Merck's Weight Loss Trial Reports Success, Side Effects

Armen Hareyan's picture

Merck has reported both positive and negative results from its pivotal trial showing that patients taking Taranabant significantly loose weight, but they also suffer from adverse side effects.

Merck conducted a pivotal trial including 2500 patients. The trial lasted a year and included regular exercising and diet. Patients taking 2mg dose lost 14.5 pounds (6.6 kg) in average, compared to 5.7 pounds of those taking a placebo. Taranabant taking patients weighed 4% less than those taking a placebo just 36 weeks after trial start.


57% of trial participants lost at least 5% of initial weight, compared to 27% of those taking a placebo. Taranabant also showed improved levels of cholesterol, reduced metabolic syndrome frequency, cut factors leading to heart disease and diabetes.

However, Taranabant showed to have adverse side effects as well, especially when taking high doses. Among side effects study declares gastrointestinal distress in 42% patients taking 2mg dose, compared to 29% in placebo group. 28% of patients also reported psychiatric disorders and irritability, compared to 20% placebo taking patients. Those taking higher 6mg dose of Taranabant reported thoughts of suicide.

During the trial 13% of patients dropped out, because of the side effects, compared to 8% of those taking placebo.

This trial considered 2mg Taranabant dose and reported significant success in weight loss, but it also reported adverse side effects. Therefore, Merck is planning to conduct another trial considering 0.5mg Taranabant dose. New trial will also consider the effect of the drug on diabetes patients. Later, the drug will be submitted for FDA's approval.