For the past week, Wyeth has been on the defensive over Pristiq. Instead of approving the drug as a salve for hot flashes suffered by menopausal women, the agency issued only an approvable letter. The FDA did the same thing when it came to depression earlier this year. So Wall Street is understandably concerned - will this drug ever get approved?

To quell the speculation, Wyeth’s chief scientist, Bob Ruffalo, and chief medical officer, Gary Stiles, spent nearly an hour late this afternoon explaining in slightly greater detail their view of cardiovascular and liver side-effect issues that worry the FDA. Bottom line, says Ruffalo, is that Wyeth believes Pristiq doesn’t present a safety risk. “The safety profile is sound,” says Stiles.

Nonetheless, the agency wants a new, year-long trial, which won’t wrap up until the end of 2008. That’s a big delay. And there’s still no assurance Pristiq will get approved for hot flashes. Meanwhile, Ruffalo says he’s “confident” Pristiq will be approved for depression early next year. They need to be right: the Effexor antidepressant is far and away Wyeth’s biggest seller - last year, sales were $3.7 billion - but the patent expires in 2010.