VITREOUS-HUMOR COCAINE AND METABOLITE CONCENTRATIONS - DO POSTMORTEM SPECIMENS REFLECT BLOOD-LEVELS AT THE TIME OF DEATH

The interpretation of postmortem cocaine concentrations is made in an attempt to estimate drug concentrations present at the time of death a nd thus infer not only drug presence but drug toxicity. Previous data suggest that changes in postmortem blood cocaine concentrations over t ime are not predictable and interpretation of cocaine levels should be done with caution. However, these data come from autopsy case series where vital information, such as blood cocaine concentration at the ti me of death, dose and time since last use, and postmortem interval is often not known. The purpose of this study was to characterize postmor tem changes in cocaine and metabolite concentrations relative to premo rtem concentrations over time at two anatomic sites: peripheral blood and vitreous humor, in a controlled, large animal model. Juvenile swin e were given cocaine HCl 10 mg/kg as an IV bolus which resulted in sei zures and wide complex tachycardia. Five minutes after cocaine adminis tration, animals were euthanized. At time of death and eight hours pos tmortem, femoral venous blood and vitreous humor (VH) samples were obt ained for quantitation of cocaine, benzoyl ecgonine (BE), and ecgonine methyl ester (EME) by GC/MS. There were no significant increases over time in mean femoral vein concentrations of cocaine or BE. However, a large interanimal variability in direction and magnitude of concentra tion changes was seen. Mean EME concentrations at the femoral site inc reased significantly over 8 hours (P < 0.03). Mean VH cocaine concentr ations at time of death were significantly lower than corresponding bl ood concentrations (P < 0.02). However, 8 hour postmortem VH cocaine c oncentrations increased in all animals and were similar to the femoral blood concentrations at time of death. These results emphasize the va riability in postmortem cocaine concentrations and the need to conside r the site of collection and postmortem interval as variables in inter preting postmortem cocaine and metabolite concentrations relative to p remortem values.