How much seroquel does it take to overdose?

Mr. A was a 52-year-old white man with chronic paranoid schizophrenia and a history significant for multiple psychiatric hospitalizations, poor response to neuroleptic therapy, and irregular medication compliance. His history was also significant for overdosing, usually during attempts at self-adjustment of medications. After an overdose of risperidone in the past, he was noted to have a QT interval of 496 msec. Mr. A's medical history was significant for cardiac dysrhythmia and hypertension, which were managed with felodipine, 10 mg/day. His psychiatric medications were 600 mg/day of quetiapine, 100 mg/day of sertraline, 20 mg of buspirone t.i.d., and 50 mg of haloperidol decanoate by intramuscular injection every 2 weeks. On the day of the overdose, Mr. A was discovered to be comatose, presumably a few hours after ingestion of the quetiapine, and in acute respiratory distress. Resuscitation efforts by paramedics were unsuccessful. An autopsy revealed cardiomegaly, with left ventricular hypertrophy and bilateral pulmonary congestion. Further testing revealed quetiapine and nicotine in his urine and a negative immunoassay screening test for his other medications. Mr. A's serum quetiapine level was 18,300 ng/ml (steady-state expected range: 100-1,000 ng/ml). Quetiapine was also detected in his gastric contents. Calculation of pill ingestion from pharmacy records of his last refill, based on an assumption of regular medication compliance, estimated his overdose at approximately 10,800 mg of quetiapine