Mysimba (naltrexone/bupropion) and Opioids: Risk of Serious Side Effects Identified

The European Medicines Agency (EMA) is alerting healthcare professionals and patients about significant risks identified with the combined use of Mysimba (naltrexone/bupropion) and opioid-containing drugs. The Committee for Risk Assessment in Pharmacovigilance (PRAC) has noted the potential for rare but severe reactions, including seizures and serotonin syndrome, when Mysimba is taken concurrently with opioids. Mysimba is a medication prescribed for weight management in adults, alongside diet and exercise. While not widely available in Germany, it can be obtained via single import. The simultaneous administration with opioids, such as pain relievers (morphine, codeine) and certain cough or diarrhea treatments, may result in reduced effectiveness of the opioids because naltrexone blocks their action. The EMA has highlighted these risks as disagreements persist between the drug's distributor and the agency regarding appropriate risk mitigation measures. It is crucial that Mysimba is not used by individuals undergoing opioid replacement therapy, such as methadone, or those dependent on opioids. Patients using Mysimba who require opioid treatment, for instance, for planned surgery, should discontinue Mysimba at least three days before initiating opioid therapy. The German Association of Pharmacists (ABDA) is requesting pharmacists to report any suspected adverse drug reactions related to Mysimba.