Time- and temperature-dependent postmortem △9-tetrahydrocannabinol concentration changes in rabbits following controlled inhaled cannabis administration

Postmortem redistribution (PMR), a well-known phenomenon in forensic toxicology, can result in substantial changes in drug concentrations after death, depending on the chemical characteristics of the drug, blood collection site, storage conditions of the body and postmortem interval (PMI). Limited PMR data are available for Delta(9)-tetrahydrocannabinol (THC), the primary psychoactive component in Cannabis sativa. PMR was evaluated after controlled cannabis inhalation via a smoking machine and exposure chamber in New Zealand white rabbits. Necropsies were performed on five control rabbits immediately after euthanasia, whereas 27 others were stored at room temperature (21(degrees)C) or refrigerated conditions (4(degrees)C) until necropsy at 2, 6, 16, 24 or 36 h after death. THC and its Phase I and glucuronidated Phase II metabolites were quantified in blood, vitreous humor, urine, bile and tissues by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Under refrigerated temperature, heart blood THC concentrations significantly increased at PMI 2 h in rabbits, whereas peripheral blood THC concentrations showed a significant increase at PMI 16 h. Central:peripheral blood and liver:peripheral blood ratios for THC ranged from 0.13 to 4.1 and 0.28 to 8.9, respectively. Lung revealed the highest THC concentrations, while brain and liver exhibited the most stable THC concentrations over time. This report contributes much needed data to our understanding of postmortem THC behavior and can aid toxicologists in the interpretation of THC concentrations in medicolegal death investigations.

Automated summary

Postmortem redistribution (PMR) is a well-known phenomenon that can cause significant changes in drug concentrations after death due to various factors. This study evaluated PMR of THC in rabbits and found that refrigerated temperature led to an increase in THC concentrations in heart blood at 2 hours postmortem, while peripheral blood showed an increase at 16 hours postmortem. Lung had the highest THC concentrations, while brain and liver exhibited stable concentrations over time. This study provides valuable data for understanding postmortem THC behavior and can help toxicologists interpret THC concentrations in forensic death investigations.