It's not looking so great for the would-be "female Viagra," as Bloomberg News reports the FDA has rejected Sprout Pharmaceuticals' flibanserin pill. (Guess there's no need for a sexy brand name until you've bagged regulatory approval.) The agency just isn't convinced the "modest affect" of the drug outweighs potential side effects, which include fatigue and nausea.

Sprout is appealing the decision, though that's generally considered a long shot, and the company still insists on the drug's merits. According to Bloomberg News, they say that "in clinical trials, Sprout's pill almost doubled the increase women saw in satisfying sexual experiences over a month's time compared with patients who took a placebo."

"I think this could be a blockbuster drug," added CEO Cindy Whitehead. No kidding.

But this is actually the second rejection for the drug, and there were lot of doubters on the first go-round. Flibanserin was originally submitted by a German company, which sold the rights after a 2010 denial. And that's on top of failed efforts by other companies.

Problem is, low libido might be too complicated for a simple magic bullet.

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