Contrave®
Background
Contrave is a fixed dose combination of naltrexone sustained release (SR) and bupropion SR. We chose these constituents based on the results of our screening model as well as our understanding of the circuitries in the brain that regulate appetite and energy balance. In particular, naltrexone was chosen as a complement to bupropion in order to block compensating mechanisms that attempt to prevent long-term, sustained weight loss.
Naltrexone was approved in the United States in 1984 for the treatment of opioid addiction and in 1995 for the treatment of alcoholism. Naltrexone works by blocking opioid receptors in the brain and inhibits the reinforcing aspects of addictive substances, reducing their perceived reward. It has been shown in numerous studies to negatively alter the palatability of many foods, particularly sweets.
Bupropion was approved for marketing in the United States in 1985 for depression and in 1997 for smoking cessation. Functionally, bupropion is thought to increase the level of dopamine activity at specific receptors in the brain, which appears to lead to a reduction in appetite and increase in energy expenditure. It is currently among the most commonly prescribed anti-depressants in the United States. Bupropion has become popular in the treatment of depression not only for its clinical efficacy, but also its attractive side effect profile, including modest weight loss.