FDA approval given for new drug to treat obesity

FDA has approved a combination of the generic drugs naltrexone and bupropion (Contrave) for chronic weight management in obese adults (body mass index [BMI] >30 kg/m²). This combination agent has also been approved for use in those patients who are overweight (BMI >27 kg/m²) and have at least 1 weight-related comorbid condition such as diabetes, hypertension, or dyslipidemia.

This extended-release tablet formulation of naltrexone/bupropion is made by Orexigen Therapeutics and marketed by Takeda Pharmaceuticals. The drug decreases appetite and is intended to be used as an adjunct to lifestyle modifications including a reduced-calorie diet and increased physical activity.

“It's important that physicians and appropriate patients have options when discussing weight management, especially when you look at the prevalence of obesity in today's society,” says Douglas Cole, president of Takeda USA.

Of the combination, naltrexone has been used to treat alcohol and opioid addiction and the antidepressant bupropion has been used to aid smoking cessation. Used together the 2 drugs are believed to have effects on areas of the brain, the hypothalamus and the mesolimbic dopamine circuit, which are involved in the regulation of food intake.

Clinical trials have evaluated the effectiveness of naltrexone/bupropion in about 4,500 obese and overweight patients both with and without weight-related health conditions who were treated for 1 year. Lifestyle modification including a reduced-calorie diet and regular physical exercise was part of the treatment. In a trial of nondiabetic patients those who received naltrexone/bupropion lost 4.1% more weight than did those on placebo; 42% of treated patients lost at least 5% of their body weight. In another trial including patients with type 2 diabetes the weight loss for those on the drug was 2% more than that lost by those on placebo; 36% treated with the drug lost at least 5% of their body weight.

According to the Centers for Disease Control and Prevention (CDC) 78.6 million, or one-third, of adults living in the United States are obese. The 2012 estimate from the National Health and Nutrition Examination Survey (NHANES) indicated that 1 of 3 adults (35%) age 20 years and older are classified as obese as defined by a BMI >30 kg/m².

FDA is approving naltrexone/bupropion with the caveat that it comes with a boxed warning indicating that it might increase suicidal thoughts and behaviors. Among possible side effects for naltrexone/bupropion are increases in blood pressure and resting heart rate. Patients should be monitored for both. As a post-marketing requirement, FDA will receive the results from long-term cardiovascular safety studies to be conducted by the maker.

It is expected that naltrexone/bupropion will be commercially launched this autumn.