The FDA is now requesting results from a one-year safety trial on how the drug affects these organs.
The decision stalls Wyeth’s plans to market Pristiq as the first non-hormonal drug for hot flushes and other menopause symptoms.
The US regulator’s concerns arose from trial data that showed elevated liver enzymes were found in three of 2,000 women taking the drug. The three women were taken off Pristiq and their enzymes returned to normal, the company said.
Wyeth said that these new safety concerns are unlikely to impact on the drug’s separate pending application as a depression treatment. Analysts, however, are doubting the drug’s future, according to Reuters. Even if it gets approval, which would be unlikely to happen until 2009 or 2010, its potential to ensure earnings growth after Wyeth’s Effexor patent lapses has been severely knocked.