Cause: Excessive serotonin, usually caused by prescription or illicit drugs including:
Antidepressants like MAOIs, tricyclics, SSRIs, trazodone, nefazodone (Serozone), buspirone (Buspar), clomipramine (Anafranil), venlafaxine (Effexor)
Pathophys:Excessive serotonin peripherally and in CNS causes sx. Onset can occur with the 2nd precipitating drugs added even weeks after stopping 1st drug, eg, w fluoxetine
Sx:After precipitating drug taken, rapid onset of anxiety, diaphoresis, shivering
Si: (*=most important si, and, if present, dx is likely)
Mild—tachycardia, diaphoresis, shivering, mydriasis (dilated pupils), tremor, myoclonus, hyperreflexia*
Moderate—above plus hypertension, hyperthermia to 40°+C, hyperactive bowel sounds, clonus*especially in lower extremities or ocular, agitation/hypervigilance, pressured speech, reptitive head turning w neck in extension
Severe—big hypertension and tachycardia leading to shock, agitated delirium, muscle rigidity*and hypertonia especially in lower extremities, fever >41°C, metabolic acidosis, rhabdomyolysis, seizures
DIC, shock, renal failure; all due to uncontrolled hypertension?
r/o: Dx's listed above under NMS and malignancy hyperthermia
Rx:Supportive iv fluids
Diazepam or other iv benzodiazepines
Cyproheptadine po or via ng tube, 12 mg × 1, then 2 mg q2h until until better up to 32 mg/day, 8 mg po q8h maintenance until causes cleared
Chlorpromazine 50-100 mg im
Olanzapine 10 mg sl?
of fever: no antipyretics; general anesthesia and intubation (avoid succinylcholine) if can't control fever and if necessary to eliminate muscle rigidity