Postmortem Redistribution of Tetrahydrocannabinol: A Data Reconstruction Comparison of Controlled Animal Models and Human Casework

Abstract

Postmortem redistribution of tetrahydrocannabinol (THC) remains controversial because controlled animal experiments often show pronounced central-to-peripheral concentration gradients, whereas human casework exhibits highly variable patterns. This study applied retrospective data reconstruction to compare the central-to-peripheral blood ratio of THC and its metabolites between animal models and human forensic casework and to test whether postmortem interval explains the observed variability. A raw dataset was reconstructed from peer-reviewed literature, comprising paired central and peripheral measurements from porcine and rabbit models and a large set of paired measurements from autopsy caseworks. Central-to-peripheral ratios were calculated from matched cardiac and femoral blood concentrations, and nonparametric group comparisons and correlation analyses were performed. Animal models showed consistently elevated central-to-peripheral ratios, whereas human casework clustered near unity with frequent values below 1.0. In animal models, postmortem interval was strongly associated with increasing central-to-peripheral ratio, but no such relationship was observed in human casework. In contrast to THC, the central-to-peripheral ratio for the major carboxy metabolite was near 1.0 in both cohorts. These findings indicate that controlled animal models may overestimate the magnitude and predictability of postmortem redistribution for THC in real-world forensic settings and support interpretation strategies that prioritize peripheral sampling and metabolite context when assessing postmortem cannabinoid results.

Keywords

• Postmortem redistribution
• Tetrahydrocannabinol
• Animal models
• Autopsy
• Forensic toxicology
• Data reconstruction

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