Healthcare professionals and patients should be aware of new guidance from the European Medicines Agency (EMA) regarding the use of Mysimba (naltrexone/bupropion) by Orexigen Therapeutics in combination with opioid-containing medications. Following a routine safety review, the EMA’s Committee for Medicinal Products for Human Use (CHMP) advised strengthening existing precautions to minimize the risks associated with these drug interactions.
Healthcare practitioners need to recognize that opioid painkillers may not work effectively in patients taking Mysimba. This is due to naltrexone, one of the active substances in Mysimba, which blocks the effects of opioids. Patients are advised to discontinue Mysimba at least three days before starting any opioid treatment, such as morphine, codeine, other opioids used during surgery, or certain medications for cough, cold, or diarrhea. The combination of these drugs poses a rare but serious and potentially life-threatening risk, including seizures and serotonin syndrome.
Healthcare Guidance: EMA Adds New Contraindications for Mysimba Use with Opioid Medications
The new recommendation adds to existing contraindications, which state that Mysimba must not be used by individuals dependent on long-term opioids, those receiving treatment with opioid agonists like methadone, and those undergoing opioid withdrawal. The EMA also highlighted the necessity of testing to ensure the clearance of opioid medication before starting treatment with Mysimba.
Mysimba was granted marketing authorization in March 2015 and is used to manage weight in adults with obesity (BMI 30 or more) or overweight (BMI 27-30) who have weight-related complications such as diabetes or hypertension. The combined actions of its two component drugs, naltrexone and bupropion, reduce appetite and increase energy expenditure, helping patients maintain a calorie-controlled diet and reduce body weight.
The efficacy of Mysimba in reducing body weight was demonstrated in four main studies where it was compared with a placebo. In three studies, the average weight loss in patients treated with Mysimba ranged from 3.7% to 5.7%, compared to 1.3% to 1.9% in those treated with placebo. In a fourth study, where patient counseling was more intensive, the overall weight loss was 8.1% with Mysimba and 4.9% with placebo.
Healthcare Alert: Regular Monitoring of Mysimba Essential; Discontinue if Ineffective or if Side Effects Occur
Patients’ response and tolerability to Mysimba should be regularly monitored. Treatment should be discontinued in patients who experience certain side effects, such as an increase in blood pressure, or in those who have not lost at least 5% of their initial body weight after four months of treatment.
The EMA’s update underscores the importance of healthcare professionals closely monitoring the medications their patients are taking and ensuring they follow the latest guidelines to prevent harmful drug interactions. This is particularly crucial for those patients on Mysimba who may need opioid-containing medications for pain management or other conditions. The goal is to maximize the therapeutic benefits of Mysimba while minimizing potential risks, ensuring safe and effective treatment for all patients.
In conclusion, the EMA’s strengthened guidance on the use of Mysimba and opioid-containing medications serves as a critical reminder of the importance of vigilance in medication management. Both healthcare providers and patients must be informed and proactive in following these updated recommendations to ensure safety and efficacy in weight management and pain treatment regimens.
Resource: Europen Medicines Agency, July 26, 2024
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