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New Weight Loss Combination Ready for FDA Approval

Aug 14, 2010

by Isaak Smith, PharmD Candidate, University of Florida College of Pharmacy

Contrave (naltrexone SR/bupropion SR) is an investigational product from Orexigen, a company that specializes in the treatment of obesity. Contrave has just completed phase-3 trials (COR-1, COR-2, COR-BMOD, and COR-diabetes) and Orexigen has submitted an NDA to the FDA for approval.


The theory behind Contrave is that the bupropion may actually cause the weight loss to occur while the naltrexone may help inhibit the body’s trend towards stopping weight loss from occurring. Weight loss is a known possible side effect of bupropion use. So while lifestyle changes are likely the best way to achieve weight loss, Contrave seeks to improve adherence to those changes.

The results of all four arms of the COR trials showed similar results. Of particular interest is comparing the COR-1 vs. the COR-BMOD trial. The primary difference between the two was the addition of intensive behavioral modification (BMOD) in the BMOD arm. The COR-1 showed statistically significant results of weight loss when compared to placebo despite not having the BMOD. The results were more significant when BMOD was added, but both showed promising results. Also, the COR-diabetes arm showed a decrease in A1c of 0.6% as opposed to 0.1% with placebo with similar weight loss. The results of the COR trials were consistent with previous studies done with these two medications.

Adverse effects were limited in the trials to known side effects of both of the medications. The main side effects noticed were nausea, constipation, and headache. Serious adverse effects were limited, but known side effects such as seizures with bupropion did occur in rare instances. However, other positive effects were noticed such as decrease in blood pressure and A1c. The changes in blood pressure were better in the placebo group, but bupropion can cause a small increase in blood pressure. The overall net effect was positive in all arms. These seemed consistent with expected improvements upon weight loss.

  1. http://www.pipelinereview.com/index.php/2010080336072/Small-Molecules/Orexigen-Therapeutics-COR-BMOD-Study-Published-in-the-Journal-Obesity.html accessed August 12, 2010
  2. http://www.news-medical.net/news/20100628/Orexigen-Therapeutics-announces-data-from-CORDiabetes-trial-for-Contrave.aspx accessed August 12, 2010
  3. http://www.orexigen.com/candidates/candidates_contrave.php accessed August 12, 2010
  4. Clinical Pharmacology accessed August 12, 2010
  5. Greenway et al. Effect of naltrexone plus bupropion on weight loss in overweight and obese adults (COR-1): a multicenter, randomized, double-blind, placebo-controlled, phase-3 trial. The Lancet, July 30, 2010 DOI:10.1016/S0140-6736(10)60888-4.
  6. Greenway F et al. Comparison of combined bupropion and naltrexone therapy for obesity with monotherapy and placebo. J Clin Endocrinol Metab. 2009 Dec;94(12):4898-906. Epub 2009 Oct 21.

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