Case Presentation: A 54-year-old morbid obese female presented to the hospital with sudden-onset heart palpitations and skin paresthesia a few hours after taking a new medication she was prescribed for weight loss, bupropion/naltrexone 180/16mg once daily. The patient had a history of anxiety, for which she was prescribed citalopram 40 mg once daily. Upon her arrival to the emergency department, the patient appeared anxious, but otherwise hemodynamically stable, with a mildly elevated blood pressure. Within one hour, the patient experienced increased restlessness, agitation, inability to follow commands, hyperreflexia, and myoclonus. The patient was urgently intubated, and started on continuous infusions of propofol and midazolam for sedation. Initial blood work was unremarkable, with negative urine toxicology testing. A computed tomography scan of the head was negative for any intracranial pathology. A presumptive diagnosis of serotonin syndrome was made, and the patient was started on cyproheptadine. Further work up, which included testing for viral encephalitis, magnetic resonance imaging of the brain, and electroencephalogram was performed with negative results. After completion of cyproheptadine and noted clinical improvement, she was weaned off of sedation, eventually extubated, and transferred out of the intensive care unit with an uneventful hospital course.
Discussion: Bupropion/naltrexone is a common medication used in recent practice for weight loss. Bupropion, with its dopaminergic and noradrenergic effects, has been suggested in case reports to precipitate serotonin syndrome, both when used by itself and when in combination with other selective serotonin reuptake Inhibitors (SSRIs)[1,2,3] . Although several reports[4] showed that SSRIs combined with bupropion may increase the risk for serotonin toxicity, our case is unique in that it is among the first to suggest the concurrent use of citalopram and bupropion as a cause for serotonin syndrome. The mechanism remains unclear, but it may be related to the inhibition of serotonin metabolism. Bupropion, a CYP2D6 inhibitor[5], is partially responsible for the metabolism of citalopram. Physicians may consider decreasing the dose of citalopram while initiating weight loss medications that contain buproprion.
Conclusions: Serotonin syndrome should be considered in patients who are recently started on weight loss medications while being on antidepressants, presenting with rapidly progressive neurological symptoms. Early recognition of the condition is usually associated with good prognosis[6].