Greater THC Lipophilicity Did Not Predict Greater Redistribution in This Series
The investigators expected parent THC to redistribute more than its more polar metabolites, but the observed series did not support that ranking. A chemical-property hypothesis should not be presented as the study’s demonstrated result.
The hypothesis preceded the comparison
The authors proposed that THC’s lipid solubility and distribution characteristics would favor greater postmortem redistribution than 11-hydroxy-THC or THC-COOH. They then measured central and peripheral blood in nineteen selected human death cases. Median central-to-peripheral ratios were approximately 1.5, 1.7 and 1.8, respectively.
The observations did not confirm the predicted order
The report explicitly stated that the parent-versus-metabolite hypothesis was unsupported. That does not establish the reverse ranking as a precise universal law. Ratios varied widely, sample availability differed by analyte, and central-peripheral comparisons were not significant for every compound. A descriptive median is not an individual reconstruction coefficient.
Mechanistic plausibility needs empirical limits
Physicochemical properties can help formulate questions, but they cannot replace actual postmortem data. The study was observational, lacked a known controlled dose and had only three antemortem comparisons. Its findings do not establish a concentration at the time of use, degree of impairment or causal contribution to death. Those conclusions require evidence beyond a lipophilicity argument.
Related analysis: the limits of central-to-peripheral ratios.
Research cited
Holland and colleagues (2011). Postmortem redistribution of THC, 11-hydroxy-THC, and THCCOOH. DOI: 10.1016/j.forsciint.2011.06.028.
