FDA Delays Wyeth's Pristiq Over Side Effects

There's just no mystique in Pristiq. In a conference call this morning, Wyeth's exec vp and chief medical officer, Gary Stiles, says the FDA delayed Pristiq, which the drugmakers hope to sell to treat menopausal hot flashes, because the agency wants a new, one-year, randomized, placebo-controlled clinical trial after expressing concerns about cardiovascular and liver adverse events.

Stiles says side effects weren't "surprising to us. It was part of our package." Specifically, three women out of about 2,000 experienced elevated liver enzyme levels, which he says returned to normal after discontinuing the drug.

He also says women with high cardiovascular risk factors in one study experienced side effects. "We've looked at this multiple times in great depth, and we've come to the conclusion that we don't believe they were, in any way, caused by" Pristiq, Stiles says, although he wasn't more specific.

Despite the setback, Stiles says Wyeth remains committed to obtaining FDA approval to market Pristiq for hot flashes, and also doesn't expect the request for a new trial to affect a separate request for agency approval to sell the drug for depression. In January, the FDA issued an approvable letter for that indication, but didn't seek more trial data. "We will work with the agency, although we've not yet met with them" to discuss the newest setback, he says.

Stiles also maintained the delays aren't related to quality-control problems at a manufacturing plant in Puerto Rico, where Pristiq is made. The FDA cited the plant numerous times for deficiencies and only recently gave it a passing grade.

Update from Barbara Ryan, an analyst at Deutsche Bank Securities: "This blow to Pristiq will intensify the company's exposure to Effexor generics in 2010. In our view, the fact that Pristiq would be a "non-hormonal" treatment for (hot flashes) was the only visible commercial hook for this "me too" SNRI. For all intents and purposes, this indication is dead."

Pristiq wasn't setting the world on fire - pardon the pun - before this week, by the way. Two months ago, managed care and insurers reported not being impressed, in a note written by former Prudential Securities analyst Tim Anderson. He also foreshadowed this week's event's in another note in which he reiterated CV concerns. And Wall Street is still waiting for updated data on depression, given that a recent inadvertent disclosure showed Pristiq taking six weeks to work at low doses.