Fatal serotonin toxicity caused by moclobemide and fluoxetine overdose

Both moclobemide and fluoxetine are used in the treatment of depression, and have been shown to produce fewer side effects than conventional tricyclic antidepressants. A combination of moclobemide and fluoxetine has been used in refractory depression, however there is potential for severe serotonin toxicity. We describe a lethal case of serotonin toxicity in a 36 year-old woman after she ingested multiple drugs, including moclobemide 4500 mg, fluoxetine 200 mg, propranolol 300 mg and several benzodiazepines. The clinical features included coma, mydriasis, hyperthermia, tremor, hyperreflexia, rhabdomyolysis, renal failure and respiratory insufficiency. Eventually, the patient died of disseminated intravascular coagulation and circulatory collapse at 22.5 h postingestion. Toxicological analysis of the patient's blood confirmed high levels of moclobemide 150 μg/mL (therapeutic 1-3 μg/mL), fluoxetine 3750 ng/mL (therapeutic 47-469 ng/mL) and several benzodiazepines. In conclusion, a combination of moclobemide and fluoxetine should be avoided in depressed patients with high suicidal tendencies. Moreover, early recognition and aggressive intervention are the mainstays in the management of potentially life-threatening serotonin toxicity.