SERTRALINE-PHENELZINE DRUG-INTERACTION - A SEROTONIN SYNDROME REACTION

OBJECTIVE: To report a serious drug interaction possibly occurring wit h the monoamine oxidase inhibitor phenelzine and the selective seroton in reuptake inhibitor sertraline. CASE SUMMARY: A 61-year-old woman wi th treatment-refractory major depressive disorder was being treated un successfully with lithium, phenelzine, thioridazine, and doxepin. Sert raline 100 mg/d was added to the patient's therapy. Within three hours of ingesting the first dose, the patient experienced a dramatic incre ase in her temperature, pulse, and respirations along with labile bloo d pressure, and symptoms of rigidity, diaphoresis, shivering, and decr eased sensorium. The patient was transported to the emergency room and treated with diazepam 10 mg iv, followed by midazolam 10 mg iv for co ntrol of rigidity. She was also intubated. The patient then experience d precipitous falls in her blood pressure and respiratory rate. Ice pa cks combined with a cooling blanket and dantrolene 80 mg iv were admin istered to control fever and rigidity, respectively. She had an initia l working diagnosis of neuroleptic malignant syndrome, which was later changed to serotonin syndrome. Dantrolene was continued for 72 hours at which time the patient was extubated,and transferred to a psychiatr ic unit. CONCLUSIONS: Selective serotonin reuptake inhibitor antidepre ssants should not be combined with monoamine oxidase inhibitor antidep ressants because of the risk of serotonin syndrome.