Medications: Pristiq^® – desvenlafaxine

PRISTIQ, is a serotonin and norepinephrine reuptake inhibitor (SNRI) indicated for the treatment of adults with major depressive disorder (MDD) (1).

DOSAGE AND ADMINISTRATION

• Recommended dose: 50 mg once daily with or without food (2.1).
• There was no evidence that doses greater than 50 mg per day confer any additional benefit (2.1).
• The 25 mg per day dose is intended for a gradual reduction in dose when discontinuing treatment or dosing in severe renal and end-stage renal disease patients (2.1).
• Discontinuation: Reduce dose gradually whenever possible (2.1).
• Take tablets whole; do not divide, crush, chew, or dissolve (2.1).
• Moderate renal impairment: Maximum dose 50 mg per day (2.2).
• Severe renal impairment and end-stage renal disease: Maximum dose 25 mg per day or 50 mg every other day (2.2).
• Moderate to severe hepatic impairment: Maximum dose 100 mg per day (2.3).

Most common adverse reactions (incidence ≥5% and twice the rate of placebo in the 50 or 100 mg dose groups) were: nausea, dizziness, insomnia, hyperhidrosis, constipation, somnolence, decreased appetite, anxiety, and specific male sexual function disorders (6.1).

• Hypersensitivity to desvenlafaxine succinate, venlafaxine hydrochloride or any excipients in the PRISTIQ formulation (4).
• Serotonin Syndrome and MAOIs: Do not use MAOIs intended to treat psychiatric disorders with PRISTIQ or within 7 days of stopping treatment with PRISTIQ. Do not use PRISTIQ within 14 days of stopping an MAOI intended to treat psychiatric disorders. In addition, do not start PRISTIQ in a patient who is being treated with linezolid or intravenous methylene blue (4).

WARNINGS AND PRECAUTIONS:

• Serotonin Syndrome: Increased risk when co-adminstered with other serotonergic agents (e.g., SSRI, SNRI, triptans), but also when taken alone. If it occurs, discontinue PRISTIQ and initiate supportive treatment (5.2).
• Elevated Blood Pressure: Control hypertension before initiating treatment. Monitor blood pressure regularly during treatment (5.3).
• Increased Risk of Bleeding: Concomitant use of aspirin, NSAIDs, other antiplatelet drugs, warfarin, and other anticoagulants may increase this risk (5.4).
• Angle Closure Glaucoma: Avoid use of antidepressants, including PRISTIQ, in patients with untreated anatomically narrow angles treated. (5.5)
• Activation of Mania/Hypomania: Use cautiously in patients with Bipolar Disorder. Caution patients about risk of activation of mania/hypomania (5.6).
• Discontinuation Syndrome: Taper dose when possible and monitor for discontinuation symptoms (5.7).
• Seizure: Can occur. Use cautiously in patients with seizure disorder (5.8).
• Hyponatremia: Can occur in association with SIADH (5.9).
• Interstitial Lung Disease and Eosinophilic Pneumonia: Can occur (5.10).

There is limited clinical trial experience with desvenlafaxine succinate overdosage in humans. However, desvenlafaxine (PRISTIQ) is the major active metabolite of venlafaxine. Overdose experience reported with venlafaxine (the parent drug of PRISTIQ) is presented below; the identical information can be found in the Overdosage section of the venlafaxine package insert. In postmarketing experience, overdose with venlafaxine (the parent drug of PRISTIQ) has occurred predominantly in combination with alcohol and/or other drugs. The most commonly reported events in overdosage include tachycardia, changes in level of consciousness (ranging from somnolence to coma), mydriasis, seizures, and vomiting. Electrocardiogram changes (e.g., prolongation of QT interval, bundle branch block, QRS prolongation), sinus and ventricular tachycardia, bradycardia, hypotension, rhabdomyolysis, vertigo, liver necrosis, serotonin syndrome, and death have been reported. Published retrospective studies report that venlafaxine overdosage may be associated with an increased risk of fatal outcomes compared to that observed with SSRI antidepressant products, but lower than that for tricyclic antidepressants. Epidemiological studies have shown that venlafaxine-treated patients have a higher pre-existing burden of suicide risk factors than SSRI-treated patients. The extent to which the finding of an increased risk of fatal outcomes can be attributed to the toxicity of venlafaxine in overdosage, as opposed to some characteristic(s) of venlafaxine-treated patients, is not clear.

Management of Overdosage: No specific antidotes for PRISTIQ are known. In managing over dosage, consider the possibility of multiple drug involvement. In case of overdose, call Poison Control Center at 1-800-222-1222 for latest recommendations.