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Updated: Dec 21, 2025
Administration of Δ9-Tetrahydrocannabinol (THC) in Adolescent and Adult Mice
Published on: August 1, 2025
Time-Dependent Changes in THC Concentrations in Deceased Persons
Mark Chu1,2, Matthew Di Rago1,2, Dylan Mantinieks1,2
1Department of Forensic Medicine, Victorian Institute of Forensic Medicine, 65 Kavanagh Street, Southbank, Victoria 3006, Australia.
Insights
Postmortem blood analysis reveals significant increases in delta-9-tetrahydrocannabinol (THC) concentrations shortly after death, followed by a decline. These dynamic changes in THC levels complicate interpretation of forensic toxicology results.
Area of Science:
- Forensic Toxicology
- Postmortem Chemistry
- Cannabinoid Analysis
Background:
- Accurate interpretation of postmortem toxicology is crucial for forensic investigations.
- Delta-9-tetrahydrocannabinol (THC) is the primary psychoactive component of cannabis.
- Understanding postmortem changes in drug concentrations is essential for reliable results.
Purpose of the Study:
- To investigate the changes in delta-9-tetrahydrocannabinol (THC) blood concentrations during the postmortem period.
- To compare THC levels in antemortem, mortuary admission, and autopsy blood specimens.
- To assess the impact of postmortem interval on THC concentrations.
Main Methods:
- Comparison of THC concentrations in blood samples collected at different time points: antemortem, upon body admission to the mortuary (AD), and at autopsy (PM).
- Analysis of 239 AD, 106 autopsy, and 147 antemortem specimens.
- Inclusion of 14 cases with all three specimen types from the same decedent.
- Comparison with acetaminophen to control for postmortem interval effects.
Main Results:
- Median THC concentration in AD blood was 13.7 ng/mL, autopsy blood was 13.8 ng/mL, and antemortem blood was 1.9 ng/mL.
- In cases with all three specimens, median concentrations were: antemortem 4.0 ng/mL, AD 15.5 ng/mL, and PM 4.4 ng/mL.
- Significant increases in THC were observed in the early postmortem period, followed by a decline.
- Acetaminophen showed no significant change in blood concentration postmortem.
Conclusions:
- THC blood concentrations exhibit dynamic changes in the early postmortem period, increasing and then declining.
- While median autopsy concentrations were similar to antemortem levels, the transient increase complicates interpretation.
- Variability in THC concentrations across different postmortem sampling sites (femoral, subclavian, heart) showed no significant overall difference.
- These findings highlight the challenges in interpreting postmortem THC concentrations due to complex postmortem phenomena.
Abstract:
Changes in the concentrations of Δ9-tetrahydrocannabinol (THC) in the postmortem period were investigated in a series of cases by comparing concentrations in blood taken on receipt of the body in the mortuary (admission specimen, AD) with the concentrations obtained in blood taken at autopsy some time later and also from blood specimens taken antemortem. Overall, the median THC concentration in AD blood was 13.7 ng/mL (n = 239, range LOQ-220), while the median concentration at autopsy was 13.8 ng/mL (n = 106, range LOQ-810) and 1.9 ng/mL (n = 147, range LOQ-48) antemortem. Fourteen cases had all three specimens taken from the same decedent. The corresponding AM, AD and PM median concentrations were 4.0 (range LOQ-48), 15.5 (range 4.0-176) and 4.4 ng/mL (LOQ-56), respectively. The median elapsed times from AM to AD and AD to PM were 33 and 97.5 h, respectively. In contrast, acetaminophen showed no change in blood concentration from AM to AD (6.8 and 6.0 mg/L, respectively). These data show large increases in THC concentration in the early postmortem period, followed by a decline, although the median blood concentrations at autopsy were similar to that obtained antemortem. In contrast, when blood was taken from the femoral region, subclavian and heart ventricles sites, in the same case, the THC concentrations, while variable, showed overall no significant difference. These dynamic changes reflect complex phenomenon occurring in deceased persons and will further serve to increase the uncertainty over any interpretation of postmortem THC concentrations.
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