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  • CLASSES

    Serotonin Norepinephrine Reuptake Inhibitor Antidepressants, SNRIs

    BOXED WARNING

    Children, suicidal ideation

    Safety and efficacy of desvenlafaxine have not been established for the treatment of depression in children or adolescents less than 18 years of age. Efficacy for treating major depressive disorder (MDD) was not demonstrated in two 8-week controlled trials of 587 pediatric patients 7 to 17 years of age. In addition, more patients receiving desvenlafaxine than placebo had a decrease in body weight of 3.5% or greater from their baseline weight (14% to 22% vs. 7%). During long-term extension studies in the same population, the mean changes in weight approximated expected changes based on data from age and gender-matched controls. In a pooled analysis of placebo-controlled trials of antidepressants (n = 4,500 pediatrics and 77,000 adults), there was an increased risk for suicidal thoughts and behaviors in patients 24 years of age and younger receiving an antidepressant versus placebo, with considerable variation in the risk of suicidality among drugs. The difference in absolute risk of suicidal thoughts and behaviors across different indications was highest in those with major depression. No suicides occurred in any of the pediatric trials. Nevertheless, the need for an antidepressant in children, adolescents, or young adults for any use must be weighed against the risk of suicidality; it is unknown if this risk extends to long-term use. All patients should be monitored for symptom worsening or suicidality, especially at treatment initiation or after dose changes. Caregivers and/or patients should immediately notify the prescriber of changes in behavior or suicidal ideation. A change to the treatment regimen or discontinuation of desvenlafaxine may be necessary in patients with emerging suicidality or worsening depression.

    DEA CLASS

    Rx

    DESCRIPTION

    Oral serotonin norepinephrine reuptake inhibitor (SNRI) antidepressant
    Used in adults for major depression
    Increased risk of suicidality during the initial stages of treatment in pediatric and young adult patients

    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
    Adults

    50 mg PO once daily, initially. Usual dose: 50 mg/day. In clinical studies, doses of 50 to 400 mg/day were shown to be effective, although no additional benefit was demonstrated at doses more than 50 mg/day and adverse reactions and discontinuations were more frequent at higher doses. Coadministration of certain drugs may need to be avoided or dosage adjustments may be necessary; review drug interactions. Periodically reassess the need for continued treatment. Guidance on the appropriate length of treatment is available through the American Psychiatric Association treatment guidelines for patients with major depressive disorder.

    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. 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): No dosage adjustment 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 51 to 80 mL/minute: No dosage adjustment needed.
    CrCl 30 to 50 mL/minute: 50 mg PO once daily is the maximum recommended dosage.
    CrCl 15 to 29 mL/minute: 25 mg PO once daily or 50 mg PO every other day is the maximum recommended dosage.
    End-stage renal disease (CrCl less than 15 mL/minute): 25 mg PO once daily or 50 mg PO every other day is the maximum recommended dosage.
     
    Intermittent hemodialysis:
    See the recommended maximum dosage based on CrCl. Supplemental doses should not be given to patients after dialysis.

    ADMINISTRATION

    Oral Administration

    May administer with or without food.

    Oral Solid Formulations

    Extended-release tablets: Patients should swallow tablets whole. Do not divide, cut, chew, crush, or dissolve.

    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:
    - Protect from heat
    - Store at controlled room temperature (between 68 and 77 degrees F)

    CONTRAINDICATIONS / PRECAUTIONS

    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

    Abrupt discontinuation of desvenlafaxine should be avoided. Advise patients not to stop taking desvenlafaxine without talking to their healthcare provider and to be aware that discontinuation effects may occur if the drug is abruptly stopped. When discontinuing desvenlafaxine, gradual tapering of the dose is recommended when possible to minimize the risk of discontinuation symptoms. Individualize the dose taper; some patients may require several months of a tapered dosing regimen in order to minimize discontinuation symptoms. If intolerable symptoms occur following a dose decrease or upon discontinuation, the health care provider may resume the previous dose or continue a more gradual dose decrease. Withdrawal symptoms that have been reported with abrupt discontinuation or tapering of desvenlafaxine include abnormal dreams, headache, insomnia, dizziness, nausea/vomiting, paresthesia, irritability, fatigue, diarrhea, anxiety, decreased appetite, vertigo, hyperhidrosis, and tremors. Serious discontinuation symptoms have been reported and may include aggression, violent behavior, suicidal thoughts or completed suicide. Other adverse effects noted in these reports include changes in vision (such as blurry vision or trouble focusing) and increased blood pressure. Other adverse effects reported with the discontinuation of SNRIs (including desvenlafaxine) and SSRIs include irritability, fatigue, emotional lability, ringing of the ears, and convulsions. Patients should be carefully monitored if abrupt discontinuation of desvenlafaxine is necessary.

    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 efficacy of desvenlafaxine have not been established for the treatment of depression in children or adolescents less than 18 years of age. Efficacy for treating major depressive disorder (MDD) was not demonstrated in two 8-week controlled trials of 587 pediatric patients 7 to 17 years of age. In addition, more patients receiving desvenlafaxine than placebo had a decrease in body weight of 3.5% or greater from their baseline weight (14% to 22% vs. 7%). During long-term extension studies in the same population, the mean changes in weight approximated expected changes based on data from age and gender-matched controls. In a pooled analysis of placebo-controlled trials of antidepressants (n = 4,500 pediatrics and 77,000 adults), there was an increased risk for suicidal thoughts and behaviors in patients 24 years of age and younger receiving an antidepressant versus placebo, with considerable variation in the risk of suicidality among drugs. The difference in absolute risk of suicidal thoughts and behaviors across different indications was highest in those with major depression. No suicides occurred in any of the pediatric trials. Nevertheless, the need for an antidepressant in children, adolescents, or young adults for any use must be weighed against the risk of suicidality; it is unknown if this risk extends to long-term use. All patients should be monitored for symptom worsening or suicidality, especially at treatment initiation or after dose changes. Caregivers and/or patients should immediately notify the prescriber of changes in behavior or suicidal ideation. A change to the treatment regimen or discontinuation of desvenlafaxine may be necessary in patients with emerging suicidality or worsening depression.

    MAOI therapy

    Desvenlafaxine is contraindicated for concomitant use in patients receiving monoamine oxidase inhibitor therapy (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 concomitant serotonergic agents and initiate supportive treatment. Do not give desvenlafaxine with other SNRIs. 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, GI 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., GI 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. For patients taking warfarin, carefully monitor coagulation indices when initiating, titrating, or discontinuing desvenlafaxine. Patients taking desvenlafaxine should be informed about the risk of bleeding associated with concurrent use of antiplatelet agents or anticoagulants and 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 use of antidepressants, including desvenlafaxine, should be avoided in patients with untreated anatomically narrow angles. 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.

    Sexual dysfunction

    Sexual dysfunction can occur in individuals taking desvenlafaxine. For males, these effects may present as ejaculatory failure or delay, decreased libido, and/or erectile dysfunction. Females may experience decreased libido and delayed or absent orgasm. Prescribers should discuss sexual function prior to initiating treatment with desvenlafaxine and throughout treatment and obtain a detailed history and timeline of any changes in sexual function to determine whether the changes are medication-related or may be attributed to the underlying psychiatric disorder. Clinicians should also discuss management strategies and treatment options with patients.

    Eclampsia, neonates, obstetric delivery, pregnancy

    There are no adequate and well-controlled studies regarding the use of desvenlafaxine during human pregnancy; however, epidemiologic studies of venlafaxine, the parent compound of desvenlafaxine, have not shown a clear association with adverse developmental outcomes when used during pregnancy. In animal studies, there were no teratogenic effects at doses of desvenlafaxine above the maximum recommended human dose; however, other fetal complications were observed. Consider the risks of untreated depression during pregnancy as well as the potential fetal risks. When treating a pregnant individual with a serotonin norepinephrine reuptake inhibitor (SNRI) or other serotonergic agent during the third trimester, neonatal discontinuation symptoms may occur 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 obstetric delivery; symptoms have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor, jitteriness, irritability, and constant crying. These features are consistent with serotonin syndrome or a drug discontinuation syndrome. In terms of maternal risk, exposure to SNRIs in mid to late pregnancy may increase the risk of eclampsia and use near obstetric delivery may increase the risk for postpartum hemorrhage. If clinically feasible, gradual tapering of the medication prior to delivery may be considered. The National Pregnancy Registry for Antidepressants is dedicated to evaluating the safety of antidepressant medications that may be taken during pregnancy to treat a wide range of mood, anxiety, or psychiatric disorders. The pregnancy registry monitors pregnancy outcomes; information about the registry can be obtained at https://womensmentalhealth.org/research/pregnancyregistry/antidepressants/ or by calling 1-866-961-2388.

    Breast-feeding

    According to the manufacturer, desvenlafaxine should only be considered for use during breast-feeding if the potential benefit to the mother outweighs the potential risk to the infant, taking into account the clinical need of the mother and any potential adverse effects on the breastfed infant from desvenlafaxine or from the underlying maternal condition. Limited data indicate that low levels of desvenlafaxine are present in human breast milk. In addition, several small case series have described infants who were breastfed by mothers taking venlafaxine, the parent compound of desvenlafaxine, and the majority of infants had measurable desvenlafaxine plasma concentrations. In one lactation study, 10 breast-feeding women were receiving 50 mg to 150 mg of desvenlafaxine daily for postpartum depression. The mean relative infant dose was calculated to be 6.8% following assessment of desvenlafaxine steady-state samples of foremilk and hindmilk. No adverse reactions were observed in the infants. 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

    No overall differences in safety or efficacy were observed between geriatric and younger adult patients during premarketing clinical studies for desvenlafaxine. 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.[34940] According to the Beers Criteria, SNRIs are considered potentially inappropriate medications (PIMs) in older adults and should be avoided in elderly patients with a history of falls or fractures, unless safer alternatives are not available since SNRIs can produce ataxia, impaired psychomotor function, syncope, and additional falls. If desvenlafaxine must be used in an elderly patient with a history of falls or fractures, consider reducing the use of other CNS-active medications that increase the risk of falls and fractures and implement strategies to reduce fall risk. All 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.[63923] The federal Omnibus Budget Reconciliation Act (OBRA) regulates the use of antidepressants in residents of long-term care facilities; the duration of therapy is determined by pertinent literature and clinical practice guidelines for the condition being treated. Monitor closely for worsening of depression and suicidal behavior or thinking, especially during initiation of therapy and during dose changes. Monitor for side effects of the antidepressant; some of these effects can increase the risk of falls. Review for continued need of the antidepressant at least quarterly and document 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. Before discontinuation, many antidepressants, including SNRIs such as desvenlafaxine, need a taper to avoid a withdrawal/discontinuation syndrome.[60742]

    Laboratory test interference

    Some reports suggest that a laboratory test interference, with 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.

    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
    cardiomyopathy / 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 / 22.0-27.0
    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
    akathisia / Delayed / Incidence not known
    hallucinations / Early / Incidence not known
    hostility / Early / Incidence not known
    depression / 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 / 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
    restlessness / Early / 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; Aspirin: (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; Aspirin; Diphenhydramine: (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; Dihydrocodeine: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of dihydrocodeine and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue dihydrocodeine if serotonin syndrome is suspected. Additionally, concomitant use of dihydrocodeine with desvenlafaxine may decrease dihydrocodeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of dihydrocodeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease dihydrocodeine plasma concentrations and increase dihydromorphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Dihydrocodeine is primarily metabolized by CYP2D6 to dihydromorphine, and by CYP3A4. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Acetaminophen; Dextromethorphan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Acetaminophen; Hydrocodone: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Acetaminophen; 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.
    Acetaminophen; Oxycodone: (Moderate) If concomitant use of oxycodone and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    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.
    Alfentanil: (Moderate) If concomitant use of alfentanil and desvenlafaxine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Almotriptan: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Alteplase: (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.
    Amlodipine; 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.
    Amphetamine; Dextroamphetamine Salts: (Moderate) Coadministration of amphetamines with serotonin norepinephrine reuptake inhibitors (SNRIs) may increase the risk of serotonin syndrome. At high doses, amphetamines can increase serotonin release and act as serotonin agonists. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly during treatment initiation and dose increases. If serotonin syndrome occurs, serotonergic drugs should be discontinued and appropriate medical 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.
    Antithrombin III: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like antithrombin III. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Apixaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like apixaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Argatroban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like argatroban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    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) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6. (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: (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; Orphenadrine: (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) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6. (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; Citric Acid; Sodium Bicarbonate: (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) If concomitant use of oxycodone and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. (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: (Contraindicated) 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.
    Benzhydrocodone; Acetaminophen: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of benzhydrocodone and desvenlafaxine because of the potential risk of serotonin syndrome. Discontinue benzhydrocodone if serotonin syndrome is suspected. 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.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Contraindicated) 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: (Moderate) Serotonin syndrome may occur during coadministration of serotonergic drugs such as amphetamines and serotonin norepinephrine reuptake inhibitors. At high doses, amphetamines can increase serotonin release, as well as act as serotonin agonists. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly after a dose increase or the addition of other serotonergic medications to an existing regimen. Discontinue all serotonergic agents if serotonin syndrome occurs and implement appropriate medical management.
    Betrixaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like betrixaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    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.
    Bivalirudin: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like bivalirudin. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Brompheniramine; Dextromethorphan; Guaifenesin: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Bupivacaine; 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.
    Buprenorphine: (Moderate) 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. 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: (Moderate) 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. 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: (Moderate) Coadministration of buspirone with serotonin norepinephrine reuptake inhibitors (SNRIs) may increase the risk of serotonin syndrome. Both types of medications have serotonergic properties. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly during treatment initiation and dose increases. If serotonin syndrome occurs, all serotonergic drugs should be discontinued and appropriate medical treatment should be initiated.
    Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Capsaicin; Metaxalone: (Moderate) Concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and metaxalone may increase the risk for serotonin syndrome. Monitor patients for serotonin syndrome if concomitant use is necessary.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    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.
    Celecoxib; 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. (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.
    Chlordiazepoxide; 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.
    Chlorpheniramine; Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Chlorpheniramine; Dextromethorphan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of dihydrocodeine and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue dihydrocodeine if serotonin syndrome is suspected. Additionally, concomitant use of dihydrocodeine with desvenlafaxine may decrease dihydrocodeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of dihydrocodeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease dihydrocodeine plasma concentrations and increase dihydromorphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Dihydrocodeine is primarily metabolized by CYP2D6 to dihydromorphine, and by CYP3A4. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Chlorpheniramine; Hydrocodone: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Chlorpheniramine; 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.
    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) Carefully monitor patients for signs and symptoms of bleeding during coadministration of desvenlafaxine and clopidogrel. Serotonin-norepinephrine reuptake inhibitors (SNRIs) affect platelet activation; therefore, concomitant use may increase the risk of bleeding.
    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.
    Cocaine: (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 cocaine. 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.
    Codeine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Codeine; Guaifenesin: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Codeine; Phenylephrine; Promethazine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Codeine; Promethazine: (Moderate) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of codeine and desvenlafaxine because of the potential risk of serotonin syndrome and decreased codeine efficacy. Discontinue codeine if serotonin syndrome is suspected. Additionally, concomitant use of codeine with desvenlafaxine may decrease codeine plasma concentrations resulting in reduced efficacy or symptoms of opioid withdrawal. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage increase of codeine until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease codeine plasma concentrations and increase morphine plasma concentrations resulting in prolonged opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Codeine is primarily metabolized by CYP2D6 to morphine, and by CYP3A4 to norcodeine; norcodeine does not have analgesic properties. Desvenlafaxine is a weak inhibitor of 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.
    Dabigatran: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like dabigatran. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Dalteparin: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like dalteparin. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    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.
    Darunavir; Cobicistat; 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.
    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.
    Desirudin: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like desirudin. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan; Bupropion: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan; Guaifenesin: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan; Guaifenesin; Potassium Guaiacolsulfonate: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    Dextromethorphan; Quinidine: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    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) Monitor for signs and symptoms of hyponatremia during concomitant diuretic and serotonin norepinephrine reuptake inhibitor (SNRI) use; consider discontinuing the SNRI if symptomatic hyponatremia occurs and institute appropriate medical intervention. Concomitant use increases the risk for developing 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: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, coadministration of desvenlafaxine and duloxetine should be avoided. Also, because both desvenlafaxine and duloxetine are serotonin norepinephrine reuptake inhibitors (SNRIs), coadministration is considered duplicative therapy. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Edoxaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like edoxaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Eletriptan: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Eliglustat: (Moderate) In extensive CYP2D6 metabolizers (EM) with mild hepatic impairment, coadministration of desvenlafaxine and eliglustat requires dosage reduction of eliglustat to 84 mg PO once daily. Desvenlafaxine is a weak CYP2D6 inhibitor; eliglustat is a CYP3A and CYP2D6 substrate. Coadministration with CYP2D6 inhibitors, such as desvenlafaxine, may increase eliglustat exposure and the risk of serious adverse events (e.g., QT prolongation and cardiac arrhythmias).
    Elvitegravir; Cobicistat; 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.
    Elvitegravir; Cobicistat; 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.
    Enoxaparin: (Major) Whenever possible, discontinue agents which may enhance the risk of hemorrhage, including serotonin norepinephrine reuptake inhibitors (SNRIs), before initiation of enoxaparin therapy. If coadministration is essential, conduct close clinical and laboratory monitoring.
    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: (Moderate) Because of the potential risk and severity of serotonin syndrome, use caution when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties, such as the ergot alkaloids. Weakness, hyperreflexia, and incoordination have been reported rarely when ergot alkaloids or other serotonin agonists have been coadministered with serotonin reuptake inhibitors, which may be indicative of serotonin excess. Inform patients of the potential risk and monitor for serotonin syndrome. If serotonin syndrome occurs, discontinue the offending agents and institute appropriate treatment.
    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.
    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.
    Fenfluramine: (Moderate) Use fenfluramine and serotonin norepinephrine reuptake inhibitors with caution due to an increased risk of serotonin syndrome. Monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    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, caution should be observed when coadministering drugs that have serotonergic properties such as desvenlafaxine and fentanyl. 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, all serotonergic agents should be discontinued and appropriate medical treatment should be initiated.
    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.
    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.
    Fondaparinux: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like fondaparinux. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Frovatriptan: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    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.
    Guaifenesin; Hydrocodone: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6.
    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.
    Heparin: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like heparin. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Homatropine; Hydrocodone: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Hydrocodone: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Hydrocodone; Ibuprofen: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6. (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.
    Hydrocodone; Pseudoephedrine: (Major) Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of hydrocodone and desvenlafaxine because of the potential risk of 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. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Discontinue hydrocodone if serotonin syndrome is suspected. Additionally, concomitant use of hydrocodone with desvenlafaxine may increase hydrocodone plasma concentrations and prolong opioid adverse reactions, including hypotension, respiratory depression, profound sedation, coma, and death. If coadministration is necessary, monitor patients closely at frequent intervals and consider a dosage reduction of hydrocodone until stable drug effects are achieved. Discontinuation of desvenlafaxine could decrease hydrocodone plasma concentrations, decrease opioid efficacy, and potentially lead to a withdrawal syndrome in those with physical dependence to hydrocodone. If desvenlafaxine is discontinued, monitor the patient carefully and consider increasing the opioid dosage if appropriate. Hydrocodone is a substrate for CYP2D6. Desvenlafaxine is a weak inhibitor of CYP2D6.
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Contraindicated) 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; Famotidine: (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) If concomitant use of oxycodone and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. (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.
    Iobenguane I 131: (Major) Discontinue serotonin norepinephrine reuptake inhibitors for at least 5 half-lives before the administration of the dosimetry dose or a therapeutic dose of iobenguane I-131. Do not restart serotonin norepinephrine reuptake inhibitors until at least 7 days after each iobenguane I-131 dose. Drugs that reduce catecholamine uptake or deplete catecholamine stores, such as serotonin norepinephrine reuptake inhibitors, may interfere with iobenguane I-131 uptake into cells and interfere with dosimetry calculations resulting in altered iobenguane I-131 efficacy.
    Isoniazid, INH: (Moderate) Due to the risk of serotonin syndrome, concurrent use of desvenlafaxine and medications with MAO-like activity, such as isoniazid, INH, should be approached with caution. 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 (SNRIs). If serotonin syndrome is suspected, duloxetine and concurrent serotonergic agents should be discontinued.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Moderate) Due to the risk of serotonin syndrome, concurrent use of desvenlafaxine and medications with MAO-like activity, such as isoniazid, INH, should be approached with caution. 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 (SNRIs). If serotonin syndrome is suspected, duloxetine and concurrent serotonergic agents should be discontinued.
    Isoniazid, INH; Rifampin: (Moderate) Due to the risk of serotonin syndrome, concurrent use of desvenlafaxine and medications with MAO-like activity, such as isoniazid, INH, should be approached with caution. 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 (SNRIs). If serotonin syndrome is suspected, duloxetine and concurrent serotonergic agents should be discontinued.
    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.
    Lasmiditan: (Moderate) Serotonin syndrome may occur during coadministration of lasmiditan and serotonin norepinephrine reuptake inhibitors. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome, particularly after a dose increase or the addition of other serotonergic medications to an existing regimen. Discontinue all serotonergic agents if serotonin syndrome occurs and implement appropriate medical management.
    Lepirudin: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like lepirudin. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Levomilnacipran: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, coadministration of desvenlafaxine and levomilnacipran should be avoided. Also, because both desvenlafaxine and levomilnacipran are serotonin norepinephrine reuptake inhibitors (SNRIs), coadministration is considered duplicative therapy. It is advisable to monitor for signs and symptoms of serotonin syndrome during an overlapping transition from one SNRI to another SNRI.
    Linezolid: (Contraindicated) 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) Initiate with lower doses and monitor patients for signs and symptoms of serotonin syndrome, particularly during treatment initiation or dosage increase, during concomitant lisdexamfetamine and serotonin norepinephrine reuptake inhibitor use. If serotonin syndrome occurs, discontinue therapy. Concomitant use increases the risk of serotonin syndrome.
    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.
    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: (Moderate) If concomitant use of meperidine and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Meperidine; Promethazine: (Moderate) If concomitant use of meperidine and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Metaxalone: (Moderate) Concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and metaxalone may increase the risk for serotonin syndrome. Monitor patients for serotonin syndrome if concomitant use is necessary.
    Methamphetamine: (Moderate) Serotonin syndrome may occur during coadministration of serotonergic drugs such as methamphetamine and serotonin norepinephrine reuptake inhibitors. At high doses, amphetamines can increase serotonin release, as well as act as serotonin agonists. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly after a dose increase or the addition of other serotonergic medications to an existing regimen. Discontinue all serotonergic agents if serotonin syndrome occurs and implement appropriate medical management.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Contraindicated) 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.
    Methenamine; Sodium 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.
    Methylene Blue: (Contraindicated) 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 Derivatives: (Moderate) Caution should be observed when coadministering methylphenidate derivatives and serotonin norepinephrine reuptake inhibitors (SNRIs). There are postmarketing reports of serotonin syndrome during concurrent use of methylphenidate derivatives with other serotonergic medications. There is also a case of a neuroleptic malignant syndrome-like reaction occurring in a child on chronic methylphenidate therapy after ingesting methylphenidate with an SNRI. It is unclear if the reaction was the result of a drug interaction. Monitor patients for the emergence of serotonin syndrome. If serotonin syndrome occurs, serotonergic agents should be discontinued and appropriate medical management should be implemented.
    Metoclopramide: (Moderate) Concomitant use of metoclopramide and serotonin and norepinephrine reuptake inhibitors (SNRIs) may increase the risk for serotonin syndrome. Monitor patients for serotonin syndrome if concomitant use is necessary. In rare cases postmarketing, NMS-like symptoms, which may overlap with serotonin syndrome symptoms, have been reported with metoclopramide when used with serotonergic agents.
    Metoprolol: (Moderate) Decrease the metoprolol dose by up to one-half when coadministered with desvenlafaxine 400 mg/day; resume original metoprolol dose if desvenlafaxine 400 mg/day is discontinued. No dosage adjustment is necessary when metoprolol is coadministered with desvenlafaxine 100 mg/day or lower. Monitor for increased metoprolol adverse reactions including bradycardia and hypotension during coadministration as metoprolol exposure may be increased. Clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 at doses of 100 mg/day; however, at desvenlafaxine doses of 400 mg/day, there is a weak inhibitory effect on CYP2D6.
    Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Decrease the metoprolol dose by up to one-half when coadministered with desvenlafaxine 400 mg/day; resume original metoprolol dose if desvenlafaxine 400 mg/day is discontinued. No dosage adjustment is necessary when metoprolol is coadministered with desvenlafaxine 100 mg/day or lower. Monitor for increased metoprolol adverse reactions including bradycardia and hypotension during coadministration as metoprolol exposure may be increased. Clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 at doses of 100 mg/day; however, at desvenlafaxine doses of 400 mg/day, there is a weak inhibitory effect on CYP2D6.
    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: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, coadministration of desvenlafaxine and milnacipran should be avoided. Also, because both desvenlafaxine and milnacipran are serotonin norepinephrine reuptake inhibitors (SNRIs), coadministration is considered duplicative therapy. 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: (Contraindicated) 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 milnacipran or within 7 days of discontinuing treatment with other SNRIs. Conversely, SNRIs should not be initiated within 14 days of stopping an MAOI. Monitor the patient for serotonin-related effects during therapy transitions.
    Morphine: (Moderate) If concomitant use of morphine and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Morphine; Naltrexone: (Moderate) If concomitant use of morphine and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    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; Esomeprazole: (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.
    Naratriptan: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    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, Fosnetupitant; 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.
    Olanzapine; 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.
    Oliceridine: (Moderate) If concomitant use of oliceridine and desvenlafaxine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    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.
    Oxycodone: (Moderate) If concomitant use of oxycodone and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Oxymorphone: (Moderate) If concomitant use of oxymorphone and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Ozanimod: (Major) Coadministration of ozanimod with desvenlafaxine is not recommended due to the potential for hypertensive crisis. If coadministration is necessary, closely monitor patients for hypertension and serotonergic effects. An active metabolite of ozanimod inhibits MAO-B, which may increase the potential for hypertensive crisis. Desvenlafaxine may increase blood pressure by increasing serotonin and norepinephrine concentrations.
    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: (Moderate) Monitor patients for an increase in paroxetine-related adverse reactions and signs and symptoms of serotonin syndrome during concomitant use of paroxetine and desvenlafaxine, particularly during treatment initiation and dosage increases. If serotonin syndrome occurs, consider discontinuation of therapy. The concomitant use of serotonergic drugs increases the risk of serotonin syndrome. Concomitant use may increase paroxetine exposure. Paroxetine is a CYP2D6 substrate and desvenlafaxine is a weak CYP2D6 inhibitor at doses of 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.
    Pentosan: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and pentosan, which has weak anticoagulant properties. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    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 serotonin norepinephrine reuptake inhibitors (SNRIs) together with caution due to a potential for serotonin syndrome. Monitor weight, cardiovascular status, and for potential serotonergic adverse effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome when combined with serotonergic agents. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses and some large controlled clinical studies have allowed patients to start phentermine-based therapy for obesity along with their SNRI as long as the antidepressant dose had been stable for at least 3 months prior. Such therapy was generally well-tolerated, especially at lower phentermine doses. Because depression and obesity often coexist, the study data may be important to providing optimal co-therapies.
    Phentermine; Topiramate: (Moderate) Use phentermine and serotonin norepinephrine reuptake inhibitors (SNRIs) together with caution due to a potential for serotonin syndrome. Monitor weight, cardiovascular status, and for potential serotonergic adverse effects. Phentermine is related to the amphetamines, and there has been historical concern that phentermine might exhibit potential to cause serotonin syndrome when combined with serotonergic agents. However, recent data suggest that phentermine's effect on MAO inhibition and serotonin augmentation is minimal at therapeutic doses and some large controlled clinical studies have allowed patients to start phentermine-based therapy for obesity along with their SNRI as long as the antidepressant dose had been stable for at least 3 months prior. Such therapy was generally well-tolerated, especially at lower phentermine doses. Because depression and obesity often coexist, the study data may be important to providing optimal co-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.
    Promethazine; Dextromethorphan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering dextromethorphan with desvenlafaxine. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. In addition, the manufacturer of desvenlafaxine recommends that the dose of CYP2D6 substrates, such as dextromethorphan, be reduced by up to 50% if used with desvenlafaxine 400 mg/day, a CYP2D6 inhibitor.
    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.
    Propranolol; Hydrochlorothiazide, HCTZ: (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) If concomitant use of remifentanil and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    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.
    Rivaroxaban: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of serotonin norepinephrine reuptake inhibitors (SNRIs) and anticoagulants like rivaroxaban. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Rizatriptan: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Safinamide: (Contraindicated) 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.
    Selegiline: (Contraindicated) Serotonin norepinephrine reuptake inhibitors (SNRIs) are contraindicated for use with selegiline, a selective monoamine oxidase type B inhibitor (MAO-B inhibitor). At least 14 days should elapse between discontinuation of selegiline and initiation of treatment with an SNRI. After stopping treatment with an SNRI, a time period equal to 4 to 5 half-lives of the SNRI or any active metabolite should elapse before starting therapy with selegiline. Serotonin syndrome has occurred in patients receiving selective MAO-B inhibitors and serotonin-augmenting antidepressants simultaneously. Monitor for serotonergic side effects during therapy transitions.
    Serotonin-Receptor Agonists: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    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.
    Solriamfetol: (Moderate) Monitor blood pressure and heart rate during coadministration of solriamfetol, a norepinephrine and dopamine reuptake inhibitor, and antidepressants that are serotonin norepinephrine reuptake inhibitors. Concurrent use of solriamfetol and other medications that increase blood pressure and/or heart rate may increase the risk of such effects. Coadministration of solriamfetol with other drugs that increase blood pressure or heart rate has not been evaluated.
    St. John's Wort, Hypericum perforatum: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when coadministering St. John's wort and serotonin norepinephrine reuptake inhibitors (SNRIs). Inform the patient of the increased risk and monitor for the emergence of serotonin syndrome, particularly at treatment initiation or with dose increases. If serotonin syndrome occurs, serotonergic agents should be discontinued and appropriate medical treatment should be initiated.
    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: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Sumatriptan; Naproxen: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. (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.
    Tapentadol: (Moderate) If concomitant use of tapentadol and serotonin norepinephrine reuptake inhibitors is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    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: (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) Desvenlafaxine is a mild inhibitor of CYP2D6 at a dose of 400 mg/day and the use of thioridazine concomitantly with CYP2D6 inhibitors is contraindicated due to the possible risk of QT prolongation and subsequent arrhythmias, or other serious side effects, occurring from elevated serum concentrations of thioridazine.
    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.
    Tramadol; Acetaminophen: (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: (Moderate) Coadministration of trazodone and desvenlafaxine may increase the risk of serotonin syndrome. Serotonin syndrome has been reported with both drugs when taken alone, but especially when coadministered with other serotonergic agents. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome. Discontinue desvenlafaxine and trazodone and initiate symptomatic treatment if serotonin syndrome occurs.
    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.
    Tryptophan, 5-Hydroxytryptophan: (Major) The manufacturer of desvenlafaxine recommends caution during concurrent use of tryptophan. Since tryptophan is converted to serotonin (5-hydroxytryptamine), the use of tryptophan in patients receiving desvenlafaxine could lead to central serotonin excess and 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. If serotonin syndrome occurs, all serotonergic agents should be discontinued and appropriate medical treatment should be initiated.
    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: (Major) Due to similarity of pharmacology and the potential for additive adverse effects, including serotonin syndrome, coadministration of venlafaxine and desvenlafaxine should be avoided. Also, because desvenlafaxine is the active metabolite of venlafaxine and both agents are serotonin norepinephrine reuptake inhibitors (SNRIs), coadministration is considered duplicative therapy. 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.
    Warfarin: (Moderate) Advise patients of the increased bleeding risk associated with the concomitant use of desvenlafaxine and warfarin. Carefully monitor patients receiving warfarin therapy if desvenlafaxine is initiated or discontinued. Case reports and epidemiological studies have demonstrated an association between use of drugs that interfere with serotonin reuptake and gastrointestinal bleeding.
    Zolmitriptan: (Moderate) 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 serotonin-receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan). Serotonin syndrome has been reported during concurrent use of serotonin-receptor agonists and serotonin norepinephrine reuptake inhibitors. Some patients had used the combination previously without incident when serotonin syndrome occurred. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose increases. Discontinue serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    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

    There are no adequate and well-controlled studies regarding the use of desvenlafaxine during human pregnancy; however, epidemiologic studies of venlafaxine, the parent compound of desvenlafaxine, have not shown a clear association with adverse developmental outcomes when used during pregnancy. In animal studies, there were no teratogenic effects at doses of desvenlafaxine above the maximum recommended human dose; however, other fetal complications were observed. Consider the risks of untreated depression during pregnancy as well as the potential fetal risks. When treating a pregnant individual with a serotonin norepinephrine reuptake inhibitor (SNRI) or other serotonergic agent during the third trimester, neonatal discontinuation symptoms may occur 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 obstetric delivery; symptoms have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor, jitteriness, irritability, and constant crying. These features are consistent with serotonin syndrome or a drug discontinuation syndrome. In terms of maternal risk, exposure to SNRIs in mid to late pregnancy may increase the risk of eclampsia and use near obstetric delivery may increase the risk for postpartum hemorrhage. If clinically feasible, gradual tapering of the medication prior to delivery may be considered. The National Pregnancy Registry for Antidepressants is dedicated to evaluating the safety of antidepressant medications that may be taken during pregnancy to treat a wide range of mood, anxiety, or psychiatric disorders. The pregnancy registry monitors pregnancy outcomes; information about the registry can be obtained at https://womensmentalhealth.org/research/pregnancyregistry/antidepressants/ or by calling 1-866-961-2388.

    MECHANISM OF ACTION

    Desvenlafaxine is a serotonin norepinephrine reuptake inhibitor (SNRI) antidepressant thought to exert its therapeutic effects in part by inhibiting the central reuptake of serotonin and norepinephrine. Because of the delay in therapeutic response, it is theorized that long-term neurotransmitter receptor modulation is an important mechanism of effect. Desvenlafaxine has a 10-fold higher affinity for the reuptake inhibition of serotonin compared to norepinephrine. All SNRIs inhibit serotonin uptake in human platelets, which has been associated with an increased risk of bleeding events. In addition, SNRIs can increase blood pressure and heart rate; cases of elevated blood pressure requiring immediate treatment have been reported. Desvenlafaxine does not have significant affinity for histaminergic, muscarinic, or alpha-1 adrenergic receptors and does not inhibit monoamine oxidase. In a thorough QTc study, desvenlafaxine did not cause QT prolongation.

    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.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. Desvenlafaxine is primarily metabolized by conjugation (mediated by UGT isoforms) and, to a minor extent, through oxidative metabolism. CYP3A4 is the cytochrome P450 isozyme mediating the oxidative metabolism (N-demethylation) of desvenlafaxine. The elimination half-life is 11 hours.
     
    Affected cytochrome P450 (CYP450) isoenzymes and drug transporters: CYP2D6
    Clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 metabolism at the dose of 100 mg daily; however, if the dose is increased to 400 mg/day, then desvenlafaxine may increase concentrations and exposure of drugs metabolized by CYP2D6. No dosage adjustment of primary substrates of CYP2D6 is needed 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 (50%) if coadministered with desvenlafaxine 400 mg/day.