SEROTONIN SYNDROME FROM VENLAFAXINE-TRANYLCYPROMINE INTERACTION

Excessive stimulation of serotonin 5HT(1A) receptors causes a syndrome of serotonin excess that consists of shivering, muscle rigidity, sali vation, confusion, agitation and hyperthermia. The most common cause o f this syndrome is an interaction between a monoamine oxidase inhibito r (MAOI) and a specific serotonin reuptake inhibitor. Venlafaxine is a new antidepressant agent that inhibits the reuptake of serotonin and We report a venlafaxine-MAOI interaction that resulted in the serotoni n syndrome in a 23-y-old male who was taking tranylcypromine for depre ssion. He had been well until the morning of presentation when he took 1/2 tab of venlafaxine. Within 2 h he became confused with jerking mo vements of his extremities, tremors and rigidity. He was brought direc tly to a hospital where he was found to be agitated and confused with shivering, myoclonic jerks, rigidity, salivation and diaphoresis. His pupils were 7 mm and sluggishly reactive to light. Vital signs were: b lood pressure 120/67 mm Hg, heart rate 127/min, respiratory rate 28/mi n, and temperature 97 F. After 180 mg of diazepam iv he remained tremu lous with muscle rigidity and clenched jaws. He was intubated for airw ay protection and because of hypoventilation, and was paralyzed to con trol muscle rigidity. His subsequent course was remarkable for non-imm une thrombocytopenia which resolved. The patient's maximal temperature was 101.2 F and his CPK remained <500 units/L with no other evidence of rhabdomyolysis. His mental status normalized and he was transferred to a psychiatry ward. This patient survived without sequelae due to t he aggressive sedation and neuromuscular paralysis.