Olanzapine Overdose Mimicking Opioid Intoxication,☆☆,,★★

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Abstract

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 α 2 -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.]

Section snippets

INTRODUCTION

We present the cases of 4 patients with toxic effects related to olanzapine ingestion. All patients exhibited marked miosis and depressed mental status, findings usually associated with opioid or α 2 -adrenergic agonist intoxication but which have not been previously described with neuroleptic agents. We suggest that olanzapine intoxication be added to the list of ingestions that can cause miosis.

Olanzapine (Zyprexa) is a thienobenzodiazepine neuroleptic agent. It has similar receptor affinity,

CASE REPORTS

Four patients presented to 2 hospitals in the Denver area over a period of 9 months with alterations in mental status believed to be caused by drug ingestion. Involvement by our toxicology service in case 1 was by telephone consultation, and in the other cases it was by direct bedside management. Our approach in each case involved stabilization, decontamination, exclusion of life-threatening toxic effects, and supportive care. In all cases, serum was collected at the time of presentation and

DISCUSSION

All 4 patients had profound mental status depression and miosis after deliberate ingestion of olanzapine. This is not consistent with previous published reports. We believe that this finding is a direct consequence of olanzapine toxicity.

Phase 2 clinical trials of olanzapine revealed comparable or superior efficacy, compared with haloperidol, in the treatment of various aspects of schizophrenia, with a lower incidence of adverse events.3 Adverse events reported in clinical trials were

References (10)

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From Rocky Mountain Poison and Drug Center, Denver, CO.

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Address for reprints: Gerald F O’Malley, DO, Rocky Mountain Poison and Drug Center, 8802 East Ninth Avenue, Denver, CO 80220-6800; 303-739-1100, fax 303-739-1119;E-mail [email protected].

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