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Naltrexon/bupropion for obesity

The slimming product Mysimba®, a combination of naltrexon and bupropion, was recently included in the Dutch drug reimbursement system (Geneesmiddelenvergoedingssysteem, GVS). The drug is fully reimbursed under the national basic health insurance package, though with specific preconditions, including its use together with the Dutch programme known as combined lifestyle intervention (CLI). Its inclusion in the GVS was reported in the Dutch TV news on Tuesday 24 May 2022. Despite what this media attention suggests, results achieved with naltrexon/bupropion in terms of weight loss have been disappointing, and it is to be expected that over a third of users will discontinue the treatment for this reason. A study using cardiovascular endpoints yielded no conclusions, as it was prematurely ended. There is therefore no reason to recommend this drug to obese patients in practice.

  • The proportion of people who reduce their weight by more than 5 or 10% by treatment with naltrexon/bupropion is higher than with combined lifestyle intervention alone. The average weight loss compared to placebo is less than 5%.
  • The results are biased, for one thing by the fact that participants with insufficient weight loss or who were unable to tolerate the treatment, were removed from the study after 16 weeks.
  • The use of naltrexon/bupropion was associated with significantly more gastrointestinal, psychiatric and central adverse effects than placebo.
  • No health gains could be proven on cardiovascular end points.
  • Large-scale use of naltrexon/bupropion for the treatment of obesity should be discouraged.

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  • Marielle A.E. Nieuwhof, pharmacist