Vivus Inc, hoping to bring to market the first new prescription diet drug in more than a decade, told U.S. medical advisers on Thursday that its weight-loss pill gives patients a safe option for shedding pounds and improving their health.

Vivus is seeking Food and Drug Administration support to sell its drug, Qnexa, to adults to use once a day, along with exercise and diet changes, to slim down. But first it must prove its pill dodges side effects that have sidelined past products.

The stakes are huge for Vivus and its investors, who have pushed the stock up more than 130 percent in the past year, drawn by the potential for huge sales to millions of overweight Americans. (

The FDA's panel of outside advisers will weigh Vivus' data before deciding later on Thursday whether to back the drug. The FDA will weigh the advisers' recommendation before making its final decision, expected by October 28.

FDA staff largely support the effectiveness of Qnexa, the first of three potential new diet drugs up for review this year. But they are concerned about its effect on fetuses, mental health and heart rate. Memory loss and other cognitive problems and body acid changes are also important issues.

That assessment, released in documents earlier this week, was cheered by investors who sent Vivus shares up nearly 20 percent, betting the safety concerns were not grave enough to keep Qnexa from pharmacy shelves. Trading in the shares was halted Thursday morning ahead of the FDA advisers' decision.

The medical need is urgent, said Louis Aronne, a medical professor at Weill-Cornell Medical College who addressed the advisers on behalf of Vivus. It's clear that we need new medical therapies to manage the epidemic of obesity.

If approved, Qnexa would offer a potential fat-fighting jump-start to the more than two-thirds of Americans who are overweight or obese -- and would boost a nearly 20-year-old biotech company that has not had a U.S. product approved since 1996.

Last year, prescription and over-the-counter diet drugs took in just $381.5 million, according to IMS Health.

If Qnexa wins a green light from FDA, that figure could soar. Analysts estimate Vivus' drug could take in nearly $689 million in sales by 2014, according to consensus forecast data from Thomson Reuters.

Current weight-loss drugs have not gained much traction, as most only trim a few pounds but carry serious or unpleasant side effects such as heart risks or gas.


In general, the FDA is in agreement with the company with respect to the weight-loss effects of the drug, said Eric Coleman, deputy director of the FDA division that oversees metabolic drugs. The focus is primarily on safety.

The drug's potential to cause congenital defects in unborn babies is a particular concern, especially since women of childbearing age are the pill's target customer.

So far, analysts have been confident about Vivus' ability to overcome safety hurdles.

The critical factor in looking at the data is the enormous benefit that (Qnexa) provides, said Ira Loss of Washington Analysis Corp, who follows the FDA for financial clients. The risks are not insurmountable. They can be managed.

Qnexa attempts to improve on the infamous fen-phen diet drug. It combines one of fen-phen's ingredients -- the appetite suppressant phentermine -- with the anti-seizure drug topiramate. Fen-phen's other ingredient, fenfluramine, was pulled off the market in 1997 when serious heart valve problems emerged.

Patients taking Qnexa saw between 3 percent and 9 percent weight loss over placebo, depending on how much of the drug they took, FDA staff said in a memo on Tuesday. Patients also saw improved blood pressure, and better fats and sugar levels in the blood.

Industry watchers and Vivus competitors will also be watching the advisers' meeting for clues on the FDA's thinking ahead of similar reviews last this year of two rival drugs, from Arena Pharmaceuticals and Orexigen Therapeutics, whose shares have also soared.

Diet pills already on the market include Abbott Laboratories' Meridia, which carries several heart-related risks, and Roche Holding AG's Xenical, which causes liver problems and uncontrolled bowel movements.

Imagine what a drug can do that doesn't have side effects and removes more weight, said Leerink Swann analyst Steve Yoo.

FDA approval would give Vivus its second U.S. drug since its 1997 launch of Muse, an erectile dysfunction suppository that took in just $15.8 million in net U.S. revenue in 2009. The company's efforts to market a sexual dysfunction cream for women flopped in 2006. (Reporting by Susan Heavey and Jonathan Lentz; additional reporting by Susan Kelly in Chicago; Editing by Bernard Orr and John Wallace)