separate administration of elvitegravir and antacids by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Separate administration of elvitegravir and antacids by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
    Cod Liver Oil: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure. (Moderate) The chronic use of aluminum-containing antacids for hyperphosphatemia in conjunction with vitamin D, as contained in cod liver oil, can lead to aluminum retention and possible toxicity.
    Collagenase: (Minor) Because antacids can alkalinize the urine, they can interact with urinary acidifiers, such as ascorbic acid. Frequent use of high doses of antacids should be avoided by patients receiving urinary acidifiers.
    Conjugated Estrogens; Bazedoxifene: (Minor) In clinical evaluation, a single dose of 460 mg aluminum hydroxide and 400 mg magnesium hydroxide was given with a bazedoxifene 40 mg tablet in 30 postmenopausal women after an overnight fast. Coadministration of aluminum/magnesium hydroxide and bazedoxifene decreased Cmax of bazedoxifene by 8% and increased AUC of bazedoxifene by 7%. The clinical effect of this change is not known, but appears to be clinically insignificant. Separating times of administration may help limit any possible interaction.
    Cranberry, Vaccinium macrocarpon Ait.: (Minor) Because antacids can alkalinize the urine, they can interact with urinary acidifiers, such as ascorbic acid. Frequent use of high doses of antacids should be avoided by patients receiving urinary acidifiers.
    Dasatinib: (Moderate) Separate the administration of dasatinib and antacids by at least 2 hours if these agents are used together. The simultaneous administration of an antacid with dasatinib decreased the Cmax and AUC of dasatinib by 58% and 55%, respectively.
    Deferasirox: (Moderate) Although deferasirox has a lower affinity for aluminum than for iron, deferasirox may also increase the excretion of aluminum. Because deferasirox may bind to aluminum instead of iron, aluminum containing antacids should not be administered concurrently in order to avoid a possible decreased efficacy of either therapy.
    Deferiprone: (Moderate) Concurrent use of deferiprone with food, mineral supplements, and antacids that contain polyvalent (trivalent) cations has not been studied. However, since deferiprone has the potential to bind polyvalent cations (e.g., iron, aluminum, and zinc), allow at least a 4-hour interval between deferiprone and other medications or dietary supplements containing these polyvalent cations. Such medications can include antacids, iron salts, aluminum hydroxide, dietary supplements containing polyvalent minerals, and zinc salts.
    Delafloxacin: (Major) Administer oral delafloxacin at least 2 hours before or 6 hours after products that contain aluminum hydroxide. Delafloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids containing aluminum hydroxide.
    Delavirdine: (Major) Coadministration of delavirdine with antacids results in decreased absorption of delavirdine. Administration of delavirdine and antacids should be separated by at least 1 hour.
    Demeclocycline: (Moderate) Separate administration of demeclocycline and antacids by 2 to 3 hours. Coadministration may impair absorption of demeclocycline which may decrease its efficacy.
    Desloratadine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Dexmethylphenidate: (Minor) The effects of gastrointestinal pH alterations on the absorption of extended-release dexmethylphenidate (Focalin XR) have not been studied. Per the manufacturer of extended-release dexmethylphenidate, the modified release characteristics are pH-dependent. It is possible that the administration of antacids or other acid suppressants could alter the release of extended-release dexmethylphenidate, resulting in reduced or increased absorption. Patients receiving an antacid should be monitored for adverse effects and reduced therapeutic efficacy of extended-release dexmethylphenidate.
    Dextromethorphan; Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Dextromethorphan; Quinidine: (Major) Alkalinizing agents such as antacids can increase renal tubular reabsorption of quinidine by alkalinizing the urine; higher quinidine serum concentrations and quinidine toxicity are possible.
    Diazepam: (Moderate) The coadministration of diazepam with antacids results in delayed diazepam absorption due to the fact that antacids delay gastric emptying. It may be prudent to separate dosing by 2 hours to limit any potential interaction.
    Didanosine, ddI: (Minor) The side effects associated with aluminum hydroxide may potentially be increased during concurrent use with didanosine, ddI because some ddI products also contain similar antacid ingredients.
    Diflunisal: (Moderate) Concurrent use of diflunisal with antacids may reduce plasma diflunisal concentrations. The effect may be clinically significant if antacids are used on a continuous schedule.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Diphenhydramine; Naproxen: (Minor) Concomitant administration of antacids can delay the absorption of naproxen. Periodic antacid use should not be problematic as long as the antacid and enteric-coated naproxen administration are separated by at least 2 hours.
    Dirithromycin: (Minor) Antacids can interfere with the absorption of dirithromycin. If antacids must be used while a patient is taking these antibiotics, separate the administration by at least 2 hours.
    Dolutegravir: (Moderate) Administer dolutegravir 2 hours before or 6 hours after taking cation-containing antacids. The chemical structure of these antacids contain aluminum which can bind dolutegravir in the GI tract. Taking these drugs simultaneously may result in reduced bioavailability of dolutegravir.
    Dolutegravir; Rilpivirine: (Moderate) Administer dolutegravir 2 hours before or 6 hours after taking cation-containing antacids. The chemical structure of these antacids contain aluminum which can bind dolutegravir in the GI tract. Taking these drugs simultaneously may result in reduced bioavailability of dolutegravir. (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Doxycycline: (Moderate) Separate administration of doxycycline and antacids by 2 to 3 hours. Coadministration may impair absorption of doxycycline which may decrease its efficacy.
    Eltrombopag: (Major) Eltrombopag chelates polyvalent cations (e.g., calcium, aluminum, and magnesium) in food, mineral supplements, and antacids. In a clinical study, systemic exposure to eltrombopag was decreased by 70% when it was administered with a polyvalent cation-containing antacid. Administer eltrombopag at least 2 hours before or 4 hours after any oral products containing polyvalent cations, such as aluminum salts, (like aluminum hydroxide), calcium salts, (including calcium carbonate), and magnesium salts.
    Elvitegravir: (Moderate) Separate administration of elvitegravir and antacids by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
    Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Emtricitabine; Rilpivirine; Tenofovir disoproxil fumarate: (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Ergocalciferol, Vitamin D2: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Erlotinib: (Major) Separate administration by several hours if concomitant use of erlotinib and antacids is necessary. Erlotinib displays pH-dependent solubility with decreased solubility at a higher pH; the increased gastric pH resulting from antacid therapy may reduce the bioavailability of erlotinib. Increasing the dose of erlotinib without modifying the administration schedule is unlikely to compensate for loss of exposure. The effects of antacids on erlotinib pharmacokinetics has not been evaluated.
    Esomeprazole; Naproxen: (Minor) Concomitant administration of antacids can delay the absorption of naproxen. Periodic antacid use should not be problematic as long as the antacid and enteric-coated naproxen administration are separated by at least 2 hours.
    Ethambutol: (Moderate) Aluminum hydroxide can reduce the rate or extent of ethambutol absorption. At least 4 hours should elapse between doses of aluminum hydroxide-containing antacids and ethambutol.
    Ethinyl Estradiol; Norethindrone Acetate; Ferrous fumarate: (Major) Antacids may decrease the absorption of oral iron preparations. At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Ethinyl Estradiol; Norethindrone; Ferrous fumarate: (Major) Antacids may decrease the absorption of oral iron preparations. At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Ethotoin: (Major) Aluminum hydroxide inhibits the absorption of ethotoin. Simultaneous administration should be avoided; separate dosing by at least 2 hours to limit an interaction.
    Ezetimibe: (Minor) Antacids may decrease the peak plasma concentration (Cmax) of total ezetimibe by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Ezetimibe; Simvastatin: (Minor) Antacids may decrease the peak plasma concentration (Cmax) of total ezetimibe by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Fexofenadine: (Major) Coadministration with antacids (containing aluminum or magnesium) within 15 minutes decreases the AUC and Cmax of fexofenadine by 41% and 43%, respectively. Separate administration is recommended.
    Fexofenadine; Pseudoephedrine: (Major) Coadministration with antacids (containing aluminum or magnesium) within 15 minutes decreases the AUC and Cmax of fexofenadine by 41% and 43%, respectively. Separate administration is recommended. (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Fish Oil, Omega-3 Fatty Acids (Dietary Supplements): (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Fosamprenavir: (Moderate) The administration of an aluminum hydroxide and magnesium hydroxide containing antacid with fosamprenavir decreased fosamprenavir Cmax and AUC. It is recommended that the administration of fosamprenavir and antacids be separated by at least 1 hour.
    Fosinopril: (Moderate) Coadministration of antacids with fosinopril may impair absorption of fosinopril. Therefore, if concomitant administration of these agents is indicated, dosing should be separated by 2 hours.
    Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Coadministration of antacids with fosinopril may impair absorption of fosinopril. Therefore, if concomitant administration of these agents is indicated, dosing should be separated by 2 hours.
    Gabapentin: (Major) Antacids have been shown to reduce the oral bioavailability of gabapentin by roughly 20%. This decrease in bioavailability was about 5% when gabapentin was administered 2 hours after the antacid. It is recommended that gabapentin be taken at least 2 hours following the administration of antacids in order to avoid a significant interaction.
    Gastrointestinal Enzymes: (Major) The effectiveness of gastrointestinal enzymes can be diminished with concurrent administration of antacids. In-vitro studies suggest that calcium and magnesum cations exert their deleterious effect on replacement enzyme therapy by formation of poorly soluble calcium or magnesium soaps and precipitation of glycine conjugated bile salts.
    Gefitinib: (Major) Avoid coadministration of antacids with gefitinib if possible due to decreased exposure to gefitinib, which may lead to reduced efficacy. If concomitant use is unavoidable, take gefitinib 6 hours after the last dose or 6 hours before the next antacid dose. Gefitinib exposure is affected by gastric pH. Coadministration with another drug to maintain gastric pH above 5 decreased gefitinib exposure by 47%.
    Gemifloxacin: (Major) Administer products that contain aluminum hydroxide at least 3 hours before or 2 hours after gemifloxacin. Gemifloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids that contain aluminum hydroxide.
    Glipizide: (Moderate) Antacids have been reported to increase the absorption of glipizide, enhancing its hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. If these drugs must be used together, give glipizide at least 2 hours prior to the antacid. Consider closely monitoring blood glucose concentrations.
    Glipizide; Metformin: (Moderate) Antacids have been reported to increase the absorption of glipizide, enhancing its hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. If these drugs must be used together, give glipizide at least 2 hours prior to the antacid. Consider closely monitoring blood glucose concentrations.
    Glyburide: (Moderate) Antacids have been reported to increase the absorption of non-micronized glyburide, enhancing their hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. If antacids must be used while a patient is taking glyburide, give the glyburide at least 2 hours prior to the antacid. Consider closely monitoring blood glucose concentrations.
    Glyburide; Metformin: (Moderate) Antacids have been reported to increase the absorption of non-micronized glyburide, enhancing their hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. If antacids must be used while a patient is taking glyburide, give the glyburide at least 2 hours prior to the antacid. Consider closely monitoring blood glucose concentrations.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Halofantrine: (Major) The oral absorption of halofantrine may be hindered by the concomitant use of antacids, and perhaps other antacids. Stagger the administration of halofantrine and antacids by at least 2 hours to limit an interaction.
    Hydrochlorothiazide, HCTZ; Propranolol: (Major) Antacids may reduce the absorption of propranolol. The need to stagger doses of propranolol has not been established, but may be prudent. Monitor clinical response, and adjust propranolol dosage if needed to attain therapeutic goals.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Hydroxychloroquine: (Major) Hydroxychloroquine absorption may be reduced by antacids as has been observed with the structurally similar chloroquine. Administer hydroxychloroquine and antacids at least 4 hours apart. Of note, a study demonstrated no significant difference in hydroxychloroquine serum concentration in patients taking concomitant antacids (n = 14) compared to those not taking antacids (n = 495).
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Major) The therapeutic action of methenamine requires an acidic urine. Antacids containing alkalinizing agents such as sodium bicarbonate can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
    Ibuprofen; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Indomethacin: (Moderate) Antacids may inhibit the oral absorption of indomethacin. Simultaneous administration should be avoided; separate dosing by at least 2 hours to limit an interaction.
    Iron Salts: (Major) Antacids may decrease the absorption of oral iron preparations. At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Iron: (Major) Antacids may decrease the absorption of oral iron preparations. At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Moderate) Concomitant use of antacids and rifampin may decrease the absorption of rifampin. Daily doses of rifampin should be given at least 1 hour before the ingestion of antacids.
    Isoniazid, INH; Rifampin: (Moderate) Concomitant use of antacids and rifampin may decrease the absorption of rifampin. Daily doses of rifampin should be given at least 1 hour before the ingestion of antacids.
    Itraconazole: (Moderate) When administering antacids with the 100 mg itraconazole capsule and 200 mg itraconazole tablet formulations, systemic exposure to itraconazole is decreased. Conversely, exposure to itraconazole is increased when antacids are administered with the 65 mg itraconazole capsule. Administer antacids at least 2 hours before or 2 hours after the 100 mg capsule or 200 mg tablet. Monitor for increased itraconazole-related adverse effects if antacids are administered with itraconazole 65 mg capsules.
    Ketoconazole: (Major) Ketoconazole requires an acidic pH for absorption. Medications that increase gastric pH or decrease acid output can cause a notable decrease in the bioavailability of ketoconazole. Medications that have this effect are antacids, antimuscarinics, histamine H2-blockers, and proton pump inhibitors (PPIs). Except for antacids, these medications have a prolonged duration of action, and staggering their time of administration with ketoconazole by several hours may not prevent the drug interaction; ketoconazole should be administered at least 2 hours before or 1 hour after antacids. An alternative imidazole antifungal should be chosen if any of these gastrointestinal medications are required. If these drugs must be coadministered, administer ketoconazole tablets with an acidic beverage and closely monitor for breakthrough infection.
    Lactulose: (Major) In general, other laxatives should not be used concurrently with lactulose, especially during the initial phase of therapy for portal-systemic encephalopathy, because the loose stools resulting from their use may falsely suggest that adequate lactulose dosage has been achieved. Studies suggest that oral, nonabsorbable antacids and/or laxatives like magnesium hydroxide can interfere with the decrease in colon pH necessary for lactulose's action and these alterations may make it challenging to titrate an accurate dose of lactulose during treatment of hepatic encephalopathy.
    Lansoprazole; Naproxen: (Minor) Concomitant administration of antacids can delay the absorption of naproxen. Periodic antacid use should not be problematic as long as the antacid and enteric-coated naproxen administration are separated by at least 2 hours.
    Ledipasvir; Sofosbuvir: (Moderate) Separate administration of ledipasvir and antacids by at least 4 hours. Solubility of ledipasvir decreases as gastric pH increases; thus, simultaneous administration of these drugs may result in lower ledipasvir plasma concentrations.
    Lesinurad; Allopurinol: (Minor) Aluminum hydroxide decreases the oral bioavailability of allopurinol, possibly by inhibiting gastrointestinal absorption of allopurinol. Allopurinol should be administered no less than 3 hours before doses of aluminum hydroxide to avoid inhibition of allopurinol absorption.
    Levofloxacin: (Major) Administer products that contain aluminum hydroxide at least 2 hours before or 2 hours after orally administered levofloxacin. Levofloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Chelation of divalent cations with levofloxacin is less than with other quinolones. Examples of compounds that may interfere with quinolone bioavailability include antacids that contain aluminum hydroxide.
    Levothyroxine: (Major) Aluminum hydroxide interferes with the intestinal absorption of thyroid hormones. To minimize this interaction, administer thyroid hormones at least 4 hours before or after antacids or other drugs containing aluminum.
    Levothyroxine; Liothyronine (Porcine): (Major) Aluminum hydroxide interferes with the intestinal absorption of thyroid hormones. To minimize this interaction, administer thyroid hormones at least 4 hours before or after antacids or other drugs containing aluminum.
    Levothyroxine; Liothyronine (Synthetic): (Major) Aluminum hydroxide interferes with the intestinal absorption of thyroid hormones. To minimize this interaction, administer thyroid hormones at least 4 hours before or after antacids or other drugs containing aluminum.
    Liothyronine: (Major) Aluminum hydroxide interferes with the intestinal absorption of thyroid hormones. To minimize this interaction, administer thyroid hormones at least 4 hours before or after antacids or other drugs containing aluminum.
    Loratadine; Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Mefenamic Acid: (Moderate) Ingestion of mefenamic acid with antacids is not recommended. Administration with an antacid containing 1.7 grams of magnesium hydroxide resulted in a 36 percent increase in the area under the time versus concentration curve of mefenamic acid.
    Mefloquine: (Moderate) Antacids, H2-blockers, and proton pump inhibitors (PPIs) may increase plasma concentrations of mefloquine. In a small study involving 6 healthy subjects and 6 peptic ulcer patients, cimetidine increased the Cmax and AUC of mefloquine. In the study, the pharmacokinetics of mefloquine were determined after receiving a single oral mefloquine 500 mg dose alone and after 3-days of cimetidine 400 mg PO bid. In both healthy subjects and peptic ulcer patients, Cmax was increased 42.4% and 20.5%, respectively. The AUC was increased by 37.5% in both groups. Elimination half-life, total clearance, and volume of distribution were not significantly affected. An increase in adverse reactions was not noted. Patients on chronic mefloquine therapy might be at increased risk of adverse reactions, especially in patients with a neurological or psychiatric history.
    Mesalamine, 5-ASA: (Major) Do not coadminister mesalamine extended-release capsules (Apriso) with antacids. Apriso is a pH-dependent, delayed-release product with an enteric coating that dissolves at a pH of at least 6. Theoretically, the delayed-release tablets, Lialda, may interact with drugs that raise the gastric pH. The delayed-release tablets have a gastroresistant film that covers the mesalamine tablet core; the film covering delays the initial release of the 5-ASA until the tablet is exposed to a pH of at least 7.
    Methenamine: (Major) The therapeutic action of methenamine requires an acidic urine. Antacids containing alkalinizing agents such as sodium bicarbonate can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
    Methenamine; Sodium Acid Phosphate: (Major) The therapeutic action of methenamine requires an acidic urine. Antacids containing alkalinizing agents such as sodium bicarbonate can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Major) The therapeutic action of methenamine requires an acidic urine. Antacids containing alkalinizing agents such as sodium bicarbonate can alkalinize the urine, thereby decreasing the effectiveness of methenamine by increasing the amount of non-ionized drug available for renal tubular reabsorption. Increased urine alkalinity also can inhibit the conversion of methenamine to formaldehyde, which is the active bacteriostatic form; concurrent use of methenamine and urinary alkalizers is not recommended.
    Methylphenidate: (Minor) The modified release characteristics of extended-release methylphenidate (Ritalin LA) are pH-dependent. Administration of antacids could alter the release of methylphenidate. Patients receiving extended-release methylphenidate with antacids should be monitored for adverse effects and/or reduced efficacy.
    Minocycline: (Moderate) Separate administration of minocycline and antacids by 2 to 3 hours. Coadministration may impair absorption of minocycline which may decrease its efficacy.
    Moxifloxacin: (Major) Administer oral moxifloxacin at least 4 hours before or 8 hours after products that contain aluminum hydroxide. Moxifloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids that contain aluminum hydroxide.
    Mycophenolate: (Major) Coadministration of mycophenolate mofetil with antacids decreases the bioavailability of mycophenolate mofetil. Aluminum/magnesium hydroxide antacids decrease the AUC of mycophenolic acid by about 17% when given as mycophenolate mofetil. Decreased absorption of mycophenolate (possible chelation) is the likely etiology for reduced systemic exposure. If antacids and mycophenolate need to be used together, separate administration times are recommended (do not give simultaneously).
    Naproxen: (Minor) Concomitant administration of antacids can delay the absorption of naproxen. Periodic antacid use should not be problematic as long as the antacid and enteric-coated naproxen administration are separated by at least 2 hours.
    Naproxen; Pseudoephedrine: (Minor) Concomitant administration of antacids can delay the absorption of naproxen. Periodic antacid use should not be problematic as long as the antacid and enteric-coated naproxen administration are separated by at least 2 hours. (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Naproxen; Sumatriptan: (Minor) Concomitant administration of antacids can delay the absorption of naproxen. Periodic antacid use should not be problematic as long as the antacid and enteric-coated naproxen administration are separated by at least 2 hours.
    Neratinib: (Major) Administer neratinib at least 3 hours after administration of antacids if concomitant use is necessary due to decreased absorption and systemic exposure of neratinib; the solubility of neratinib decreases with increasing pH of the GI tract. The efficacy of neratinib may be decreased.
    Nilotinib: (Moderate) If concomitant use of these agents is necessary, administer the antacid approximately 2 hours before or approximately 2 hours after the nilotinib dose. Nilotinib displays pH-dependent solubility with decreased solubility at a higher pH; therefore, concomitant use of nilotinib and antacids may result in decreased bioavailability of nilotinib. In a study in healthy subjects, there was no significant change in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered approximately 2 hours before or approximately 2 hours after a single 400-mg nilotinib dose.
    Nitrofurantoin: (Major) Antacids can delay both the rate and the extent of GI absorption of nitrofurantoin. This interaction may be due to surface absorption of the antibacterial onto the antacid. Separate administration by at least 1 hour.
    Norfloxacin: (Major) Administer products that contain aluminum hydroxide at least 2 hours before or 2 hours after norfloxacin. Norfloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids that contain aluminum hydroxide.
    Ofloxacin: (Major) Administer products that contain aluminum hydroxide at least 2 hours before or 2 hours after ofloxacin. Ofloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids that contain aluminum hydroxide.
    Omadacycline: (Moderate) Separate administration of omadacycline and antacids by 4 hours. Coadministration may impair absorption of omadacycline which may decrease its efficacy.
    Pancrelipase: (Major) The effectiveness of gastrointestinal enzymes can be diminished with concurrent administration of antacids. In-vitro studies suggest that calcium and magnesum cations exert their deleterious effect on replacement enzyme therapy by formation of poorly soluble calcium or magnesium soaps and precipitation of glycine conjugated bile salts.
    Pazopanib: (Moderate) Pazopanib displays pH-dependent solubility with decreased solubility at a higher pH. The concomitant use of pazopanib and antacids that elevate the gastric pH may reduce the bioavailability of pazopanib. If coadministration of pazopanib and a short-acting antacid is necessary, separate the dosing by several hours.
    Penicillamine: (Moderate) Because penicillamine chelates heavy metals, it is possible that antacids could reduce penicillamine bioavailability, which can decrease the therapeutic effects of penicillamine. Simultaneous administration should be avoided; separate dosing by at least 2 hours to limit an interaction.
    Phenytoin: (Moderate) Because the absorption of phenytoin suspension can be reduced by antacids containing magnesium, aluminum, or calcium, administration at the same time of day should be avoided when possible. Ingestion times of phenytoin capsules and calcium antacids should be staggered in patients with low serum phenytoin levels to prevent absorption difficulties. Studies evaluating the effects of magnesium-aluminium antacids on the absorption of phenytoin capsules or tablets have yielded conflicting results. Nevertheless, serum phenytoin levels and clinical response should be closely monitored if these agents are co-administered. The mechanisms by which antacids reduce phenytoin absorption may involve increased gastric transit time, chelation, adsorption, and/or altered solubility. The oral absorption of phenytoin may be reduced by calcium carbonate (e.g., as found in antacids) or other calcium salts. Calcium products may form complexes with phenytoin that are nonabsorbable. Although the magnitude of the interaction is not great, an occasional patient may be affected and the interaction may lead to subtherapeutic phenytoin concentrations. Separating the administration of phenytoin and antacids or calcium salts by at least 2 hours will help minimize the possibility of interaction.
    Phosphorus: (Moderate) The oral absorption of phosphorus is reduced by ingestion of aluminum-containing antacids (e.g., aluminum hydroxide). If the patient requires treatment with aluminum-containing antacids, it may be wise to separate the administration of phosphorus salts from the antacid. In some instances the administration of an aluminum hydroxide product is used therapeutically (e.g., uremia) to decrease serum phosphorus levels, so the administration of phosphorus supplements would dynamically counteract the intended use of these drugs in these settings, assuming hypophosphatemia is not present.
    Polyethylene Glycol; Electrolytes; Bisacodyl: (Minor) The concomitant use of bisacodyl tablets with antacids can cause the enteric coating of the bisacody tablet to dissolve prematurely, leading to possible gastric irritation or dyspepsia. Avoid antacids within 1 hour before or after the bisacodyl dosage.
    Polysaccharide-Iron Complex: (Major) Antacids may decrease the absorption of oral iron preparations. At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Ponatinib: (Major) Ponatinib displays pH-dependent aqueous solubility; therefore, concomitant use of ponatinib and antacids may result in decreased bioavailability and plasma exposure of ponatinib. Avoid concomitant use of ponatinib with antacids unless the benefit outweighs the possible risk of ponatinib underexposure. If the use of both agents is necessary, monitor patients for signs of reduced efficacy.
    Potassium Bicarbonate: (Major) Avoid coadministration of aluminum hydroxide with citrate salts due to the potential for increased absorption of aluminum. Patients at increased risk of aluminum accumulation include patients with renal impairment or renal failure.
    Potassium Chloride: (Major) Avoid coadministration of aluminum hydroxide with citrate salts due to the potential for increased absorption of aluminum. Patients at increased risk of aluminum accumulation include patients with renal impairment or renal failure.
    Potassium Citrate: (Severe) Avoid coadministration of antacids with citrate salts since increased absorption of aluminum can occur. In addition, some antacids like calcium carbonate, share the potential with the citrate salts for development of metabolic alkalosis, when given in higher dosage. (Major) Avoid coadministration of aluminum hydroxide with citrate salts due to the potential for increased absorption of aluminum. Patients at increased risk of aluminum accumulation include patients with renal impairment or renal failure.
    Propranolol: (Major) Antacids may reduce the absorption of propranolol. The need to stagger doses of propranolol has not been established, but may be prudent. Monitor clinical response, and adjust propranolol dosage if needed to attain therapeutic goals.
    Pseudoephedrine: (Minor) It appears that antacids containing aluminum hydroxide may increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If aluminum-based antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Quinidine: (Major) Alkalinizing agents such as antacids can increase renal tubular reabsorption of quinidine by alkalinizing the urine; higher quinidine serum concentrations and quinidine toxicity are possible.
    Quinine: (Major) Antacids may delay or decrease the absorption of quinine.
    Raltegravir: (Major) Coadministration or staggered administration of aluminum and/or magnesium-containing antacids is not recommended during treatment with raltegravir. Coadministration may result in decreased plasma concentrations of raltegravir, which may lead to HIV treatment failure or the development of viral resistance. In a drug interaction study, the AUC for raltegravir was decreased by 49% (90% CI, 35% to 60%), 51% (90% CI, 33% to 65%), and 30% (90% CI, 4% to 50%), when administered with, 2 hours before, and 2 hours after aluminum/magnesium hydroxide antacids, respectively.
    Rifampin: (Moderate) Concomitant use of antacids and rifampin may decrease the absorption of rifampin. Daily doses of rifampin should be given at least 1 hour before the ingestion of antacids.
    Rilpivirine: (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Riociguat: (Major) Separate administration of riociguat from antacids by at least 1 hour. Antacids such as aluminum hydroxide/magnesium hydroxide decrease riociguat absorption.
    Rosuvastatin: (Major) Coadministration of rosuvastatin with antacids has reduced rosuvastatin plasma concentrations by 54%. When the antacid is given 2 hours after rosuvastatin, no significant change in rosuvastatin plasma concentrations is observed.
    S-adenosyl-L-methionine, SAM-e: (Minor) Antacids are known to interfere with the absorption of many agents and could theoretically interfere with the oral absorption of SAM-e. It may be prudent for patients to separate the administration of antacids and SAM-e products.
    Sarecycline: (Major) Separate administration of sarecycline and antacids by 2 to 3 hours. Coadministration may impair absorption of sarecycline which may decrease its efficacy.
    Sodium Ferric Gluconate Complex; ferric pyrophosphate citrate: (Major) Antacids may decrease the absorption of oral iron preparations. At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Sodium Fluoride: (Moderate) Absorption of sodium fluoride may be reduced by concomitant use of antacids that contain aluminum. An interval of at least 2 hours is advisable between administration of sodium fluoride and aluminum hydroxide.
    Sodium Polystyrene Sulfonate: (Major) Simultaneous oral administration of cation-donating antacids or laxatives may reduce the potassium exchange capability of sodium polystyrene sulfonate. Examples of cation-donating antacids and laxatives include aluminum hydroxide, calcium carbonate, magnesium carbonate, magnesium citrate, and magnesium hydroxide. Patients who received concomitant oral sodium polystyrene sulfonate and non-absorbable cation-donating antacids and laxatives have developed systemic alkalosis. Intestinal obstruction due to concretions of aluminum hydroxide when used in combination with sodium polystyrene sulfonate has also been reported. One case of grand mal seizure has been reported in a patient with chronic hypocalcemia of renal failure who was given sodium polystyrene with magnesium hydroxide as laxative. Normally, antacids like magnesium hydroxide and calcium carbonate neutralize hydrochloric acid in the stomach, forming magnesium chloride and calcium chloride. As these compounds enter the small intestine, they react with bicarbonate, forming magnesium carbonate and calcium carbonate, which are insoluble. If polystyrene is administered, it blocks this reaction by binding to the magnesium and calcium ions before they can react with the bicarbonate. More hydrogen ions are lost from the stomach than are lost from the intestine, resulting in metabolic alkalosis. Rectal administration of sodium polystyrene sulfonate may reduce the severity of these interactions.
    Sofosbuvir; Velpatasvir: (Moderate) Separate the use of antacids and velpatasvir administration by 4 hours. Velpatasvir solubility decreases as pH increases; therefore, drugs that increase gastric pH are expected to decrease the concentrations of velpatasvir, potentially resulting in loss of antiviral efficacy.
    Sofosbuvir; Velpatasvir; Voxilaprevir: (Moderate) Separate the use of antacids and velpatasvir administration by 4 hours. Velpatasvir solubility decreases as pH increases; therefore, drugs that increase gastric pH are expected to decrease the concentrations of velpatasvir, potentially resulting in loss of antiviral efficacy.
    Sotalol: (Major) Coadministration of antacids with sotalol reduces the Cmax and AUC of sotalol by 26% and 20%, respectively. This interaction results in a 25% reduction in the bradycardic effect of sotalol (measured at rest). Antacid administration two hours after the sotalol dose does not alter sotalol pharmacokinetics or pharmacodynamics. Instruct patients to avoid using antacids containing aluminum hydroxide or magnesium hydroxide within 2 hours of taking sotalol.
    Sucralfate: (Major) Antacids can interfere with the binding capacity of sucralfate to the GI mucosa, decreasing its effectiveness. Antacids should not be administered within 30 minutes of sucralfate. In addition, antacids or other aluminum-containing agents should be used cautiously with sucralfate in patients with chronic renal failure due to the aluminum content of sucralfate and the potential for aluminum toxicity.
    Tacrolimus: (Major) Monitor tacrolimus whole blood trough concentration and reduce tacrolimus dose if needed during concurrent use of antacids. Magnesium and aluminum hydroxide antacids may increase the blood concentration of tacrolimus. In a single-dose crossover study in healthy volunteers, coadministration of tacrolimus and magnesium-aluminum-hydroxide resulted in a mean AUC increase of 21% and a 10% decrease in the mean tacrolimus Cmax, compared to tacrolimus administration alone.
    Tetracycline: (Moderate) Separate administration of tetracycline and antacids by 2 to 3 hours. Coadministration may impair absorption of tetracycline which may decrease its efficacy.
    Thyroid hormones: (Major) Aluminum hydroxide interferes with the intestinal absorption of thyroid hormones. To minimize this interaction, administer thyroid hormones at least 4 hours before or after antacids or other drugs containing aluminum.
    Ticlopidine: (Major) Administration of ticlopidine after antacids resulted in an 18% decrease in plasma levels of ticlopidine. Staggering the times of administration may avoid this pharmacokinetic interaction.
    Tipranavir: (Moderate) Concurrent administration of tipranavir and ritonavir with antacids results in decreased tipranavir concentrations. Administer tipranavir and ritonavir 2 hours before or 1 hour after antacids.
    Trospium: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Ursodeoxycholic Acid, Ursodiol: (Moderate) Aluminum hydroxide based antacids have been shown to adsorb bile acids in vitro and are expected to interfere with the efficacy of ursodeoxycholic acid, ursodiol. To minimize drug interactions, administer ursodiol at least 1 hour before or at least 2 hours after the aluminum-based antacid.
    Valproic Acid, Divalproex Sodium: (Minor) Antacids containing the combination of magnesium and aluminum hydroxide have been shown to increase valproic acid AUC by an average of 12%. Although this finding is of marginal clinical significance, patients should be monitored for adverse effects in this situation while taking valproic acid and aluminum hydroxide.
    Vitamin D analogs: (Moderate) The chronic use of aluminum-containing antacids for hyperphosphatemia in conjunction with vitamin D analogs can lead to increased aluminum concentrations and toxicity. This is of primary significance in patients with chronic renal failure. Aluminum hydroxide may be used as a phosphate binder in patients receiving vitamin D analogs. The serum phosphate, calcium and calculated calcium-phosphate product (serum Ca x PO4) should be monitored closely. After initiating vitamin D analog therapy, the dose of phosphate binders should be decreased to correct persistent mild hypercalcemia or increased to correct persistent mild hyperphosphatemia.
    Vitamin D: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Zalcitabine, ddC: (Moderate) The absorption of zalcitabine is moderately reduced when coadministered with aluminum hydroxide. As the clinical significance of this interaction is not known, the simultaneous administration of zalcitabine and aluminum is not recommended.

    PREGNANCY AND LACTATION

    Pregnancy

    A specific FDA pregnancy risk category has not been assigned to aluminum hydroxide. When chronic use and high doses are avoided, aluminum hydroxide appears to be safe and effective for the occasional relief of dyspepsia and pyrosis in the mother during pregnancy. When used occasionally at recommended doses, aluminum containing antacids have not been found to produce teratogenic effects and are generally considered safe during pregnancy, provided the pregnant woman does not have concerns with renal dysfunction. Increased tendon reflexes have been reported in newborns whose mothers were using aluminum containing antacid products chronically and in high doses during their pregnancy. It may be advisable to consider a combination antacid rather than aluminum hydroxide alone for relief of dyspepsia or pyrosis during pregnancy as the combination antacids allow for comparative relief of symptoms at lower doses.

    When chronic use and high doses are avoided, aluminum hydroxide appears to be safe and effective for the occasional relief of dyspepsia and pyrosis in the mother during breast-feeding. Aluminum does not enter breast milk significantly, and no problems have been reported during breast-feeding. It may be advisable to consider a combination antacid rather than aluminum hydroxide alone for relief of dyspepsia or pyrosis while breast-feeding, as the combination antacids allow for comparative relief of symptoms at lower doses.

    MECHANISM OF ACTION

    Following oral administration, aluminum hydroxide is slowly solubilized in the stomach and reacts with hydrochloric acid to produce aluminum chloride and water. This chemical reaction neutralizes gastric acid secretions and increases the gastric pH. The increase in gastric pH inhibits the proteolytic action of pepsin, an effect that is particularly important in patients with peptic ulcer disease. The increased pH and decreased pepsin production helps in the healing of peptic ulcers. While gastric acids are neutralized, the actual secretion of acid is not effected. The chloride salt of aluminum produced in the stomach reacts with bicarbonate in the small intestine to minimize the risk of systemic alkalosis. Compared with magnesium hydroxide, aluminum hydroxide reacts slowly with bicarbonate because it dissolves slowly in the stomach, which adds to its longer duration of action. In the management of esophageal reflux, the increase in gastric pH produced by antacids, including aluminum hydroxide, causes an increase in the lower esophageal sphincter pressure. This increased pressure minimizes the amount of reflux to the esophagus.
     
    Aluminum hydroxide complexes with dietary phosphate to form the insoluble aluminum phosphate, which is excreted in the feces. This reduces the amount of phosphate that is available for absorption. For aluminum hydroxide to be beneficial in preventing phosphate absorption, it must be administered with meals or snacks. This hypophosphatemic effect of aluminum hydroxide has been used in the management of hyperphosphatemia associated with chronic renal insufficiency, hyperparathyroidism secondary to chronic hemodialysis, and calcinosis universalis; however, calcium carbonate is the preferred treatment for these conditions. Decreased phosphate absorption causes an increase in calcium absorption.

    PHARMACOKINETICS

    Aluminum hydroxide is administered orally. Aluminum hydroxide is slowly solubilized in the stomach and reacts with hydrochloric acid in the stomach to produce aluminum chloride and water. About 17—30% of the aluminum chloride is absorbed and is rapidly excreted by the kidneys in patients with normal renal function. In the small intestine, aluminum chloride is rapidly converted to insoluble, poorly absorbed basic aluminum salts. Aluminum also combines with dietary phosphate in the intestine forming insoluble, nonabsorbable aluminum phosphate which is excreted in the feces. The aluminum that is not absorbed remains in the GI tract and is excreted in the feces.