Fatal cyclobenzaprine overdose with postmortem values

There are only two published cases of overdose with postmortem blood cyclobenzaprine concentrations, both with confounding factors. We report two additional cases of fatal cyclobenzaprine overdose with postmortem values. Case 1: a 56-year-old female was found in full cardiopulmonary arrest after a verbal suicide threat to a friend. Postmortem blood concentrations were cyclobenzaprine 0.96 mg/L and diazepam 0.3 mg/L. Case 2: a 37-year-old male was found in full arrest by a family member after an intentional ingestion of cyclobenzaprine. Postmortem blood concentrations were cyclobenzaprine 0.8 mg/L and ethanol 0.174 gm/dL. The concentrations of diazepam and ethanol reported in these two patients were not found in quantities usually associated with a fatal outcome, suggesting that the cyclobenzaprine was the primary cause of the fatality. Additionally, the blood was drawn from a femoral site, so that postmortem redistribution is not a likely factor. Blood concentration of > or = 0.8 mg/L cyclobenzaprine may be associated with a fatal outcome.