An experimental obesity drug Contrave by Orexigen Therapeutics Inc. (OREX. O) did not meet the mark set by the Food and Drug Administration leading to the company’s stock plummeting by 33.1 %.

Orexigen had said that during trials patients who were given the drug Contrave reduced body weight, improved cholesterol and other heart measures but the difference between the drug and a placebo was below the 5% benchmark set by the FDA. Canaccord analyst Adam Cutler said, "They didn't show that."

In the current study patients on the drug Contrave for a little more than a year lost between 20 and 25 pounds or between 9.3% to 11.5 % of their body weight while the patients on a placebo lost between 11 and 16 pounds, or between 5.1% to 7.3 % of their body weight. Also 41.5 % of the Contrave patients lost more than 10 % of their body weight which was double the placebo patients.

The drug also met the secondary goals of improving HDL, or "good" cholesterol, and improved potential heart risks. In the study full doses of the drug were used which is a combination of 32 milligrams of naltrexone SR and 360 mg of bupropion SR and the doses were gradually adjusted for four weeks, then given in full for 52 weeks.

No associated risks of depression or worsening of blood pressure were seen with the drug with the most common side effects being nausea, headache, constipation and dizziness, with 4.6 percent of participants dropping out of the study because of nausea. "The safety profile looks quite good. That's almost as important, if not more important, than efficacy," Cutler said.

Chief Medical Officer Eduardo Dunayevich in a statement said, "The results of this trial indicate that additional, clinically significant weight loss can be achieved when Contrave is added to a rigorous program of diet and exercise."

There are three ongoing late-stage trials of Contrave that do not include diet and exercise with the drug as this increases the amount of weight lost by all the patients, including those taking the placebo.

There are other contenders in the battle to get FDA approval and launch with their weight loss drugs in 2009 and the first is Vivus with its drug Qnexa and the other is a drug by San Diego-based Arena Pharmaceuticals Inc.

Orexigen Chief Financial Officer Graham Cooper said the company would file for U. S. regulatory approval of the drug toward the end of this year. "Side effects and tolerability are going to be critical for the FDA (U. S. Food and Drug Administration). We had a very clean profile," Cooper said.