Assessing free and total morphine following heroin overdose when complicated by the presence of toxic amitriptyline levels.

A 43-year-old female was reported to inject heroin, which led to her rapid death. Because of the potential for criminal charges, laboratory results that could verify "hotshot" heroin overdose were valuable. Initial toxicological analysis detected morphine (0.78 mg/L), amitriptyline (2.91 mg/L), and nortriptyline (2.80 mg/L) in femoral blood. Because these tricyclic antidepressant levels alone might normally be associated with a fatal outcome, the ratio of free versus total morphine (88.6%) and presence of 6-monoacetylmorphine in vitreous fluid were used support a history of rapid death following intravenous (IV) administration. The distribution of amitriptyline and nortriptyline was consistent with accumulation of drug after chronic dosing. Our other results suggest that the low morphine level in vitreous humor fluid (0.16 mg/L) relative to free morphine in femoral blood (0.78 mg/L) may also be an indicator of limited survival time following exposure to morphine. Based upon comprehensive toxicologic analysis, we determined overdose due to IV abuse of heroin was likely to have precipitated the fatal outcome. This case underscores the need for complete toxicologic workup and to consider individual variation in the dose response during toxicologic interpretation of postmortem results.