Merck Weight Loss Drug Effective But With Some Side Effects

Merck & Co.’s experimental weight loss drug Taranbant was given to obese patients in low doses. The patients experienced significant weight loss, but side effects showed on the interim results from the pivotal trial released by the company on Monday.

A year of Taranbant 2mg doses coupled with diet and exercise made 2,500 patients lose an average of 14.5 pounds (57%), compared to the weight loss of 5.7 pounds (27%) experienced by the group given placebo. However, Merck discontinued a study of patients given more than 2mg doses as it increased side effects including depression, nausea and irritability.

Taranabant is a type of medicine from the rimonabant family, a Sanofi-Aventis SA drug that was rejected by the U.S. regulators in 2007 after being linked to depression and suicidal thoughts.

“We believe we have a different profile. We didn’t see the same neurological effects in preclinical trials that they did,” said Dr. John Amatruda, vice president of Merck’s metabolism clinical research.

Dr. Amatruda says the company plans on filing Taranabant for the U.S. regulatory approval, but declined to confirm if the application is seeking a label for weight loss.

The trial also showed the new drug improved cholesterol levels while reducing the risk of metabolic syndrome, a group of risk factors for diabetes and heart disease. However, the triall will continue for another year, expecting several pivotal trials with 0.5 mg doses and a study with diabetes patients.

Merck & Co. remains confident of its clinical development program, including a one-year extension for all existing and new trials to broaden and address safety issues from the FDA rimonabant review.

“Our compound appears to be a little more potent. The weight loss they had with 20 mg is close to what we have with 2 mg,” Amatruda said.