To the Editor: Several reports in the literature have noted the favorable risk-benefit profile of quetiapine, an atypical antipsychotic used in the treatment of schizophrenia. The main clinical findings in quetiapine overdose—resulting from α-adrenergic and histamine receptor blockade—are hypotension, tachycardia, and somnolence. Potentially life-threatening consequences from overdose include QT prolongation and respiratory depression. To our knowledge, overdoses ranging from 1,200 mg to 20,000 mg have not yet been noted to result in fatalities. We report here what we believe is the first fatality associated with an overdose of quetiapine.

To the best of our knowledge, this is the first report of a death associated with an overdose of quetiapine. Quetiapine overdose, alone or in combination with other medications, has resulted in QT prolongation (1), loss of consciousness (2), sinus tachycardia (3), and hypokalemia with first-degree heart block (4). All of the patients in these reports recovered with symptomatic and supportive treatment, including one patient with an overdose as high as 20,000 mg, which resulted in serum levels of 12,700 ng/ml (3). Factors possibly contributing to the death of our patient were a history of cardiac dysrhythmia and hypertensive heart disease. There was no evidence to suggest overdosing with medications other than quetiapine. Drug interactions did not appear to play a significant role in toxicity. Hence, despite quetiapine’s safety record in overdose, medical comorbidity in extreme overdoses may contribute to a fatal outcome.