Orexigen Therapeutics announced that it has successfully completed its previously announced acquisition of the United States rights to Contrave (naltrexone HCl/bupropion HCl extended release) and relaunched Contrave with the company's own sales organization. The acquisition was originally announced March 2016 and was completed two months ahead of schedule.

"We are pleased to announce the accelerated completion of the acquisition of all US rights to Contrave. This transformational event creates a 'New Orexigen', magnifying our anticipated long-term corporate profitability and enabling new strategic options for the company," said Michael Narachi, Orexigen's CEO. "We are in full execution mode with our team of dedicated and seasoned individuals focused on growing the US Contrave business in order to help improve the health and lives of obese patients struggling to lose weight."

Orexigen is now entitled to 100 per cent of net sales and controls all US commercial and development activities. Outside the US, Orexigen's strategy is to commercialize Contrave and Mysimba, as the drug is known in Europe, through partnerships.

This year US pharmacies will fill approximately 11 million prescriptions for anti-obesity medications, including branded drugs as well as generic amphetamines, which have approximately 75 percent share of the overall market. Contrave was launched in October 2014 and by June 2015 had become the leading branded anti-obesity drug.

"Over the next three years, we have the potential to achieve our sales and profitability targets through execution on three key strategies: launching an effective and efficient US commercial organization focused on the highly concentrated 20,000 health care practitioners who write the majority of prescriptions for Contrave and other branded and generic anti-obesity medicines; achieving strong growth of Contrave by differentiating versus generic amphetamines; and improving the gross to net ratio through appropriate discount and pricing strategies," said Dr. Thomas Cannell, chief operating officer and president of Global Commercial Products.

Contrave, approved by the United States Food and Drug Administration in September 2014, is indicated for use as an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in adults with an initial body mass index (BMI) of 30 kg/m2 or greater (obese), or 27 kg/m2 or greater (overweight) in the presence of at least one weight-related comorbid condition (e.g., hypertension, type 2 diabetes mellitus or dyslipidemia).

The exact neurochemical effects of Contrave leading to weight loss are not fully understood. Contrave has two components: naltrexone, an opioid antagonist, and bupropion, a relatively weak inhibitor of the neuronal reuptake of dopamine and norepinephrine. Nonclinical studies suggest that naltrexone and bupropion have effects on two separate areas of the brain involved in the regulation of food intake: the hypothalamus (appetite regulatory center) and the mesolimbic dopamine circuit (reward system).

Four 56-week multicenter, double-blind, placebo-controlled phase 3 clinical trials were conducted to evaluate the effect of Contrave in conjunction with lifestyle modification in 4,536 subjects randomized to Contrave or placebo. In these studies, the most common adverse reactions (>5 per cent) seen in patients taking Contrave included nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea.