Serious Drug Interactions
Monoamine Oxidase Inhibitors: See CONTRAINDICATIONS, and Drug-Drug interactions below.
Selected drug interaction studies were performed. The combination of linear pharmacokinetics, a simple metabolic profile without the potential for CYP polymorphism factors, weak interactions with selected probe substrates, and low protein binding results in a low potential for the interaction of desvenlafaxine with other prescribed medications.
Monoamine Oxidase Inhibitors
Desvenlafaxine succinate is contraindicated in patients taking MAOIs. Desvenlafaxine succinate must not be used in combination with a monoamine oxidase inhibitor (MAOI), or within at least 14 days of discontinuing treatment with an MAOI. Based on the half-life of desvenlafaxine succinate, at least 7 days should be allowed after stopping desvenlafaxine succinate before starting an MAOI (see CONTRAINDICATIONS).
As with other serotonergic agents, serotonin syndrome, a potentially life-threatening condition, may occur with desvenlafaxine treatment, particularly with concomitant use of other agents that may affect the serotonergic neurotransmitter system (including triptans, SSRIs, other SNRIs, amphetamines, lithium, sibutramine, fentanyl and its analogues, dextromethorphan, tramadol, tapentadol, meperidine, methadone and pentazocine or St. John's Wort [Hypericum perforatum], with drugs which impair metabolism of serotonin (such as MAOIs, including linezolid [an antibiotic which is a reversible non-selective MAOI], and methylene blue; see CONTRAINDICATIONS), or with serotonin precursors (such as tryptophan supplements). Serotonin syndrome symptoms may include mental status changes, autonomic instability, neuromuscular aberrations and/or gastrointestinal symptoms (see WARNINGS AND PRECAUTIONS).
If concomitant treatment of desvenlafaxine with an SSRI, an SNRI or a 5-hydroxytryptamine receptor agonist (triptan) is clinically warranted, careful observation of the patient is advised, particularly during treatment initiation and dose increases. The concomitant use of desvenlafaxine with serotonin precursors (such as tryptophan supplements) is not recommended.
Central Nervous System (CNS) Active Agents
The risk of using desvenlafaxine succinate in combination with other CNS-active drugs has not been systematically evaluated. Consequently, caution is advised when desvenlafaxine succinate is taken in combination with other CNS-active drugs.
Drugs Affecting Platelet Function (e.g., NSAIDs, ASA, and other anticoagulants)
Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies of the case-control and cohort design that have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding have also shown that concurrent use of an NSAID, ASA or other anticoagulants may potentiate this risk of bleeding.
Altered anticoagulant effects, including increased bleeding, have been reported when SSRIs or SNRIs are co-administered with warfarin. Patients receiving warfarin therapy should be carefully monitored when PRISTIQ is initiated or discontinued (see WARNINGS AND PRECAUTIONS, Hematologic, Abnormal Bleeding).
Potential for other drugs to affect desvenlafaxine succinate (see also ACTION AND CLINICAL PHARMACOLOGY)
Inhibitors of CYP3A4
CYP3A4 is a minor pathway for the metabolism of PRISTIQ. In a clinical study, ketoconazole (200 mg BID) increased the area under the concentration vs. time curve AUC of PRISTIQ (400 mg single dose) by about 43% and Cmax by about 8%. Concomitant use of PRISTIQ with potent inhibitors of CYP3A4 may result in higher concentrations of PRISTIQ.
Inhibitors of other CYP enzymes
Based on in vitro data, drugs that inhibit CYP isozymes 1A1, 1A2, 2A6, 2D6, 2C8, 2C9, 2C19, and 2E1 are not expected to have significant impact on the pharmacokinetic profile of desvenlafaxine.
Potential for desvenlafaxine to affect other drugs (see also ACTION AND CLINICAL PHARMACOLOGY)
Drugs metabolized by CYP2D6
Clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 metabolism at the dose of 100 mg daily. When desvenlafaxine succinate was administered at a dose of 100 mg daily in conjunction with a single 50 mg dose of desipramine, a CYP2D6 substrate, the AUC of desipramine increased approximately 17%. When 400 mg of desvenlafaxine was administered (8 times the recommended 50 mg dose), the AUC of desipramine increased approximately 90%. When desvenlafaxine succinate was administered at a dose of 100 mg daily in conjunction with a single 60 mg dose of codeine, a CYP2D6 substrate metabolized to morphine, the AUC of codeine was unchanged, the AUC of morphine decreased approximately 8%. Concomitant use of desvenlafaxine with a drug metabolized by CYP2D6 may result in increased concentrations of that drug and decreased concentrations of its CYP2D6 metabolites.
Drugs metabolized by CYP3A4
In vitro, desvenlafaxine does not inhibit or induce the CYP3A4 isozyme. In a clinical study, desvenlafaxine (400 mg daily) was co-administered with a single 4 mg dose of midazolam (a CYP3A4 substrate). The AUC and Cmax of midazolam decreased by approximately 31% and 16%, respectively. In a second study, desvenlafaxine 50 mg daily was co-administered with a single 4 mg dose of midazolam. The AUC and Cmax of midazolam decreased by approximately 29% and 14%, respectively. Concomitant use of desvenlafaxine with a drug metabolized by CYP3A4 may result in lower exposure to that drug.
Drugs metabolized by a combination of both CYP2D6 and CYP3A4
Clinical studies with aripiprazole and tamoxifen suggest that desvenlafaxine at twice the recommended dose (100 mg daily) does not have a clinically relevant effect on drugs metabolized by a combination of both CYP2D6 and CYP3A4 enzymes.
Desvenlafaxine succinate was studied at a dose of 100 mg daily in conjunction with a single 5 mg dose of aripiprazole, a CYP2D6 and CYP3A4 substrate metabolized to the active metabolite dehydroaripiprazole.
A single 40 mg dose of tamoxifen, which is metabolized to active metabolites 4-hydroxy-tamoxifen and endoxifen by CYP2D6 and CYP3A4, was also studied in conjunction with desvenlafaxine succinate (100 mg daily).
Drugs metabolized by CYP1A2, 2A6, 2C8, 2C9 and 2C19
In vitro, desvenlafaxine does not inhibit CYP1A2, 2A6, 2C8, 2C9, and 2C19 isozymes and would not be expected to affect the pharmacokinetics of drugs that are metabolized by these CYP isozymes.
There are no clinical data establishing the risks and/or benefits of electroconvulsive therapy combined with PRISTIQ treatment for MDD.
In vitro, desvenlafaxine is not a substrate or an inhibitor for the P-glycoprotein transporter. The pharmacokinetics of desvenlafaxine are unlikely to be affected by drugs that inhibit the P-glycoprotein transporter and desvenlafaxine is not likely to affect the pharmacokinetics of drugs that are substrates of the P-glycoprotein transporter.
Food does not alter the bioavailability of desvenlafaxine.
St. John’s Wort
In common with SSRI’s, pharmacodynamic interactions between PRISTIQ and the herbal remedy St. John’s Wort may occur and may result in an increase in undesirable effects (see DRUG INTERACTIONS, Serotonin Syndrome).
False positive urine immunoassay screening tests for phencyclidine (PCP) and amphetamine have been reported in patients taking PRISTIQ. This is due to lack of specificity of the screening tests. False positive test results may be expected for several days following discontinuation of PRISTIQ therapy. Confirmatory tests, such as gas chromatography/mass spectrometry, will distinguish PRISTIQ from PCP and amphetamine.
As with all CNS-active drugs, patients should be advised to avoid alcohol consumption while taking desvenlafaxine succinate.
Interference with Cognitive and Motor Performance
A clinical study that assessed the effects of desvenlafaxine on behavioral performance of healthy individuals did not reveal clinically significant impairment of psychomotor, cognitive, or complex behavior performance. However, since any CNS-active drug may impair judgment, thinking, or motor skills, patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that PRISTIQ therapy does not adversely affect their ability to engage in such activities.