Olanzapine Overdose Mimicking Opioid Intoxication

We report significant central nervous system depression and the previously unreported phenomenon of pupillary constriction after acute overdose of olanzapine (Zyprexa) in 4 patients. Phase 2 trials describe a typically benign course in overdose, and published abstracts note a wide spectrum of clinical effects with supratherapeutic ingestion of olanzapine. Our patients demonstrated profound central nervous system depression, and 2 required advanced airway support. All 4 patients recovered with supportive care. Olanzapine should be added to opioid and α2 -adrenergic agonist intoxication in the differential diagnosis of the patient with depressed mental status and miosis. [O’Malley GF, Seifert S, Heard K, Daly F, Dart RC: Olanzapine overdose mimicking opioid intoxication. Ann Emerg Med August 1999;34:279-281.]