Overdose of Ziprasidone

Ms. A, a 38-year-old woman with psychosis, was admitted to the emergency department 1 hour after ingesting 4020 mg of ziprasidone. Her current medications included 100 mg of quetiapine at bedtime, 900 mg/day of gabapentin, 300 mg/day of venlafaxine, metformin, rofecoxib, and pravastatin. She reported that she had taken no additional doses of these medications, had not used alcohol, and had not vomited. She was alert and oriented and had a Glascow Coma Scale (4) score of 15. No abnormalities were found in her laboratory test values; she was afebrile and had stable vital signs. Cardiac monitoring revealed a sinus rhythm. Charcoal and gastric lavage were initiated.

Six hours after Ms. A’s ingestion, an ECG showed borderline intraventricular conduction delay (QRS duration=111 msec). No comparison ECGs were available; no repeat ECGs were performed. Ms. A’s QT interval was 395 msec; her QTc interval was 445 msec. She oscillated between being drowsy and calm, and alert and agitated. Her blood pressure dropped from 129/81 mm Hg at admission to 99/34 mm Hg 4 hours later. Her temperature, pulse rate, and respiration rate all remained normal. Although her blood pressure eventually returned to normal, it averaged 106/45 mm Hg over a 14-hour period. Ms. A experienced diarrhea and urinary retention.