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M. J. Zylstra, B. E. Ruck2 and S. M. Marcus
Introduction: New medications for the management of obesity are rapidly coming through the drug design pipeline. Among those recently approved is Contrave®, [naltrexone/bupropion] which has shown a modest and clinically relevant weight loss. We report two cases of naltrexone-induced opioid withdrawal resulting from the prescription of Contrave® to opioid-dependent patients. Case details: Patient 1 was a 59-year-old male with chronic pain prescribed morphine 60 mg and oxycodone 30 mg daily. He was prescribed Contrave® as adjunct to lifestyle modifications in the management of his obesity. Withdrawal symptoms precipitated within a few hours of his first dose. The resultant vomiting and anxiety led to patient distress and an emergency department visit. Patient 2 was a 42-year-old female former heroin user on methadone maintenance 90 mg daily. She was started on Contrave® as an effort towards meaningful weight loss. Within the first hour after her first dose she began to have withdrawal symptoms. On arrival at the ED the patient was agitated and nauseated, and required treatment with IV fluids, lorazepam, and ondansetron for her symptoms. Discussion: As a naltrexone-containing product, there is the potential for the induction of withdrawal in opioiddependent patients. Physicians may be unaware of the inclusion of this opioid antagonist in the newly marketed medication or overlook the ability of naltrexone to produce acute withdrawal. Pharmacy profiles might not reveal that a patient is on methadone maintenance or using opioid medications illicitly. Patients may not always provide a complete medication history, and may not report opioid usage to their health care providers without direct questioning. Thus, clinicians and pharmacists must ask about the use of other medications and or illicitly used drugs and caution patients about this potential interaction.