NB32 is an investigational medication being evaluated for weight loss. It is a fixed-dose combination of bupropion sustained-release (SR) and Orexigen´s proprietary SR version of naltrexone, designed to improve drug tolerability.
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 by increasing activity of POMC neurons. Naltrexone works by blocking opioid receptors on the POMC neurons, preventing feedback inhibition of these neurons and further increasing POMC activity. In addition, NB32 may regulate activity in the dopamine reward system of the brain that helps control food cravings and overeating behaviors.
NB32 is believed to reduce appetite, help control cravings, increase metabolism and improve control over eating behaviors. In previous clinical trials involving more than 4,500 people, NB32 has been shown to help people lose weight and keep it off for up to one year. Additionally, in these studies, 53 percent of study participants taking NB32 and 21 percent of those taking placebo lost five percent or more of their body weight over the 12 month trial duration. Those who took NB32 for six months, combined with a structured weight management program, lost an average of 25 pounds, compared with 17 pounds for those using the weight management program and receiving placebo. Many patients saw noticeable improvements in cholesterol levels, and blood sugar control, as well as smaller waistlines. Those who combined NB32 with diet and exercise experienced the most reduction in body weight.
NB32 was generally well tolerated in clinical trials. In the NB32 clinical development program, the most frequent adverse events on NB32 were nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea. These were mostly mild to moderate in severity and did not last long.
NB32 is currently being evaluated in the Light Study, a multicenter, randomized, double-blind, placebo-controlled long-term research study. The Light Study is designed to assess the cardiovascular health outcomes of NB32.
COR-I (NB-301) A 56-week study assessing the safety and efficacy of NB32 in 1,742 healthy, nondiabetic, obese patients.
COR-II (NB-303) A 56-week study designed to assess the safety and efficacy of NB32 in 1,496 healthy, nondiabetic, obese patients.
COR-Diabetes (NB-304) A 56-week study designed to assess the safety and efficacy of NB32 in 505 obese patients with Type 2 diabetes.
COR-BMOD (NB-302) A 56-week study designed to evaluate the safety and efficacy of NB32 alone or when combined with intense diet, exercise and behavior modification in 793 patients.