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  • CLASSES

    Serotonin Norepinephrine Reuptake Inhibitor Antidepressants, SNRIs

    BOXED WARNING

    Children, suicidal ideation

    Safety and effectiveness of desvenlafaxine in children and adolescents younger than 18 years of age have not been established. In October 2004, the FDA directed manufacturers of all antidepressants to include a boxed warning detailing the risk of suicide in pediatric patients. A causal role has been established for antidepressants in inducing suicidality in pediatric patients. The risk of suicidality for these drugs was identified in a pooled analysis of 24 placebo-controlled trials (n = 4,400) lasting up to 16 weeks in pediatric patients with major depressive disorder (MDD), obsessive compulsive disorder (OCD), or other psychiatric disorders. The analysis showed a greater risk of suicidality during the first few months of treatment in those receiving antidepressants (SSRIs and others). The average risk of such events on drug was 4% and 2% for placebo; however, no suicides occurred in these trials. Pooled analysis of short-term clinical trials during early phase treatment with SSRIs and other antidepressants in young adults (18 to 24 years) also showed an increased risk of suicidal thinking and behavior. The need for an antidepressant in pediatric patients or young adults for any use must be weighed against the risk of increased suicidality; patients who are started on therapy should be observed closely for clinical worsening, suicidality, or unusual changes in behavior, particularly within the first few months of starting therapy or at the time of dose increase or decrease; such observation would generally include at least weekly face-to-face contact with patients during the first 4 weeks of treatment, then every other week visits for the next 4 weeks, then at 12 weeks, and as clinically indicated beyond 12 weeks; additional contact by telephone may be appropriate between visits. It is unknown if the suicidality risk in children and young adults extends to longer-term therapy (i.e., beyond several months). The possibility of a suicide attempt is inherent in patients with depressive symptoms, whether these occur in primary depression or in association with another primary disorder such as OCD. All patients with a history of suicidal ideation or behaviors and those with a prominence of suicidal ideation prior to treatment are considered at an increased risk for suicidal ideation or attempts, and should be closely monitored during treatment with desvenlafaxine. In patients who exhibit changes in symptoms, worsening of depression or emergent suicidality, a decision should be made to change or discontinue treatment. If discontinuing, the medication should be tapered as rapidly as possible, but with recognition that abrupt discontinuation can also cause adverse symptoms. All antidepressants should be prescribed in the smallest quantity consistent with good patient management in order to reduce the risk of overdose.

    DEA CLASS

    Rx

    DESCRIPTION

    Oral serotonin-norepinephrine reuptake inhibitor (SNRI); salt form of an active metabolite of venlafaxine.
    Approved for major depressive disorder in adults; used off-label for vasomotor symptoms associated with menopause.
    Under investigation as a potential treatment for pain associated with peripheral diabetic neuropathy and fibromyalgia syndrome.

    COMMON BRAND NAMES

    Khedezla, Pristiq

    HOW SUPPLIED

    Desvenlafaxine/Desvenlafaxine Succinate/Khedezla/Pristiq Oral Tab ER: 25mg, 50mg, 100mg

    DOSAGE & INDICATIONS

    For the treatment of major depression.
    Oral dosage (extended-release tablets)
    Adults

    Initially, 50 mg PO once daily. Doses of 50 to 400 mg/day have been studied, although additional benefit has not been observed with doses above 50 mg/day. Reduced doses may be advisable in geriatric patients due to decreased clearance; every other day dosing may be considered in geriatric patients with poor tolerability to the drug. Adverse effects and discontinuation rates have been more frequent with higher doses. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Max: 400 mg/day PO. DISCONTINUATION: Whenever possible, a gradual taper is recommended. A taper over at least 2 to 3 weeks has been recommended. Discontinuation symptoms have been reported with doses ranging from 50 to 400 mg/day and tapering schedules for dosages of 100 to 400 mg/day over 1 to 2 weeks. Although a specific tapering schedule for the 50 mg/day dose is not available, a taper to 50 mg every other day for 1 to 2 weeks with adjustments as needed may be advisable.

    For the treatment of vasomotor symptoms (e.g., hot flashes†) associated with menopause†.
    Oral dosage (extended-release tablets)
    Adult menopausal females

    Initially, 50 mg PO once daily. Titrate up to 100 to 150 mg/day PO if clinically indicated. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. In a fixed-dose study comparing 50 mg/day, 100 mg/day, 150 mg/day, and 200 mg/day, the only dose that separated from placebo in efficacy endpoints was 100 mg/day PO. In one large, 12-week controlled trial (n = 365), 64% of patients in the desvenlafaxine group (100 mg/day) had a reduction of 5.35 moderate-to-severe hot flashes per day compared with only 41% of women in the placebo group. During the maintenance phase, reductions in the desvenlafaxine group were larger than the placebo group in month 6 (reduction by 73.3% vs. 53.9%) and month 12 (reduction by 65.8% vs. 41.4%) in moderate and severe hot flashes per day. Common side effects of desvenlafaxine were nausea, dry mouth, and constipation. Hormone therapy is considered the most effective treatment for vasomotor symptoms associated with menopause; however, per the American College of Obstetricians and Gynecologists (ACOG) and the North American Menopause Society (NAMS) Guidelines for non-hormonal therapy, desvenlafaxine is one of the effective alternatives for women who cannot use, or do not wish to use, hormonal therapy for vasomotor symptom control.

    †Indicates off-label use

    MAXIMUM DOSAGE

    Adults

    400 mg/day PO.

    Elderly

    400 mg/day PO.

    Adolescents

    Safe and effective use has not been established.

    Children

    Safe and effective use has not been established.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Mild hepatic impairment (Child-Pugh A): Dosage adjustment is not needed.
    Moderate to severe hepatic impairment (Child-Pugh B and C): The recommended dose is 50 mg/day PO; dose escalation above 100 mg/day PO is not recommended.

    Renal Impairment

    CrCl 50 to 80 mL/minute: No dosage adjustment needed.
    CrCl 30 to 50 mL/minute: 50 mg every day is the recommended daily and maximum dosage.
    CrCl less than 30 mL/minute: 50 mg every other day is the recommended daily and maximum dosage.
    End-stage renal disease (ESRD): 50 mg every other day is the recommended daily and maximum dosage.

    ADMINISTRATION

     
    •A Med Guide is available that describes the risks, benefits and appropriate use of therapy and this guide should be dispensed to patients during receipt of the drug.

    Oral Administration

    •May administer with or without food. Administration with food may minimize gastrointestinal side effects.

    Oral Solid Formulations

    •Extended-release tablets: Do not divide, cut, chew, or crush.

    STORAGE

    Generic:
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    Khedezla:
    - Avoid excessive humidity
    - Protect from moisture
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    Pristiq:
    - Store at controlled room temperature (between 68 and 77 degrees F)

    CONTRAINDICATIONS / PRECAUTIONS

    General Information

    Some reports suggest that a false positive urine drug screen may occur for amphetamine or phencyclidine in patients who have received desvenlafaxine. Caution should be exercised when interpreting positive urine drug screens for these medications, and confirmation by alternative tests such as gas chromatography/mass spectrometry should be considered.

    Desvenlafaxine hypersensitivity, venlafaxine hypersensitivity

    Desvenlafaxine should not be given to any patient with a known desvenlafaxine hypersensitivity or venlafaxine hypersensitivity, or a reaction to any other ingredient in the formulation. Cross-sensitivity is possible in those with a previous history of venlafaxine hypersensitivity, since venlafaxine is the parent compound of desvenlafaxine. Angioedema has been reported with desvenlafaxine use.

    Abrupt discontinuation

    In general, abrupt discontinuation of antidepressants should be avoided. Individualized tapering of desvenlafaxine may be necessary. Gradual tapering is recommended during discontinuation of any serotonin-norepinephrine reuptake inhibitor (SNRI) drug to decrease or prevent the occurrence of potential withdrawal symptoms. Withdrawal symptoms have been reported with abrupt discontinuation or tapering of desvenlafaxine and have included abnormal dreams, headache, insomnia, dizziness, nausea/vomiting, paresthesia, irritability, fatigue, diarrhea, anxiety, vertigo, hyperhidrosis, and a small increase in recumbent heart rate. More severe symptoms such as confusion, hypomanic episode, and seizures have been reported following discontinuation of other SNRIs and similar medications. Patients should be carefully monitored if abrupt discontinuation of the SNRI becomes necessary. If the decision has been made to discontinue treatment more emergently, medication should be tapered, as rapidly as is feasible, but with recognition that abrupt discontinuation can be associated with certain symptoms.

    Bipolar disorder, mania

    During all clinical studies for major depression, mania was reported for approximately 0.02% of patients treated with desvenlafaxine. Activation of mania/hypomania has also been reported in a small proportion of patients with major affective disorder who were treated with other marketed antidepressants. As with all antidepressants, desvenlafaxine should be used cautiously in patients with a history or family history of mania or hypomania. A major depressive episode may be the initial presentation of bipolar disorder. Patients with depressive symptoms should be adequately screened to determine if they are at risk for bipolar disorder prior to initiating treatment. Such screening should include a detailed psychiatric history, including a family history of suicide, bipolar disorder, and depression. It is advisable to closely monitor the response of patients with a previously established history of bipolar disorder if therapy with an antidepressant is indicated.

    Children, suicidal ideation

    Safety and effectiveness of desvenlafaxine in children and adolescents younger than 18 years of age have not been established. In October 2004, the FDA directed manufacturers of all antidepressants to include a boxed warning detailing the risk of suicide in pediatric patients. A causal role has been established for antidepressants in inducing suicidality in pediatric patients. The risk of suicidality for these drugs was identified in a pooled analysis of 24 placebo-controlled trials (n = 4,400) lasting up to 16 weeks in pediatric patients with major depressive disorder (MDD), obsessive compulsive disorder (OCD), or other psychiatric disorders. The analysis showed a greater risk of suicidality during the first few months of treatment in those receiving antidepressants (SSRIs and others). The average risk of such events on drug was 4% and 2% for placebo; however, no suicides occurred in these trials. Pooled analysis of short-term clinical trials during early phase treatment with SSRIs and other antidepressants in young adults (18 to 24 years) also showed an increased risk of suicidal thinking and behavior. The need for an antidepressant in pediatric patients or young adults for any use must be weighed against the risk of increased suicidality; patients who are started on therapy should be observed closely for clinical worsening, suicidality, or unusual changes in behavior, particularly within the first few months of starting therapy or at the time of dose increase or decrease; such observation would generally include at least weekly face-to-face contact with patients during the first 4 weeks of treatment, then every other week visits for the next 4 weeks, then at 12 weeks, and as clinically indicated beyond 12 weeks; additional contact by telephone may be appropriate between visits. It is unknown if the suicidality risk in children and young adults extends to longer-term therapy (i.e., beyond several months). The possibility of a suicide attempt is inherent in patients with depressive symptoms, whether these occur in primary depression or in association with another primary disorder such as OCD. All patients with a history of suicidal ideation or behaviors and those with a prominence of suicidal ideation prior to treatment are considered at an increased risk for suicidal ideation or attempts, and should be closely monitored during treatment with desvenlafaxine. In patients who exhibit changes in symptoms, worsening of depression or emergent suicidality, a decision should be made to change or discontinue treatment. If discontinuing, the medication should be tapered as rapidly as possible, but with recognition that abrupt discontinuation can also cause adverse symptoms. All antidepressants should be prescribed in the smallest quantity consistent with good patient management in order to reduce the risk of overdose.

    MAOI therapy

    Desvenlafaxine is contraindicated for concomitant use in patients receiving MAOI therapy, due to the risk for serotonin syndrome. Desvenlafaxine is a serotonin norepinephrine reuptake inhibitor (SNRI) and should not be used concurrently with MAOI therapy or within 14 days of discontinuation of a MAOI intended to treat a psychiatric disorder. Similarly, treatment with such MAOIs should not be initiated for at least 7 days after stopping desvenlafaxine. In addition, do not start desvenlafaxine in a patient who is being treated with linezolid or intravenous methylene blue. Serotonin syndrome has been reported with SNRIs, including desvenlafaxine, both when taken alone, but especially when coadministered with other serotonergic agents (including other SNRIs, triptans, selective serotonin reuptake inhibitors or SSRIs, tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines, and St. John’s Wort). If such symptoms occur, discontinue desvenlafaxine and initiate supportive treatment. Do not give desvenlafaxine with other SNRI treatments. If concomitant use of desvenlafaxine with other serotonergic drugs is clinically warranted, patients should be made aware of a potential increased risk for serotonin syndrome, particularly during treatment initiation and dose increases.

    Electroconvulsive therapy (ECT), seizure disorder

    Cases of seizure have been reported in premarketing clinical studies with desvenlafaxine. Desvenlafaxine has not been systematically evaluated in patients with a seizure disorder. Patients with a history of seizures were excluded from premarketing clinical studies; prescribe with caution in patients with a seizure disorder. Desvenlafaxine's effects during electroconvulsive therapy (ECT) have not been evaluated in clinical studies.

    Dehydration, hyponatremia, hypovolemia

    Serotonin norepinephrine reuptake inhibitors (SNRIs), like desvenlafaxine, may cause hyponatremia, which is frequently the result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). In some cases, serum sodium levels less than 110 mmol/L have been reported; however, the adverse effect appeared reversible upon discontinuation of the causative SNRI. Older patients, those receiving diuretics or prone to dehydration, and those who are otherwise volume depleted (e.g., hypovolemia) appear to be at greatest risk. Hyponatremia may manifest as headache, difficulty concentrating, memory impairment, confusion, weakness, and unsteadiness which may result in falls. Severe manifestations include hallucinations, syncope, seizure, coma, respiratory arrest, and death. Symptomatic hyponatremia may require discontinuation of the SNRI, as well as implementation of the appropriate medical interventions.

    Cardiac disease, cerebrovascular disease, hypertension

    Patients receiving dexvenlafaxine should have regular monitoring of blood pressure since increases in blood pressure were observed in clinical studies. Pre-existing hypertension should be controlled before initiating treatment. Caution should be exercised in treating patients with pre-existing hypertension, cardiac disease, or cerebrovascular disease, or other conditions that might be compromised by increases in blood pressure. Cases of elevated blood pressure requiring immediate treatment have been reported with desvenlafaxine. Sustained blood pressure increases could have adverse consequences. For patients who experience a sustained increase in blood pressure while receiving desvenlafaxine, either dose reduction or discontinuation should be considered.

    Hepatic disease

    Caution is advised when prescribing desvenlafaxine in patients with hepatic disease. Patients with moderate to severe hepatic impairment have reduced drug clearance and increased exposure compared to healthy patients. The usual dose may be used in patients with mild hepatic impairment, with careful monitoring. Dosage reduction is recommended in patients with moderate to severe hepatic impairment (Child-Pugh Class B and C), and the recommended maximum dosage should not be exceeded.

    Renal failure, renal impairment

    Caution is advised when prescribing desvenlafaxine in patients with renal impairment or renal failure, due to increased drug exposure. The half-life of desvenlafaxine is significantly prolonged in patients with renal dysfunction. Dosage reductions are recommended for those with moderate to severe renal impairment (CrCl 50 mL/minute or less) and end-stage renal disease. Do not exceed recommended maximum dosages in these patients.

    Anticoagulant therapy, bleeding, thrombolytic therapy

    Monitor patients taking an desvenlafaxine for signs and symptoms of bleeding. Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs), like desvenlafaxine, due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage). Concurrent use of aspirin, NSAIDs, anticoagulant therapy, thrombolytic therapy, or other medications that enhance bleeding potential may increase this risk. Patients taking desvenlafaxine should be instructed to promptly report any bleeding events to the practitioner.

    Closed-angle glaucoma, increased intraocular pressure

    Caution is recommended when prescribing desvenlafaxine to patients with closed-angle glaucoma. The pupillary dilation that can occur with antidepressants may precipitate a closed-angle glaucoma attack in patients with anatomically narrow angles who do not have a patent iridectomy. An acute attack of closed-angle glaucoma is considered a medical emergency because the increased intraocular pressure is rapid and severe, and may quickly result in blindness if left untreated.

    Eosinophilic pneumonia

    Interstitial lung disease and eosinophilic pneumonia associated with venlafaxine (the parent drug of desvenlafaxine) therapy have been rarely reported. The possibility of these adverse events should be considered in patients treated with desvenlafaxine who present with progressive dyspnea, cough, or chest discomfort. Such patients should undergo a prompt medical evaluation, and discontinuation of desvenlafaxine should be considered.

    Driving or operating machinery, ethanol ingestion

    A clinical study has shown that desvenlafaxine does not increase the impairment of mental and motor skills caused by ethanol. However, as with all central nervous system (CNS)-active drugs, patients should be advised to avoid ethanol ingestion while taking desvenlafaxine. Consistent with other drugs that act on the CNS, patients taking desvenlafaxine should use caution when driving or operating machinery until the full effects of the drug are known.

    Neonates, pregnancy

    There are no adequate and well-controlled studies regarding use of desvenlafaxine during human pregnancy. Desvenlafaxine should be used in pregnancy only where the benefit to the mother clearly outweighs any potential risk to the fetus. In reproductive developmental studies in rats and rabbits with desvenlafaxine, there was no evidence of teratogenicity at doses up to 30 times a human dose of 100 mg/day (on a mg/m2 basis) in rats, and up to 15 times a human dose of 100 mg/day (on a mg/m2 basis) in rabbits. An increase in rat pup deaths was seen during the first 4 days of lactation when dosing occurred during gestation and lactation, at doses greater than 10 times a human dose of 100 mg/day (on a mg/m2 basis). Non-teratogenic effects have been reported in humans. If the clinician and patient decide to continue desvenlafaxine during pregnancy, discontinuation symptoms should be considered in the newborn at birth. Neonates exposed to serotonergic antidepressants late in the third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding. Such complications can arise immediately upon delivery. Features are consistent with either a direct toxic effect of serotonergic agents or, possibly, a neonatal abstinence syndrome. It should be noted that, in some cases, the clinical picture is consistent with serotonin syndrome. When treating a pregnant woman with an SNRI or other serotonergic agent during the third trimester, the physician should carefully consider the potential risks and benefits of treatment. If clinically feasible, gradual tapering of the medication prior to delivery may be considered. The effects of desvenlafaxine on labor and delivery are unknown.

    Breast-feeding

    Desvenlafaxine is excreted in human breast milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue breast-feeding or to discontinue desvenlafaxine. Data describing the clinical effects of infant exposure after maternal desvenlafaxine administration are not available. However, desvenlafaxine is the active metabolite of venlafaxine, and several small case series have described infants who were breast-fed by mothers taking venlafaxine. The majority of infants had measurable desvenlafaxine plasma concentrations. Consider if treatment alternatives are appropriate. Due to individual variability in response to antidepressants, it may be prudent to continue the existing regimen if ongoing treatment is deemed necessary during breast-feeding. However, because a pooled analysis found that maternal use of sertraline, along with nortriptyline and paroxetine, usually produced undetectable or low drug concentrations in infant serum, these agents may be the preferred antidepressants when initiating antidepressant therapy in a breast-feeding mother. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    Geriatric

    In clinical studies for desvenlafaxine pre-FDA approval, no overall differences in safety or efficacy were observed between geriatric and younger adult patients. However, in the short-term placebo-controlled studies, there was a higher incidence of systolic orthostatic hypotension in geriatric patients (65 years of age and older) compared to younger adults treated with desvenlafaxine. For older adults, possible reduced renal clearance of desvenlafaxine should be considered when determining an appropriate dose. Geriatric patients are also at greater risk for developing clinically significant hyponatremia, a complication that is considered to be a class effect of serotonin norepinephrine reuptake inhibitors (SNRIs). Symptomatic hyponatremia may require discontinuation of the SNRI, as well as implementation of the appropriate medical interventions. According to the Beers Criteria, SNRIs are considered potentially inappropriate medications (PIMs) in older adults and should be used cautiously because SNRIs can cause or exacerbate hyponatremia and SIADH and the elderly are at increased risk of developing these conditions. Sodium levels should be closely monitored when starting or changing dosages in older adults. The federal Omnibus Budget Reconciliation Act (OBRA) regulates the use of antidepressants in residents of long-term care facilities. According to OBRA, the duration of therapy should be in accordance with pertinent literature for the condition being treated, including clinical practice guidelines. All residents being treated for depression with any antidepressant should be monitored closely for worsening of depression and/or suicidal behavior or thinking, especially during initiation of therapy and during dose changes. Antidepressants may cause dizziness, nausea, diarrhea, anxiety, nervousness, insomnia, somnolence, weight gain, anorexia, or increased appetite. Many of these effects can increase the risk for falls. Prior to discontinuation, many antidepressants may need a taper to avoid a withdrawal syndrome. Concurrent use of 2 or more antidepressants may increase the risk of side effects; in such cases there should be documentation of expected benefits that outweigh the associated risks and monitoring for any increase in side effects. Monitoring should consist of a review for continued need at least quarterly, and documentation of the rationale for continuation. When the drug is being used to manage behavior, stabilize mood, or treat a psychiatric disorder, the facility should attempt to taper the medication as outlined in the OBRA guidelines, unless a taper is clinically contraindicated.

    ADVERSE REACTIONS

    Severe

    seizures / Delayed / 0-2.0
    angioedema / Rapid / 0-2.0
    pancreatitis / Delayed / Incidence not known
    suicidal ideation / Delayed / Incidence not known
    SIADH / Delayed / Incidence not known
    GI bleeding / Delayed / Incidence not known
    myocardial infarction / Delayed / Incidence not known
    Stevens-Johnson syndrome / Delayed / Incidence not known
    toxic epidermal necrolysis / Delayed / Incidence not known
    erythema multiforme / Delayed / Incidence not known
    eosinophilic pneumonia / Delayed / Incidence not known
    serotonin syndrome / Delayed / Incidence not known
    neonatal abstinence syndrome / Early / Incidence not known

    Moderate

    withdrawal / Early / 22.0-50.0
    constipation / Delayed / 9.0-14.0
    impotence (erectile dysfunction) / Delayed / 3.0-11.0
    hypercholesterolemia / Delayed / 0-10.0
    orthostatic hypotension / Delayed / 0-8.0
    proteinuria / Delayed / 5.0-8.0
    ejaculation dysfunction / Delayed / 0-7.0
    hypertriglyceridemia / Delayed / 1.0-6.0
    blurred vision / Early / 3.0-4.0
    hypertension / Early / 0.7-2.3
    dystonic reaction / Delayed / 0-2.0
    teeth grinding (bruxism) / Delayed / 0-2.0
    sinus tachycardia / Rapid / 0-2.0
    urinary retention / Early / 0-2.0
    hyperprolactinemia / Delayed / 0-2.0
    elevated hepatic enzymes / Delayed / 0-2.0
    peripheral vasodilation / Rapid / 1.0-2.0
    mania / Early / 0-0.1
    hallucinations / Early / Incidence not known
    hostility / Early / Incidence not known
    akathisia / Delayed / Incidence not known
    depression / Delayed / Incidence not known
    impulse control symptoms / Delayed / Incidence not known
    hyponatremia / Delayed / Incidence not known
    platelet dysfunction / Delayed / Incidence not known
    hematoma / Early / Incidence not known
    bleeding / Early / Incidence not known
    dyspnea / Early / Incidence not known

    Mild

    nausea / Early / 22.0-41.0
    xerostomia / Early / 11.0-25.0
    hyperhidrosis / Delayed / 10.0-21.0
    dizziness / Early / 10.0-16.0
    insomnia / Early / 9.0-15.0
    drowsiness / Early / 4.0-12.0
    fatigue / Early / 7.0-11.0
    anorexia / Delayed / 5.0-10.0
    vomiting / Early / 3.0-9.0
    tremor / Early / 2.0-9.0
    orgasm dysfunction / Delayed / 0-8.0
    libido decrease / Delayed / 3.0-6.0
    mydriasis / Early / 2.0-6.0
    vertigo / Early / 1.0-5.0
    anxiety / Delayed / 3.0-5.0
    abnormal dreams / Early / 2.0-4.0
    yawning / Early / 1.0-4.0
    chills / Rapid / 0-4.0
    weight gain / Delayed / 0-2.0
    dysgeusia / Early / 1.0-2.0
    syncope / Early / 0-2.0
    photosensitivity / Delayed / 0-2.0
    rash (unspecified) / Early / 0-2.0
    alopecia / Delayed / 0-2.0
    tinnitus / Delayed / 1.0-2.0
    flushing / Rapid / 1.0-2.0
    musculoskeletal pain / Early / 0-2.0
    asthenia / Delayed / 0-2.0
    weight loss / Delayed / Incidence not known
    irritability / Delayed / Incidence not known
    agitation / Early / Incidence not known
    ecchymosis / Delayed / Incidence not known
    epistaxis / Delayed / Incidence not known
    petechiae / Delayed / Incidence not known
    cough / Delayed / Incidence not known

    DRUG INTERACTIONS

    Abciximab: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) like desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving abciximab. Monitor the patient closely for signs and symptoms of bleeding.
    Acetaminophen; Aspirin, ASA; Caffeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Acetaminophen; Dextromethorphan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Acetaminophen; Dextromethorphan; Doxylamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Acetaminophen; Dextromethorphan; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Acetaminophen; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Acetaminophen; Pentazocine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Acetaminophen; Tramadol: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In one case, the addition of tramadol to extended-release venlafaxine (300 mg/day) and mirtazapine (30 mg/day) likely caused serotonin syndrome. A patient developed agitation, confusion, severe shivering, diaphoresis, myoclonus, hyperreflexia, mydriasis, tachycardia, and fever within 7 weeks of taking tramadol 400 mg daily. He had taken 300 mg tramadol without difficulty. Discontinuation of the 3 drugs and rehydration led to symptom resolution over 36 hours. Reinstitution of the antidepressants 3 days after patient presentation was uneventful. In addition, although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as tramadol, be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.
    Almotriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Alteplase, tPA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aminosalicylate sodium, Aminosalicylic acid: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Amitriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.
    Amitriptyline; Chlordiazepoxide: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.
    Amoxapine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have central serotonergic properties such as amoxapine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Amphetamine; Dextroamphetamine Salts: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as amphetamines. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 1 to 2 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving SNRIs and amphetamines should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Anagrelide: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Anticoagulants: (Major) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication in patients receiving anticoagulants. Elevations in prothrombin time, activated partial thromboplastin and INR values have been reported post-marketing when venlafaxine was added to established warfarin therapy. The causality and mechanism of this potential interaction have not been established. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with an anticoagulant medication and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Butalbital; Caffeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Carisoprodol: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Dipyridamole: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Omeprazole: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Oxycodone: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Aspirin, ASA; Pravastatin: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Atazanavir; Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with desvenlafaxine as there is a potential for elevated cobicistat concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Desvenlafaxine is an inhibitor of CYP2D6; cobicistat is partially metabolized by CYP2D6.
    Atomoxetine: (Major) Desvenlafaxine is a serotonin norepinephrine reuptake inhibitor (SNRI) and atomoxetine selectively inhibits norepinephrine reuptake; the drugs have some additive pharmacology that may lead to increases in blood pressure or heart rate. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer of desvenlafaxine recommends that the dose of primary substrates of CYP2D6, such as atomoxetine, be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day. Monitor for adverse effects, such as dizziness, drowsiness, nervousness, insomnia, and cardiac effects (e.g., hypertension, increased pulse rate, QT prolongation) during concurrent use.
    Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Benzphetamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as amphetamines. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 12 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving an SNRI and an amphetamine should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Bismuth Subsalicylate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Bismuth Subsalicylate; Metronidazole; Tetracycline: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Bromocriptine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as bromocriptine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Brompheniramine; Dextromethorphan; Guaifenesin: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Buprenorphine: (Major) Concurrent use of opioids with other drugs that modulate serotonergic function, such as SNRIs (e.g., desvenlafaxine, duloxetine, milnacipran, levomilnacipran, venlafaxine), has resulted in serotonin syndrome in some cases. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If combination treatment is required, patients should be carefully observed, particularly during treatment initiation and during dose adjustments of the serotonergic drug; discontinue buprenorphine if serotonin syndrome is suspected.
    Buprenorphine; Naloxone: (Major) Concurrent use of opioids with other drugs that modulate serotonergic function, such as SNRIs (e.g., desvenlafaxine, duloxetine, milnacipran, levomilnacipran, venlafaxine), has resulted in serotonin syndrome in some cases. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If combination treatment is required, patients should be carefully observed, particularly during treatment initiation and during dose adjustments of the serotonergic drug; discontinue buprenorphine if serotonin syndrome is suspected.
    Buspirone: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as buspirone. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Cabergoline: (Moderate) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties, such as cabergoline. Cabergoline has minimal affinity for serotonin receptors, possibly reducing the risk of this interaction compared to the chemically related ergot alkaloids. However, patients receiving cabergoline with an SNRI should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Celecoxib: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Chlorpheniramine; Dextromethorphan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Chlorpromazine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Choline Salicylate; Magnesium Salicylate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Cilostazol: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Citalopram: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms.
    Clomipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Clopidogrel: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with desvenlafaxine as there is a potential for elevated cobicistat concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Desvenlafaxine is an inhibitor of CYP2D6; cobicistat is partially metabolized by CYP2D6.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) Caution is warranted when cobicistat is administered with desvenlafaxine as there is a potential for elevated cobicistat concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Desvenlafaxine is an inhibitor of CYP2D6; cobicistat is partially metabolized by CYP2D6.
    Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Caution is warranted when cobicistat is administered with desvenlafaxine as there is a potential for elevated cobicistat concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Desvenlafaxine is an inhibitor of CYP2D6; cobicistat is partially metabolized by CYP2D6.
    Cyclobenzaprine: (Major) Cautious use of cyclobenzaprine and drugs that increase serotonin concentrations such as serotonin norepinephrine reuptake inhibitors (SNRIs) is advised because of the possibility of serotonin syndrome. If these drugs must be used together, closely monitor the patient for signs and symptoms of serotonin syndrome. If such a reaction develops, immediately discontinue cyclobenzaprine and the SSRI. A suspected case of serotonin syndrome was noted in a man who took duloxetine, opiates, and cyclobenzaprine. The man developed worsening confusion, hallucinations, diaphoresis, tachycardia, tremors, marked agitation, spontaneous sustained clonus, and multifocal myoclonus.but recovered after duloxetine and cyclobenzaprine discontinuation and cyproheptadine initiation. In addition, cyclobenzaprine is structurally similar to tricyclic antidepressants (TCAs) and like TCAs, is associated with a possible risk of QT prolongation and torsades de pointes (TdP), particularly in the event of acute overdose. Drugs with a possible risk for QT prolongation and TdP that should be used cautiously with cyclobenzaprine include venlafaxine and potentially other SNRIs.
    Darunavir; Cobicistat: (Moderate) Caution is warranted when cobicistat is administered with desvenlafaxine as there is a potential for elevated cobicistat concentrations. Clinical monitoring for adverse effects is recommended during coadministration. Desvenlafaxine is an inhibitor of CYP2D6; cobicistat is partially metabolized by CYP2D6.
    Desipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dexmethylphenidate: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as dexmethylphenidate and serotonin norepinephrine reuptake inhibitors (SNRIs). There are rare reports of serotonin syndrome occurring during use of other serotonergic antidepressants (i.e., SSRIs) and methylphenidate, a racemic compound containing dexmethylphenidate. There is also a case of a neuroleptic malignant syndrome-like reaction occurring in a child on chronic methylphenidate therapy 45 minutes after ingesting a dose of venlafaxine. It is unclear if the reaction was the result of a drug interaction. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical management should be implemented.
    Dextromethorphan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dextromethorphan; Guaifenesin: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dextromethorphan; Guaifenesin; Potassium Guaiacolsulfonate: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dextromethorphan; Guaifenesin; Pseudoephedrine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dextromethorphan; Promethazine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Dextromethorphan; Quinidine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as dextromethorphan. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of dextromethorphan may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dextromethorphan, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Diclofenac: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Diclofenac; Misoprostol: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Diflunisal: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Diphenhydramine; Ibuprofen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Diphenhydramine; Naproxen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Dipyridamole: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Diuretics: (Moderate) Patients receiving a diuretic during treatment with venlafaxine may be at greater risk of developing syndrome of inappropriate antidiuretic hormone secretion (SIADH). Hyponatremia due to SIADH may occur during therapy with SNRIs, including venlafaxine. Cases involving serum sodium levels lower than 110 mmol/l have been reported. Hyponatremia may be potentiated by agents which can cause sodium depletion such as diuretics. Discontinuation of the SNRI should be considered in patients who develop symptomatic hyponatremia.
    Dolasetron: (Major) Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as dolasetron, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day. In addition, because of the potential risk and severity of serotonin syndrome, use caution when administering these drugs together. If serotonin syndrome is suspected, discontinue dolasetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome has been reported when 5HT3 receptor antagonists have been used in combination with other serotonergic drugs. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Doxepin: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.
    Duloxetine: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs) including venlafaxine, desvenlafaxine, duloxetine, levomilnacipran, and milnacipran should not be coadministered with each other. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Eletriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Eptifibatide: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Ergot alkaloids: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as ergot alkaloids. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving these combinations should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Escitalopram: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms.
    Esomeprazole; Naproxen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Etodolac: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Famotidine; Ibuprofen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Fenoprofen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Fentanyl: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering desvenlafaxine with other drugs that have serotonergic properties such as fentanyl. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring is recommended during co-administration of fentanyl and desvenlafaxine for signs and symptoms of serotonin syndrome or other serious effects.
    Fluoxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of fluoxetine may be necessary during concurrent use of desvenlafaxine; the dose of CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Fluoxetine; Olanzapine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of fluoxetine may be necessary during concurrent use of desvenlafaxine; the dose of CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Fluphenazine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Flurbiprofen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Fluvoxamine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms.
    Frovatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Gefitinib: (Major) Monitor for an increased incidence of gefitinib-related adverse effects if gefitinib and desvenlafaxine are used concomitantly. Gefitinib is metabolized significantly by CYP3A4 and to a lesser extent by CYP2D6. Desvenlafaxine is a CYP2D6 inhibitor; however, clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day. Coadministration may decrease the metabolism of gefitinib and increase gefitinib concentrations. While the manufacturer of gefitinib has provided no guidance regarding its use with CYP2D6 inhibitors, in patients with poor CYP2D6 metabolism, the mean exposure to gefitinib was 2-fold higher when compared to extensive metabolizers; the contribution of drugs that inhibit CYP2D6 on gefitinib exposure has not been evaluated. The manufacturer of desvenlafaxine recommends that the dose of primary substrates of CYP2D6 be reduced when coadministered with Pristiq 400 mg/day; however, CYP2D6 is not the primary route of metabolism for gefitinib.
    Granisetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering granisetron with other drugs that have serotonergic properties such as desvenlafaxine. If serotonin syndrome is suspected, discontinue granisetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Haloperidol: (Major) Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as haloperidol, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Hydrochlorothiazide, HCTZ; Metoprolol: (Major) Dosage adjustments of some beta-blockers may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as propranolol, metoprolol, or nebivolol, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Hydrochlorothiazide, HCTZ; Propranolol: (Major) Dosage adjustments of some beta-blockers may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as propranolol, metoprolol, or nebivolol, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Hydrocodone; Ibuprofen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued. (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Ibuprofen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Ibuprofen; Oxycodone: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Ibuprofen; Pseudoephedrine: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Imipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Indomethacin: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Isoniazid, INH: (Major) Due to the risk of serotonin syndrome, concurrent use of desvenlafaxine and medications with MAO-like activity, such as isoniazid, INH, should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO and may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with serotonin norepinephrine reuptake inhibitors. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Due to the risk of serotonin syndrome, concurrent use of desvenlafaxine and medications with MAO-like activity, such as isoniazid, INH, should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO and may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with serotonin norepinephrine reuptake inhibitors. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued.
    Isoniazid, INH; Rifampin: (Major) Due to the risk of serotonin syndrome, concurrent use of desvenlafaxine and medications with MAO-like activity, such as isoniazid, INH, should be avoided if possible. Isoniazid is chemically related to iproniazid, a drug that was known to possess MAO inhibiting activity. Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO and may possess enough MAO inhibiting activity to produce clinical symptoms consistent with serotonergic excess when combined with serotonin norepinephrine reuptake inhibitors. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued.
    Kava Kava, Piper methysticum: (Moderate) Any substances that act on the CNS, such as desvenlafaxine, may interact with the phytomedicinals kava kava, Piper methysticum. These interactions are probably pharmacodynamic in nature, or result from additive mechanisms of action.
    Ketoprofen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Ketorolac: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Lansoprazole; Naproxen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Levomilnacipran: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs), including levomilnacipran and desvenlafaxine, should not be coadministered. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Linezolid: (Severe) The use of linezolid with serotonin norepinephrine reuptake inhibitors (SNRIs) such as desvenlafaxine is contraindicated due to the potential for serotonin syndrome. Linezolid is an antibiotic that also possesses weak non-selective MAO-inhibiting activity which could have additive effects with SNRIs on central serotonin activity. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In a patient who requires urgent treatment of a psychiatric condition, interventions other than an SNRI, including hospitalization, should be considered. In some cases, a patient already receiving desvenlafaxine may require urgent treatment with linezolid. If acceptable alternatives to linezolid are not available and the potential benefits of linezolid are determined to outweigh the risks of serotonin syndrome in an individual patient, desvenlafaxine should be stopped promptly, and linezolid can be administered. The patient should be monitored for symptoms of serotonin syndrome for 7 days or until 24 hours after the last dose of linezolid, whichever comes first. Therapy with desvenlafaxine may be resumed 24 hours after the last dose of linezolid.
    Lisdexamfetamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as lisdexamfetamine. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 1 to 2 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving SNRIs and amphetamines should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Lithium: (Major) Lithium is an effective augmenting agent to antidepressants in treatment-resistant depression; however, lithium has been reported to have central serotonin-enhancing effects and may interact pharmacodynamically with desvenlafaxine to cause serotonin syndrome. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients should be informed of the possible increased risk of serotonin syndrome. If serotonin syndrome occurs, desvenlafaxine and lithium should be discontinued and symptomatic treatment should be initiated. One systematic review and meta-analysis of lithium augmentation of tricyclic and second generation antidepressants in major depression found no difference in discontinuation rate due to adverse events between the lithium and placebo groups. However, some data indicate that the elderly may have increased susceptibility to neurotoxicity (e.g., fine tremor, ataxia, severe memory impairment, and/or gait disturbances) from concurrent use of lithium and antidepressants, despite therapeutic lithium concentrations.
    Loperamide: (Moderate) The plasma concentration of loperamide, a CYP2D6 substrate, may be increased when administered concurrently with desvenlafaxine, a CYP2D6 inhibitor. If these drugs are used together, monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest).
    Loperamide; Simethicone: (Moderate) The plasma concentration of loperamide, a CYP2D6 substrate, may be increased when administered concurrently with desvenlafaxine, a CYP2D6 inhibitor. If these drugs are used together, monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest).
    Lorcaserin: (Major) Based on the mechanism of action of lorcaserin and the theoretical potential for serotonin syndrome, use with extreme caution in combination with other drugs that may affect the serotonergic neurotransmitter systems, including, serotonin norepinephrine reuptake inhibitors. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or Neuroleptic Malignant Syndrome (NMS) like signs and symptoms.
    Magnesium Salicylate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Meclofenamate Sodium: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Mefenamic Acid: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Meloxicam: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Meperidine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as meperidine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Meperidine; Promethazine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as meperidine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Methamphetamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as amphetamines. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In addition, the MAOI activity of amphetamines may be of concern with the use of drugs that have serotonergic activity. A man developed marked agitation, anxiety, diaphoresis, shivering, tachycardia, tremor, generalized hypertonia, hyperreflexia, 1 to 2 beats of inducible ankle clonus, frequent myoclonic jerking, and tonic spasm of the right side of his orbicularis oris muscle while taking dexamphetamine and venlafaxine. Cessation of both drugs and administration of cyproheptadine led to a stepwise heart rate reduction and complete symptom resolution. Patients receiving an SNRI and an amphetamine should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The SNRI and amphetamine should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued.
    Methylene Blue: (Severe) Concurrent use of methylene blue and serotonin norepinephrine reuptake inhibitors (SNRIs) (e.g., venlafaxine, duloxetine, desvenlafaxine, milnacipran) should generally be avoided due to the potential for serotonin syndrome. Results from an in vitro study indicate that methylene blue is a potent, reversible inhibitor of the monoamine oxidase type A enzyme (MAO-A). MAO-A is responsible for the metabolism of serotonin; therefore, concurrent use of an MAO-A inhibitor with serotonergic agents such as SNRIs may result in a clinically significant interaction. Cases of serotonin syndrome have been reported, primarily following administration of standard infusions of methylene blue (1 to 8 mg/kg) as a visualizing agent in parathyroid surgery, in patients receiving selective serotonin reuptake inhibitors, SNRIs, or clomipramine. It is not known if patients receiving other serotonergic psychiatric agents with intravenous methylene blue are at a comparable risk or if methylene blue administered by other routes (e.g., orally, local injection) or in doses less than 1 mg/kg IV can produce a similar outcome. One case report suggests that serotonin toxicity may have occurred post-operatively following administration of standard infusions of methylene blue in a patient receiving duloxetine. The patient experienced disorientation, a mildly elevated temperature, tachycardia, elevated blood pressure, mild agitation, and nystagmus. In a separate case, a patient who had been receiving venlafaxine developed expressive aphasia, confusion, and disinhibition following a methylene blue infusion. The authors concluded that methylene blue toxicity had occurred; however, they did not exclude the possibility of a drug interaction based upon previous reports of an interaction between injectable methylene blue and selective serotonin reuptake inhibitors (SSRIs). Published interaction reports between intravenously administered methylene blue and serotonergic psychiatric agents have documented symptoms including lethargy, confusion, delirium, agitation, aggression, obtundation, myoclonus, expressive aphasia, hypertonia, pyrexia, elevated blood pressure, seizures, and/or coma. Signs and symptoms of serotonin syndrome include fever, diaphoresis, shivering, myoclonus, tremor, tachycardia, diarrhea, nausea, headache, incoordination, mental status changes (e.g., agitation, confusion), hyperreflexia, seizures, and coma. If emergent treatment with methylene blue is required in a patient receiving an SNRI, the SNRI must be stopped immediately and the patient should be monitored for symptoms of CNS toxicity for two weeks or until 24 hours after the last dose of methylene blue, whichever comes first. During non-emergent use of methylene blue, the SNRI should be stopped at least 2 weeks prior to methylene blue treatment, but also taking into consideration the half-life of the SNRI being discontinued.
    Methylphenidate: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as methylphenidate and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome has been reported during concurrent use of other serotonergic antidepressants (i.e., SSRIs) and methylphenidate. There is also a case of a neuroleptic malignant syndrome-like reaction occurring in a child on chronic methylphenidate therapy 45 minutes after ingesting a dose of venlafaxine. It is unclear if the reaction was the result of a drug interaction. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving this combination should be monitored for the emergence of serotonin syndrome. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical management should be implemented.
    Metoclopramide: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that are dopamine antagonists such as metoclopramide. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. In addition, metoclopramide may cause extrapyramidal reactions (e.g., acute dystonic reactions, pseudo-parkinsonism, akathisia, or tardive dyskinesia) and is contraindicated with other drugs that are likely to cause extrapyramidal effects. Dystonia, akathisia, trismus, torticollis, dyskinesia, tardive dyskinesia, pseudo-parkinsonism, and/or extrapyramidal disorder (unspecified) have been reported during use of SNRIs; however, these effects appear uncommon. Patients receiving concurrent treatment with dopamine antagonists may be more predisposed to these reactions. Case reports documenting an interaction between metoclopramide and other serotonergic agents (i.e., SSRIs) suggest that serotonin syndrome and/or movement disorders are possible during combined use of metoclopramide and SNRIs. Patients receiving SNRIs and metoclopramide should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
    Metoprolol: (Major) Dosage adjustments of some beta-blockers may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as propranolol, metoprolol, or nebivolol, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Mexiletine: (Major) Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6. such as mexiletine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Milnacipran: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs) including venlafaxine, desvenlafaxine, duloxetine, levomilnacipran, and milnacipran should not be coadministered. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Mirtazapine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as mirtazapine and desvenlafaxine. Cases of serotonin syndrome have been reported between mirtazapine and other antidepressants such as selective serotonin reuptake inhibitors (SSRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome occurs, serotonergic agents should be discontinued and appropriate medical treatment should be implemented.
    Monoamine oxidase inhibitors: (Severe) Due to the risk of serotonin syndrome, monoamine oxidase inhibitors (MAOIs) intended to treat psychiatric disorders are contraindicated for use with serotonin norepinephrine reuptake inhibitors (SNRIs). MAOIs should not be used within 5 days of discontinuing treatment with duloxetine or within 7 days of discontinuing treatment with other SNRIs. Conversely, SNRIs should not be initiated within 14 days of stopping an MAOI. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Morphine: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Morphine; Naltrexone: (Major) Because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Nabumetone: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Naproxen: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Naproxen; Pseudoephedrine: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Naproxen; Sumatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen. (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Naratriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Nebivolol: (Major) Avoid the concomitant use of nebivolol and desvenlafaxine. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as desvenlafaxine, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible. The manufacturer of desvenlafaxine states no dosage adjustment of nebivolol is required when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of nebivolol should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day. Patients should be monitored for increased toxicity as well as increased therapeutic effect.
    Nebivolol; Valsartan: (Major) Avoid the concomitant use of nebivolol and desvenlafaxine. Nebivolol is metabolized by CYP2D6. Although data are lacking, CYP2D6 inhibitors, such as desvenlafaxine, could potentially increase nebivolol plasma concentrations via CYP2D6 inhibition; the clinical significance of this potential interaction is unknown, but an increase in adverse effects is possible. The manufacturer of desvenlafaxine states no dosage adjustment of nebivolol is required when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of nebivolol should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day. Patients should be monitored for increased toxicity as well as increased therapeutic effect.
    Nefazodone: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as nefazodone. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Netupitant; Palonosetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering palonosetron with other drugs that have serotonergic properties such as desvenlafaxine. If serotonin syndrome is suspected, discontinue palonosetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends the dose reduction of CYP2D6 substrates, such as palonosetron,by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Nonsteroidal antiinflammatory drugs: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Nortriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.
    Ondansetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering ondansetron with other drugs that have serotonergic properties such as desvenlafaxine. If serotonin syndrome is suspected, discontinue ondansetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Oxaprozin: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Palonosetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering palonosetron with other drugs that have serotonergic properties such as desvenlafaxine. If serotonin syndrome is suspected, discontinue palonosetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends the dose reduction of CYP2D6 substrates, such as palonosetron,by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Paroxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of fluoxetine or paroxetine may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6 be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Pentazocine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Pentazocine; Naloxone: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as pentazocine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving this combination should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Perphenazine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Perphenazine; Amitriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day. (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Phentermine: (Moderate) Use phentermine and selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs) together with caution; use together may be safe and efficacious for some patients based on available data, provided the patient is on a stable antidepressant regimen and receives close clinical monitoring. Regular appointments to assess the efficacy of the weight loss treatment, the emergence of adverse events, and blood pressure monitoring are recommended. Watch for excessive serotonergic effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome or cardiovascular or pulmonary effects when combined with serotonergic agents. One case report describes adverse reactions with phentermine and fluoxetine. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses, and that phentermine does not additionally increase plasma serotonin levels when combined with other serotonergic agents. In large controlled clinical studies, patients were allowed to start therapy with phentermine or phentermine; topiramate extended-release for obesity along with their antidepressants (e.g., SSRIs or SNRIs, but not MAOIs or TCAs) as long as the antidepressant dose had been stable for at least 3 months prior to the initiation of phentermine, and the patient did not have suicidal ideation or more than 1 episode of major depression documented. In analyses of the results, therapy was generally well tolerated, especially at lower phentermine doses, based on discontinuation rates and reported adverse events. Because depression and obesity often coexist, the study data may be important to providing optimal therapies.
    Phentermine; Topiramate: (Moderate) Use phentermine and selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs) together with caution; use together may be safe and efficacious for some patients based on available data, provided the patient is on a stable antidepressant regimen and receives close clinical monitoring. Regular appointments to assess the efficacy of the weight loss treatment, the emergence of adverse events, and blood pressure monitoring are recommended. Watch for excessive serotonergic effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome or cardiovascular or pulmonary effects when combined with serotonergic agents. One case report describes adverse reactions with phentermine and fluoxetine. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses, and that phentermine does not additionally increase plasma serotonin levels when combined with other serotonergic agents. In large controlled clinical studies, patients were allowed to start therapy with phentermine or phentermine; topiramate extended-release for obesity along with their antidepressants (e.g., SSRIs or SNRIs, but not MAOIs or TCAs) as long as the antidepressant dose had been stable for at least 3 months prior to the initiation of phentermine, and the patient did not have suicidal ideation or more than 1 episode of major depression documented. In analyses of the results, therapy was generally well tolerated, especially at lower phentermine doses, based on discontinuation rates and reported adverse events. Because depression and obesity often coexist, the study data may be important to providing optimal therapies.
    Piroxicam: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Prasugrel: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Procarbazine: (Major) Concurrent use of procarbazine and serotonin norepinephrine reuptake inhibitors (SNRIs) should be avoided if possible. Procarbazine is a weak monoamine oxidase inhibitor (MAOI). Since monoamine oxidase type A deaminates serotonin, administration of a non-selective MAO inhibitor concurrently with an SNRI can lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If combination therapy is necessary, patients should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    Prochlorperazine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Propranolol: (Major) Dosage adjustments of some beta-blockers may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as propranolol, metoprolol, or nebivolol, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Protriptyline: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Rasagiline: (Major) It is recommended to avoid concurrent use of rasagiline and antidepressants, including serotonin norepinephrine reuptake inhibitors (SNRIs). Severe CNS toxicity with hyperpyrexia has been reported during concurrent use of antidepressants and selective or non-selective MAOIs. During post-marketing use of rasagiline, non-fatal cases of serotonin syndrome have been reported during concomitant antidepressant administration. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. At least 2 weeks should elapse between stopping rasagiline treatment and beginning therapy with any antidepressant. Conversely, when discontinuing the antidepressant, it is advisable to wait the length of 4 to 5 half lives of the individual agent being discontinued prior to initiation with rasagiline.
    Remifentanil: (Moderate) Concurrent use of remifentanil with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. If concurrent use is necessary, closely monitor the patient, particularly during remifentanil initiation and dosage adjustment. Discontinue remifentanil if serotonin syndrome is suspected.
    Reteplase, r-PA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Risperidone: (Major) Coadministration of risperidone, a CYP2D6 substrate, and desvenlafaxine, a CYP2D6 inhibitor, may increase plasma concentrations of risperidone. Clinical studies have shown desvenlafaxine does not have a clinically relevant effect on CYP2D6 metabolism at doses less than 100 mg/day; hence, per desvenlafaxine product labeling, CYP2D6 substrates can be dosed at the original level when desvenlafaxine doses are 100 mg or less or when desvenlafaxine is discontinued. For desvenlafaxine doses more than 400 mg, product labeling recommends to reduce the risperidone dose by one-half.
    Rizatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Rofecoxib: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Safinamide: (Severe) Safinamide is contraindicated for use with serotonin norepinephrine reuptake inhibitors (SNRIs) due to the risk of serotonin syndrome. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. At least 14 days should elapse between the discontinuation of safinamide and the initiation of an SNRI.
    Salicylates: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Salsalate: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving aspirin, ASA or other salicylates which affect hemostasis. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Serotonin-Receptor Agonists: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Sertraline: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, selective serotonin reuptake inhibitors (SSRIs) should generally not be administered with serotonin norepinephrine reuptake inhibitors like desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Discontinuation symptoms have been reported when switching from other antidepressants to desvenlafaxine. It may be advisable to taper the previous antidepressant to minimize discontinuation symptoms.
    Sibutramine: (Major) Sibutramine is a serotonin reuptake inhibitor. Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering sibutramine with other drugs that have serotonergic properties such as serotonin norepinephrine reuptake inhibitors (SNRIs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Patients receiving sibutramine in combination with an SNRI should be monitored for the emergence of serotonin syndrome or neuroleptic malignant syndrome-like reactions.
    St. John's Wort, Hypericum perforatum: (Major) Due to possible additive effects on serotonin concentrations, it is advisable to avoid combinations of St. John's wort, Hypericum perforatum with serotonin norepinephrine reuptake inhibitors (SNRIs). Interactions between SNRIs and serotonergic agents can lead to serious reactions including serotonin syndrome or neuroleptic malignant syndrome-like reactions. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome.
    Streptokinase: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Sulindac: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Sumatriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Tapentadol: (Major) Caution is advised when tapentadol is coadministered with serotonin norepinephrine reuptake inhibitors as this combination may result in excessive concentrations of serotonin and/or norepinephrine and increase the potential for adverse cardiac events and serotonin syndrome development. If concomitant treatment is clinically warranted, careful observation of the patient is advised, especially during initiation of the second therapy and after dosage adjustments (increases) of either agent.
    Tedizolid: (Minor) Use caution with the concurrent use of tedizolid and serotonin norepinephrine reuptake inhibitors (SNRIs) due to the theoretical risk of serotonin sydrome. Animal studies did not predict serotonergic effects; however, patients on concurrent SNRIs were excluded from clinical trials. Additionally, tedizolid is an antibiotic that is also a weak reversible, non-selective MAO inhibitor and monoamine oxidase type A deaminates serotonin; therefore, coadministration theoretically could lead to serious reactions including serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Tenecteplase, TNK-tPA: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Tetrabenazine: (Major) Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as tetrabenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Thiethylperazine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Thioridazine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Thrombolytic Agents: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Ticagrelor: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Ticlopidine: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Tirofiban: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Tolmetin: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Tolterodine: (Major) Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as tolterodine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Tramadol: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In one case, the addition of tramadol to extended-release venlafaxine (300 mg/day) and mirtazapine (30 mg/day) likely caused serotonin syndrome. A patient developed agitation, confusion, severe shivering, diaphoresis, myoclonus, hyperreflexia, mydriasis, tachycardia, and fever within 7 weeks of taking tramadol 400 mg daily. He had taken 300 mg tramadol without difficulty. Discontinuation of the 3 drugs and rehydration led to symptom resolution over 36 hours. Reinstitution of the antidepressants 3 days after patient presentation was uneventful. In addition, although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as tramadol, be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.
    Trazodone: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering drugs that have serotonergic properties such as trazodone and desvenlafaxine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical treatment should be implemented.
    Trifluoperazine: (Major) Dosage adjustments of some phenothiazines may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer that primary substrates of CYP2D6, such as perphenazine, be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Trimipramine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tricyclic antidepressants (TCAs). Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If serotonin syndrome is suspected, desvenlafaxine and concurrent serotonergic agents should be discontinued. Dosage adjustments of TCAs may be necessary during concurrent use of desvenlafaxine. Although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as desipramine, doxepin, clomipramine, and imipramine be dosed at the original level when co-administered with desvenlafaxine 100 mg or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if co-administered with desvenlafaxine 400 mg/day.
    Urokinase: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving thrombolytic agents. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with medications which impair platelet function and to promptly report any bleeding events to the practitioner.
    Valdecoxib: (Moderate) Platelet aggregation may be impaired by desvenlafaxine due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving nonsteroidal antiinflammatory drugs (NSAIDs). Patients should be monitored for signs and symptoms of bleeding while taking desvenlafaxine with NSAIDs.
    Valerian, Valeriana officinalis: (Moderate) Any substances that act on the CNS, such as desvenlafaxine, may interact with the phytomedicinals kava kava, Piper methysticum. These interactions are probably pharmacodynamic in nature, or result from additive mechanisms of action.
    Venlafaxine: (Severe) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, serotonin norepinephrine reuptake inhibitors (SNRIs) including venlafaxine, desvenlafaxine, duloxetine, levomilnacipran, and milnacipran should not be coadministered with each other. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Vilazodone: (Major) Due to possible additive effects on serotonin concentrations, it is advisable to avoid combining serotonin norepinephrine reuptake inhibitors (SNRIs) with vilazodone. Interactions between vilazodone and serotonergic agents can lead to serotonin syndrome. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Patients receiving vilazodone and an SNRI should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. Vilazodone and the SNRI should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated.
    Vorapaxar: (Moderate) Platelet aggregation may be impaired by serotonin norepinephrine reuptake inhibitors (SNRIs) due to platelet serotonin depletion, possibly increasing the risk of a bleeding complication (e.g., gastrointestinal bleeding, ecchymoses, epistaxis, hematomas, petechiae, hemorrhage) in patients receiving platelet inhibitors. Patients should be instructed to monitor for signs and symptoms of bleeding while taking an SNRI with a platelet inhibitor and to promptly report any bleeding events to the practitioner.
    Vortioxetine: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, vortioxetine should generally not be administered with serotonin norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine, desvenlafaxine, duloxetine, and milnacipran. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. If serotonin syndrome is suspected, vortioxetine and concurrent serotonergic agents should be discontinued.
    Zolmitriptan: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering a selective serotonin norepinephrine reuptake inhibitor (SNRI) like desvenlafaxine with other drugs that have serotonergic properties such as serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan) because of the potential risk and severity of serotonin syndrome. Serotonin syndrome has been reported during concurrent use of drugs from these drug classes. Some patients had used the combination previously without incident when serotonin syndrome occurred. Some cases have involved hospitalization. Serotonin syndrome consists of symptoms such as mental status changes (e.g., agitation, confusion, hallucinations), diaphoresis, hyperreflexia, hypertension, diarrhea, fever, tremor, and, in some instances, respiratory failure. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Careful monitoring for serotonin syndrome is recommended if combination therapy with is required. Risk factors can include a recent dose increase of the SNRI or the addition of other serotonergic medications to an existing SNRI regimen.
    Zolpidem: (Moderate) Disorientation, delusions, or hallucinations have been reported rarely during co-administration of zolpidem and antidepressants. The duration of the visual hallucinations has ranged from 30 minutes to 7 hours. The interaction is thought to be pharmacodynamic in nature; therefore, a similar reaction is possible with dexvenlafaxine. Data from a clinical study in which SSRI-treated patients were given immediate-release zolpidem revealed that four of the seven discontinuations during double-blind treatment with zolpidem (n = 95) were associated with impaired concentration, continuing or aggravated depression, and manic reaction.

    PREGNANCY AND LACTATION

    Pregnancy

    Desvenlafaxine is excreted in human breast milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue breast-feeding or to discontinue desvenlafaxine. Data describing the clinical effects of infant exposure after maternal desvenlafaxine administration are not available. However, desvenlafaxine is the active metabolite of venlafaxine, and several small case series have described infants who were breast-fed by mothers taking venlafaxine. The majority of infants had measurable desvenlafaxine plasma concentrations. Consider if treatment alternatives are appropriate. Due to individual variability in response to antidepressants, it may be prudent to continue the existing regimen if ongoing treatment is deemed necessary during breast-feeding. However, because a pooled analysis found that maternal use of sertraline, along with nortriptyline and paroxetine, usually produced undetectable or low drug concentrations in infant serum, these agents may be the preferred antidepressants when initiating antidepressant therapy in a breast-feeding mother. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    MECHANISM OF ACTION

    Decreased adrenergic and serotoninergic neurotransmission has been proposed to play a key role in the etiology of depression. It is theorized that serotonin (5-HT) and norepinephrine (NE) reuptake inhibitors work by blocking the central presynaptic reuptake of 5-HT and NE, resulting in an increased sustained level of these neurotransmitters. Changes in postsynaptic receptor characteristics with chronic administration may also contribute to the efficacy of antidepressants. Serotonin is a neurotransmitter which regulates an extensive modulatory behavioral system in the brain. The serotoninergic system is known to modulate mood, emotion, sleep, and appetite and thus is implicated in the control of numerous behavioral and physiological functions. Norepinephrine is an adrenergic neurotransmitter which appears to be involved in a range of psychological processes, including mood stabilization, sleep regulation, overall alertness and arousal, and in regulating response to stressors which might initiate or exacerbate depressive symptomatology. Desvenlafaxine does not appear to possess monoamine oxidase inhibiting activity.

    PHARMACOKINETICS

    Desvenlafaxine is administered orally. Desvenlafaxine is the major active metabolite and an enantiomer of racemic venlafaxine. Animal studies have shown that peak plasma and brain concentrations of the drug occur 30 minutes following a subcutaneous dose of 30 mg/kg. In the presence of a 5-HT1A antagonist, serotonin levels in the hypothalamus increased 225% after 1 hour. Norepinephrine levels increased 44% after 3 hours, while dopamine remained unchanged. Desvenlafaxine was not detectable in plasma 24 hours following the dose.
     
    Pharmacokinetic study results obtained in humans are available from administration of the parent compound venlafaxine and subsequent observation of desvenlafaxine kinetics. These results indicate that protein binding of desvenlafaxine is 30%. The primary metabolite is the O-glucuronide conjugate of the drug. The elimination half-life is 11 hours.
     
    Affected cytochrome P450 isoenzymes and drug transporters: CYP2D6
    The manufacturer recommends that primary substrates of CYP2D6 be dosed at the original level when coadministered with desvenlafaxine 100 mg/day or lower or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.