"The company's disclosure of this regulatory update should not be interpreted to mean that the potential for FDA approval of Qnexa has improved."
-- Peter Tam, president of VIVUS (Nasdaq: VVUS)

Investors aren't buying it. And neither am I. And I doubt the company is all that upset about the 13% pop shares saw this morning.

In fact, I doubt Peter Tam or anyone else at VIVUS believes the potential for approval hasn't gone up. The warning is clearly there to cover VIVUS in case the Food and Drug Administration doesn't approve its obesity drug. In an unusual move, the company even put the warning in the main section, instead of in the Safe Harbor Statement at the end. Call it double-covered, I guess.

The regulatory update let investors know that the FDA asked VIVUS to remove the contraindication for women of childbearing potential from the proposed label. You'll recall that back in September, VIVUS said that it had reached an agreement with the agency to seek approval just for men and women without childbearing potential. The new request will add back women who aren't pregnant but could become pregnant, increasing the potential market substantially.

More importantly -- contrary to the warning in the press release -- the change is a sign that the FDA might be lightening up on the high risk-to-benefit standard it has been holding obesity drugs to. Topiramate, one of the ingredients in Qnexa, has been linked to birth defects. It's the active ingredient in Johnson & Johnson's (NYSE: JNJ) Topamax -- that's where the link was discovered -- but Topamax is approved for treating seizures, so there's a more lenient risk-benefit analysis than there is for an obesity drug.

Adding back younger women that could become pregnant also makes VIVUS' data package stronger. There were women in the clinical trials for Qnexa -- substantially more women than men, in fact -- and with an average age of 43 in one of the trials, many were likely of childbearing potential. There was potential that the FDA might balk at approving the drug for a population that it wasn't exclusively tested on, but the new label essentially eliminates that risk.

If the agency is really lightening up, that's good news for not only VIVUS, but also Arena Pharmaceuticals (Nasdaq: ARNA) and Orexigen Therapeutics (Nasdaq: OREX), which are both hoping to get approved on their second attempt. Arena recently resubmitted its marketing application for lorcaserin. Orexigen will be awhile since it has to run another clinical trial, but at least the FDA seems to be lightening up there, too, having reduced the size of the trial.

All three obesity drugmakers are only appropriate for the most risk-tolerant investor. Approvals are far from a guarantee; that warning is there for a reason. But there's no doubt that the potential for approval has increased.

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