In 2014, the Food and Drug Administration approved naltrexone HCl/bupropion HCl, a combination of an antidepressant and an opioid antagonist for chronic weight management therapy. Concurrent use of antidepressants and opioids has the potential to cause drug interactions involving serotonin syndrome. Our primary objective is to identify cases of serotonin syndrome and/or opioid withdrawal after initiation of naltrexone HCl/bupropion HCl. Our secondary objective is to assess which specific opioids are more likely to cause a drug interaction with naltrexone HCl/bupropion HCl. We performed an observational study by reviewing cases in the RADARS® database from January 2014 through December 2018. The cases considered must have taken their first dose of naltrexone HCl/bupropion HCl with concomitant use of an opioid, and met the inclusion criteria. Cases were determined to involve serotonin syndrome and/or opioid withdrawal using Hunter’s Serotonin Toxicity Criteria and the Clinical Opioid Withdrawal Scale. The primary outcome measures were total number of cases with at least a moderate outcome, total number of cases determined to experience serotonin syndrome and/or opioid withdrawal and total number of cases to experience serotonin syndrome and/or withdrawal with at least a moderate outcome. The secondary outcome measures included the frequency of different opioids involved, benzodiazepine administration, and supportive care with either mechanical ventilation or intubation. Thirty-three cases in RADARS® met inclusion criteria, and 23 cases contained results for medical outcome. The 23 cases followed to medical outcome resulted in two major effects, 14 moderate effects and seven minor effects. Sixteen out of 23 cases (70%) had at least a moderate outcome. Seventeen out of 23 cases (74.0%) experienced serotonin syndrome and/or withdrawal. Overall, 13 out of 17 cases (76.5%) experienced serotonin syndrome and/or withdrawal and resulted in at least a moderate outcome. This study suggests occurrence of a drug interaction in the form of serotonin syndrome and/or opioid withdrawal with at least a moderate outcome after the first dose of naltrexone HCl/bupropion HCl while on opioid therapy.
First Committee Member (Chair)
Second Committee Member
Level of Degree
Third Committee Member
College of Pharmacy
Serotonin Syndrome, opioid, bupropion, naltrexone, antidepressant, weight loss
Logothetis, Stefanie J.. "Serotonin Syndrome and/or Opioid Withdrawal after the First Dose of Naltrexone HCl/Bupropion HCl: an Observational Study." (2019). https://digitalrepository.unm.edu/phrm_etds/24