Orexigen Therapeutics, Inc., a biopharmaceutical company focused on the treatment of obesity, announced that its wholly-owned subsidiary Orexigen Therapeutics Ireland Ltd. and Kwang Dong Pharmaceutical Company, Ltd. inked distributorship agreement for South Korea for Contrave (naltrexone HCl / bupropion HCl extended release) monotherapy for weight management in overweight or obese adult patients.

Under the terms of the agreement, Kwang Dong will be responsible for seeking regulatory approval and for all commercialisation activity and expenses. Orexigen will supply Contrave tablets to Kwang Dong for a $7 million upfront payment, approximately 35 – 40 per cent of net sales, potential sales-based milestone payments, and other fees. Kwang Dong expects to begin marketing Contrave in the second half of 2016, if regulatory approval is obtained.

"Kwang Dong's established relationships with obesity societies and opinion leaders as well as their strong consumer marketing capabilities make them an ideal partner for Contrave in Korea," said Mike Narachi, chief executive officer of Orexigen.

"We look forward to working closely with them to obtain regulatory approval and have a successful commercial launch."

Obesity and related comorbidities are a serious health problem in South Korea, where approximately 38 per cent of men and 26 per cent of women are obese according to recent statistics from the National Health Institute. In 2014, sales of anti-obesity prescription medicines exceeded $67 million in Korea.

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). In Europe, the medicine was approved in March 2015 with the brand name Mysimba.

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.

The clinical trial programme also includes a double-blind, placebo-controlled cardiovascular outcomes trial known as the Light Study. The primary objective of this study was to evaluate the occurrence of major adverse cardiovascular events (MACE) in overweight and obese adults with cardiovascular risk factors receiving Contrave. A second study, designed to address post-approval requirements in both Europe and the United States, is planned in order to further evaluate cardiovascular outcomes.