Wyeth has presented some promising new late-stage data for Pristiq, the firm’s experimental antidepressant.

The data is from two Phase III clinical studies of Pristiq (desvenlafaxine), an investigational serotonin-norepinephrine reuptake inhibitor, which showed that adults who received a 50mg/day dose of the drug for the treatment of major depressive disorder experienced a statistically significant reduction in symptoms compared to placebo.

In both studies, the firm said that discontinuation rates due to adverse events for Pristiq 50mg/day were similar to placebo. Also the rates of discontinuation due to AEs for placebo and Pristiq 100mg/day were 3% and 7%, respectively.

Wyeth will be hoping that this latest data will help to get approval of the treatment, which has had something of a tough time with US regulators. In August, the firm submitted the results of two studies that the Food and Drug Administration had asked for when it issued only an approvable letter for Pristiq in January.

The FDA is expected to make a decision on Pristiq during the first quarter of 2008. The drug is a follow-up to the blockbuster Effexor (venlafaxine) and if Pristiq reaches the market, its sales should compensate for the loss of earnings once the extended-release version of Effexor faces generic competition in 2010.