Two Cases of Serotonin Syndrome After Bupropion Overdose Treated With Cyproheptadine

Bupropion is not known to have direct serotonin agonism or inhibit serotonin reuptake. In spite of this, it has been implicated as a causative agent of serotonin syndrome. We highlight two cases of single-agent bupropion overdose that subsequently met the diagnosis of serotonin syndrome by the Hunter criteria, despite the absence of direct serotonergic agents. CASE 1: A 14-year-old boy intentionally ingested an estimated 30 bupropion 75-mg immediate-release tablets. He presented in status epilepticus, was intubated, and was placed on midazolam and fentanyl infusions. He developed tremor, ankle clonus, and agitation. He was administered cyproheptadine for presumed serotonin syndrome with temporal improvement in his symptoms. CASE 2: A 19-year-old woman intentionally ingested an estimated 53 bupropion 150-mg extended-release tablets. She had a seizure and required sedation and intubation. During her course, she developed hyperthermia, inducible clonus, and hyperreflexia. She was treated with cyproheptadine without temporal improvement of symptoms but improved the following day. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although bupropion is not known to be directly serotonergic, it has been implicated as the single causative agent after overdose. This may be due to an indirect increase in activity of serotonergic cells. In these cases, bupropion overdose resulted in a clinical presentation consistent with serotonin syndrome, with the first having a temporal improvement after treatment with cyproheptadine. Physicians need to be aware of the potential serotonergic activity of bupropion for accurate assessment and treatment of this dangerous condition.