Wyeth Pharmaceuticals, a division of Wyeth, said the US Food and Drug Administration (FDA) has approved Pristiq (desvenlafaxine), a structurally novel, once-daily serotonin-norepinephrine reuptake inhibitor (SNRI), to treat adult patients with major depressive disorder (MDD). Wyeth expects to begin shipping Pristiq to wholesalers beginning in the second quarter of 2008.

The FDA approval was subject to several post-marketing commitments, including conducting and submitting data from a new long-term maintenance (relapse prevention) study, a sexual dysfunction study, paediatric studies and a study exploring lower doses. The agency also requested an additional non-clinical toxicity study.

"We are pleased to be able to bring Pristiq to patients," said Bernard Poussot, president and chief executive officer, Wyeth. "Pristiq is Wyeth's fourth new drug to receive approval in the last twelve months, demonstrating our ability to achieve success through the rigorous scientific process of discovery and development. We look forward to working with FDA and other regulatory authorities around the world to continue to bring important new medicines to patients who need them."

The efficacy of Pristiq as a treatment for depression was established in four 8-week, randomized, double-blind, placebo-controlled, fixed-dose studies in adult outpatients who met the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for MDD. At the recommended dose of 50 mg, the discontinuation rate due to an adverse experience for Pristiq (4.1 per cent) was similar to the rate for placebo (3.8 per cent).

Side effects of many antidepressant therapies can cause some patients to stop taking their medication. The most commonly observed adverse reactions in patients taking Pristiq for MDD in short-term, fixed-dose studies (incidence >5 per cent and at least twice the rate of placebo in the 50 or 100 mg dose groups) were nausea, dizziness, insomnia, hyperhidrosis, constipation, somnolence (sleepiness), decreased appetite, anxiety, and specific male sexual function disorders.

Pristiq delivers the major active metabolite of Effexor XR (venlafaxine HCl) in its active state without going through the CYP2D6 metabolic pathway. This could be beneficial when Pristiq is coadministered with other commonly prescribed medications metabolized through that pathway. Effexor XR, discovered and developed by Wyeth, was the first SNRI approved by the FDA for MDD and is currently the most widely prescribed antidepressant in the world.

Pristiq, discovered and developed by Wyeth, demonstrates the company's significant and continued commitment to developing new therapies in the field of neuroscience.