A clozapine overdose with markedly elevated serum levels.

Clozapine (Clozaril) is an atypical antipsychotic agent used to treat schizophrenia refractory to other pharmacological agents. This report describes an accidental clozapine overdose. The half-life of clozapine in this patient was determined from two blood levels, one obtained on admission and the second 10.5 hours later. The calculated half-life of 8.11 hours is consistent with published levels for single doses and suggests an apparent stability in clozapine elimination half-life in the face of overdose. The maximum clozapine blood level attained was probably among the highest nonfatal levels reported. The patient recovered fully following hospital admission for monitoring and supportive care. This case report illustrates the usefulness of following the time course of the changes in blood level at selected time intervals, as well as the importance of entertaining a diagnosis of drug overdose in patients presenting with acute mental status changes.