Contrave has received approval from the Food and Drug Administration, clearing the way for the new weight loss drug to hit the market. The drug is designed for treatment of chronic weight problems, when combined with diet and exercise.

Naltrexone hydrochloride and bupropion hydrochloride are combined, and packaged in extended-release tablets to create the new drug. Each of those components have previously been approved by the FDA for different purposes, although the delivery method and purpose is new.

Contrave may soon be prescribed for obese adults, having a body-mass index (BMI) of 30 or greater, The Centers for Disease Control and Prevention estimate one in three Americans fit into this category. The drug is also approved for overweight adults, having a SMI over 27, if they have experienced high blood pressure, high cholesterol, or type 2 diabetes.

Bupropion is currently used to treat depression, as well as seasonal effective disorder (SAD). The drug is also prescribed to assist people who are trying to quit smoking tobacco. Naltrexone is used to treat dependence on alcohol and opiate drugs.

A study of the effect of the hybrid drug on weight loss examined 4,500 obese and overweight patients. Investigators placed all subjects on a diet and activity plan designed to help them lose weight.

Contrave was found to lead to a weight loss of 4.1 percent more than subjects provided with a placebo.

"In this trial, 42 percent of patients treated with Contrave lost at least five percent of their body weight compared with 17 percent of patients treated with placebo," the FDA reported in a press release.

A second study examined patients afflicted with type 2 diabetes, showing an improvement of two percent in people who took the drug, over those in the study group. In this study, 36 percent of those provided with Contrave lost five percent or more of their body weight, double the rate who were not given the drug.

The body-mass index measures amounts of body fat based on the height and weight of a patient.

Contrave works quickly, and the FDA recommends cutting off treatment if patients do not lose five percent of their body mass in 12 weeks.

Belviq and Qsymia are already available to consumers seeking a chemical aid for weight loss.

In June, the FDA delayed approval for three months, based on concern about labeling. Because Bupropion is an anti-depressant, Contrave will need to carry a warning about increased risk of suicidal thoughts.

Orexigen Therapeutics, the company that developed the drug, has not yet announced when the new medicine would be available to the public.