A severe case of olanzapine overdose with analytical data

Olanzapine is a second-generation atypical antipsychotic agent approved for the treatment of psychotic disorders and mania. While olanzapine overdoses are common, cases with whole blood concentrations are less so. We describe here a well-documented case of a pure olanzapine overdose in which whole blood concentrations were determined, and compared with other concentrations in the literature.

A 58-year-old woman with a 10-year history of paranoid schizophrenia and poor therapeutic compliance was found unconscious with two empty 28-tablet vials of Zyprexa (olanzapine) 10 mg tablets. Her initial vital signs were blood pressure 110/70 mmHg, pulse rate 82 beats/minute (sinus rhythm), respirations 20 breaths/minute, and the Glasgow Coma Scale score was 7. In the Intensive Care Unit, her pulse rate was 160 beats/minute, in sinus rhythm, and QTc 0.423 seconds (normal <0.4 seconds). Relevant analytical findings were metabolic acidosis, leukocytosis, creatine phosphokinase 1992 mg/dL, and glucose 207 mg/dL. Ten hours after being found, her blood sugar was 350 mg/dL and became normal at 25 hours. The patient needed intubation and insulin.

Olanzapine was detected and quantitated by gas chromatography with nitrogen-phosphorus detector and confirmed by gas chromatography-mass spectrometry using a validated analytical method. At approximately 4, 8, and 12 hours post-ingestion, whole blood concentrations of olanzapine were 0.41, 0.34, and 0.38 mg/L, respectively.

This study reports an acute olanzapine monointoxication with severe toxicity and high whole blood olanzapine concentrations. Clinical and analytical data of similar samples obtained in non-fatal life-threatening cases can be very useful when interpreting postmortem cases.