Pristiq has been approved by the FDA to treat major depressive disorder

Tips to remember Pristiq

In May 2008, Wyeth will begin rolling out its new serotonin-norepinephrine reuptake inhibitor (SNRI), desvenlafaxine, the major active metabolite of the company's current extended-release blockbuster SNRI venlafaxine (Effexor XR), scheduled to go off patent shortly. The new drug, to be marketed as Pristiq, was approved by the Food & Drug Administration in February for the treatment of major depressive disorder.

In clinical studies, doses of 50 to 400 mg per day were shown to be effective, although no additional benefit was demonstrated at doses greater than 50 mg per day and adverse events and discontinuations were more frequent at higher doses. According to the prescribing information, patients with severe renal impairment and end-stage renal disease should take 50 mg every other day. Tablets should be taken at the same time each day and swallowed whole, not crushed or dissolved. When treatment is being discontinued, gradual dose reduction is recommended to minimize discontinuation symptoms. These symptoms occurred more often in patients who had a longer duration of therapy.

The label for desvenlafaxine includes the black box warning for antidepressants and the increased risk for suicidality. Patients should be monitored for clinical worsening and suicide risk while taking the drug. In addition, the label contains warnings for serotonin syndrome, activation of mania/hypomania, cholesterol and triglyceride elevation, interstitial lung disease and eosinophilic pneumonia, and mydriasis. Patients should be cautioned about the increased risk of bleeding associated with the concomitant use of desvenlafaxine with aspirin or other drugs that affect coagulation. Patients with narrow-angle glaucoma and cardiovascular disease should use desvenlafaxine with caution.

The most commonly observed adverse effects during clinical trials included nausea, dizziness, hyperhidrosis, insomnia, constipation, somnolence, male sexual dysfunction, and anxiety, among others.

Breden believes that patients who don't respond to venlafaxine at a low dose, but cannot tolerate its side effects at a high dose, may be candidates for desvenlafaxine.