The effect of postmortem interval on the concentrations of cocaine and cocaethylene in blood and tissues: an experiment using rats.

Cocaine and cocaethylene concentrations in blood and tissues at early stages postmortem (0-6 h) were investigated using alcohol-treated rats. Gas chromatography/mass spectrometry following a liquid/liquid extraction procedure was employed to detect these drugs. Calibration curves showed good linearity in the range of 0 to 2,500 ng/mL with correlation coefficients of 0.9999 and 0.9998 for cocaine and cocaethylene, respectively. In a group treated with cocaine and ethanol orally, the liver lost over 25% of the cocaine present at death after 1 h. Conversely, the hepatic cocaethylene concentrations at this time reached more than twice those at death. Thereafter, the hepatic concentrations of cocaine and cocaethylene were maintained at a constant level until 6 h postmortem. Similar results were obtained with rats given cocaine intramuscularly. No changes in the cocaine and cocaethylene concentrations in any other tissues during the 6-h of postmortem period were observed. The forensic pathologist and toxicologist should be aware of these phenomena when selecting postmortem specimens for the analysis of cocaine and cocaethylene and take them into account when interpreting the results.