Obesity-drug maker Vivus ( VVUS - Get Report) reported results from a phase III study Thursday in which patients treated with a high dose of its experimental drug Qnexa lost 7.5% of their body weight adjusted for placebo.

The six-month, phase III "Equate" study treated more than 750 patients and compared two doses of Qnexa against the drug's individual components and a placebo.

Patients taking the high and low dose of Qnexa for six months reported an average 9.2% and 8.5% weight loss, respectively, compared to a 1.7% weight loss for patients on a placebo. Vivus said both Qnexa doses met the study's primary endpoint and were statistically significant.

Sixty-six percent of high-dose Qnexa and 62% of low-dose Qnexa patients, respectively, lost at least 5% of their body weight, compared to 15% for placebo.

Vivus did not disclose Thursday the weight loss reported by patients taking the two individual drugs that make up Qnexa, although the company did state that Qnexa's weight loss was "superior."

The Equate study is one of three late-stage clinical trials that Vivus expects to complete in the next year.

Vivus is one of three drug companies -- Arena Pharmaceutials ( ARNA - Get Report) and Orexigen Therapeutics ( OREX) are the other two -- in a race to develop the next generation of weight-loss drugs. All three companies will be releasing pivotal phase III study data in the next year.

For all the focus on weight loss, the biggest hurdle facing obesity-drug makers like Vivus is safety. In particular, the FDA is keenly focused on detecting any adverse changes in behavior or mood that may be an early signal for an increased risk in suicidal thoughts and behavior (the safety issue that scuttled Sanofi-Aventis' ( SNY - Get Report) obesity drug rimonabant).

In the Equate study, Vivus said the most common adverse events reported for Qnexa were paresthesia (tingling in the hands and feet) and dry mouth. Reported drug-related adverse events for depression and altered mood were 1.9% for the high-dose Qnexa group, 0.9% for low-dose Qnexa and and 1.8% for placebo patients.

Vivus' Qnexa consists of two currently approved drugs, combined in a proprietary formulation to promote significant weight loss without dangerous side effects. One of the drugs is phentermine, a generic weight-loss drug still available. The other drug in Qnexa is Johnson & Johnson's ( JNJ - Get Report) topiramate, used to treat epilepsy and migraines.

Vivus is holding an analyst/investor day Friday to discuss the Qnexa data. The stock was up 25 cents, or 3.8%, to $6.88 in early trading Thursday.

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