Proposed Merck Weight-Loss Drug Linked To Psychiatric Events
CHICAGO -(Dow Jones)- A proposed Merck & Co. (MRK) drug helped people lose more weight than those not taking the drug, but was linked to higher rates of certain psychiatric events.
The proposed drug, taranabant, is similar to Sanofi Aventis SA’s (SNY) rimonabant, which was rejected by a Food and Drug Administration panel last year over concerns about suicidal thoughts and behaviors. Sanofi later pulled the application from the FDA and sells the product under the brand name Acomplia in Europe and some South American countries.
Merck released the first set of Phase III data involving taranabant at the American College of Cardiology’s annual meeting here. The study followed patients for a year and involved a two-, four- or six-milligram dose of the drug as well as placebo group or patients who received a fake drug.
The Whitehouse Station, N.J., firm already announced that it didn’t plan to move forward with the four- and six-milligram doses of the drugs largely because of similar psychiatric side effects that so far have hampered approval of rimonabant in the U.S.
A data-safety monitoring board overseeing Merck’s two-year study recommended stopping the six-milligram dose of the study because it had a higher rate of psychiatric side effects and wasn’t much better at cutting weight than patients on a four-milligram dose.
Merck decided to scrap both the six- and four-milligram doses but is moving forward developing doses at two milligrams and lower.
Both taranabant and rimonabant are designed to help block a chemical in the endocannabinoid system, a physiological system in the body believed to play a role in how the body regulates food intake. However, the FDA has expressed concerns that blocking the same chemical could increase the risk for other problems, including mood disorders and neurodegenerative disorders such as multiple sclerosis.
The study involved about 2,500 patients considered obese or overweight who had risk factors for developing cardiovascular disease or diabetes such as high blood pressure or higher than normal blood-sugar levels.
About 400 patients each were in the placebo group and in the two- and four- milligram groups. About 1,200 patients were in the six-milligram group. Patients in all treatment groups also were placed on a diet and exercise regimen in addition to therapy or placebo.
Patients on the two-milligram dose of taranabant lost an average of 14.5 pounds after taking the drug for a year compared to an average 5.7-pound loss for patients in the placebo group. The study also showed that more than two times as many patients treated on the two-milligram dose, or 231 patients, lost 5% of their baseline body weight compared with 113 patients on placebo, and that three times as many patients had more than 10% weight loss after a year compared to the placebo group. Doctors consider a 5% or 10% total weight loss to be medically significant.
Overall, the study showed that 28.4% of patients in the two-milligram taranabant group reported some type of psychiatric event, compared with 20.3% in the placebo group. However, there were no reports of suicides, suicide attempts or thoughts about suicide in either the placebo, two- or four-milligram taranabant groups. Slightly more patients in the two-milligram group reported depression than those on the placebo group, while there was a statistically significant difference in reports of irritability among patients taking two- milligrams of taranabant compared to placebo.
John Amatruda, a vice president of clinical research at Merck Research Laboratories, said he was confident the company would continue collecting additional clinical data and would be able to present a “rich” dataset to the FDA when it seeks approval for taranabant.