Since cocaine in blood rapidly hydrolyzes to benzoylecgonine, cocaine concentrations determined in postmortem blood may not reflect the presence or concentration of cocaine in the body at the time of death. The interpretative value of the determination of cocaine and benzoylecgonine in brain tissue was investigated. Cocaine and benzoylecgonine were quantitated by coextraction and formation of the propyl derivative of benzoylecgonine followed by selected ion monitoring gas chromatography/mass spectrometry (GC/MS) using electron ion impact ionization. Cocaine and benzoylecgonine were found to be evenly distributed throughout the brain. Cocaine and benzoylecgonine concentrations were stable in frozen brain tissue (−4°C) on reanalysis after 1 to 3 months of storage, and in refrigerated tissue (10°C) after 30 days of storage. Blood, brain, and liver concentrations of cocaine and benzoylecgonine in 37 cocaine overdose cases and 46 cases in which cocaine was incidental to the cause of death were reviewed. The ratios of cocaine/benzoylecgonine in the toxic cases (brain mean 14.7 and blood mean 0.64) were clearly different from those found in the incidental cases (brain mean 0.87 and blood mean 0.27). The brain/blood ratios of cocaine and benzoylecgonine concentrations generally were characteristic of the time elapsed since cocaine dosing. In cocaine overdose cases, the mean ratio was 9.6 for cocaine and 0.36 for benzoylecgonine. These are within the range found in animal studies for brain/blood ratios of cocaine and benzoylecgonine 0.5 to 2 h after cocaine administration. In incidental cases, the brain/blood ratios were mean 2.5 for cocaine and 1.4 for benzoylecgonine. These ratios confirm the accumulation of benzoylecgonine in brain tissue and its persistence in the body after disappearance of the parent drug.

The attempt to explain the pathophysiology of deaths from intravenously administered narcotics has been hindered in the past because of the small number of fatal cases reported annually in most areas of the United States and relatively insensitive toxicological methods. A sudden and dramatic increase in deaths attributed to intravenously administered narcotics together with improved and sensitive methods for the identification and quantitation of the major metabolite of heroin in tissues have provided the forensic pathologist with the necessary tools to re-evaluate this type of fatality.

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