Fatal unintentional overdose of diltiazem with antemortem and postmortem values.

Background: Therapeutic errors involving calcium channel antagonists (CCA) resulting in death rarely have been reported in detail. We report a fatality from an unintentional overdose of sustained-release (SR) diltiazem including antemortem and postmortem blood concentrations.

Case Report: A 65-year-old man with aortic stenosis mistakenly took six tablets of diltiazem 360 mg SR. He developed symptoms of toxicity by 7 hours after ingestion. By 10 hours, he went to the emergency department. Despite a prolonged resuscitative attempt, the patient died 17 hours postingestion. An antemortem blood sample drawn 11.5 hours after ingestion was 2.9 mcg/mL. Postmortem gas chromatography of central blood revealed a diltiazem level of 6 mcg/mL and the peripheral blood sample measured 5 mcg/ mL.

Conclusion: This case suggests that an unintentional overdose with a CCA may be lethal if the patient's cardiovascular ability to compensate for the toxic effects is compromised.