Diet pills: Vivus, Arena and Orexigen in race to market safe weight-loss drugs

On NBC's hit series The Biggest Loser, obese contestants must huff and puff through weeks of endless push-ups, sit-ups and treadmill sprints in hopes of shedding more pounds than their rivals. But with all the sweat and tears required to go from fat to fabulous, many other plus-sized people are holding out for a safe diet pill that could get the same jaw-dropping results without all the effort.

Now, there may finally be some real options on the horizon. Arena Pharmaceuticals (ARNA) said Tuesday a late-stage trial of lorcaserin shows its experimental obesity drug improves patients' body composition such as body mass index and waist circumference. Meanwhile, rivals Vivus (VVUS) and Orexigen Therapeutics (OREX) are developing similar drugs. All three are racing to be the first to provide a safe drug that really works in a market potentially worth billions of dollars.

As far as lorcaserin is concerned, the study results indicated the drug improved cardiovascular risk factors such as cholesterol and triglycerides, as well as quality of life factors such as physical function, self esteem and sexual enjoyment. The company now believes the data leaves Arena on track to file for regulatory approval late this year. And according to Reuters, Arena CEO Jack Lief said the company is in discussions with potential partners.

This study adds to earlier findings that 47.2 percent of subjects taking lorcaserin twice a day achieved at least a 5 percent reduction in weight -- a key threshold -- after a year. Only 25 percent of patients who took a placebo achieved the same weight loss. The study involved 4,008 patients.

More specifically, of those who completed the treatment, 63.2 percent lost at least 5 percent of their weight, compared to 34.9 percent of patients on a placebo. And 35.1 percent of these lorcaserin patients lost at least 10 percent of their weight, compared to 16.1 percent for placebo.

Obesity is one of the nation's most serious public health problems. According to the National Institutes of Health, 65 percent of U.S. adults are overweight or obese. The economic costs associated with obesity are significant, too, with the nation's annual medical burden from the condition estimated at $147 billion in 2008, according to a recent report in Health Affairs.

Unquestionably, the market for diet drugs could be very large, which is why analysts believe there may be room for all three companies: Arena, Vivus and Orexigen. Since a 5 percent to 10 percent decrease in weight can be medically significant, there's bound to be demand for the drugs. What's more, each drug is designed to appeal to a specific group of patients.

The drugs belonging to Arena's rivals achieved better weight-loss results. For example, Vivus' Qnexa reduced patients' weight by up to 14.7 percent (with the full dose), on average.

Arena is differentiating itself by trying to position lorcaserin as the safest of the drugs. While the other two drugs use phentermine which is know to increase blood pressure, Arena's drugs sometimes even decreased it, as Lief told Xconomy's

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