A postmortem MDMA concentration is not necessarily the concentration that existed at death. After circulation stops, drugs may move between blood, stomach contents, and tissues. A controlled animal study asked an additional question: can alcohol co-exposure change that redistribution?
Liang and colleagues compared rats exposed to MDMA after several weeks of alcohol-water consumption with rats exposed to MDMA without alcohol. After death, the animals were stored under different temperature and humidity conditions for ten days. Blood, body fluids, and multiple tissues were collected at 15 postmortem intervals.
The MDMA dose was 150 mg/kg by intragastric administration, and sampling began soon after dosing. This was a deliberately controlled animal model, not a simulation of an ordinary human recreational dose.
MDMA concentrations changed with postmortem interval, specimen type, co-exposure, and storage conditions. The area under the concentration-versus-postmortem-interval curve was higher in the alcohol-plus-MDMA group than in the MDMA-only group. Lower storage temperature, coupled with lower humidity, reduced the magnitude of the changes.
The pattern was not uniform across specimens. Liver, kidney, spleen, cardiac blood, brain, vitreous humor, and muscle behaved differently. The investigators attributed part of the change to diffusion from drug remaining in the stomach and to movement among blood-rich organs.
Biceps femoris muscle, away from adjacent organs, showed comparatively limited postmortem diffusion in the model. Vitreous humor changed less than some blood-rich tissues but was not completely static. Kidney concentrations were high and potentially affected by urine contamination and enrichment.
“Comparatively stable” does not mean universally preferred. Specimen suitability depends on the compound, collection quality, postmortem interval, preservation, and the question being asked.
The study supports the general principle that postmortem concentration is a dynamic measurement. It also provides a biologically plausible warning that co-existing ethanol may affect distribution or stability. It does not provide a numerical correction factor for human deaths. Species differences, the very high experimental dose, controlled timing, and the storage model limit direct translation.
A forensic toxicologist should therefore avoid working backward from one postmortem MDMA number to a precise antemortem concentration. The interpretation should consider:
Postmortem redistribution can increase, decrease, or otherwise alter a measured concentration over time. Alcohol co-exposure may add another source of variation. A single result can document that MDMA was present, but it may not establish the concentration at death, dose, timing, toxicity, or causal contribution without the rest of the record.
Liang M et al. “How Postmortem Redistribution of MDMA in Acute Alcohol-MDMA Combined-Use Rats Change under Effects of Alcohol.” Scientific Reports (2017). PubMed PMID 28642585; DOI 10.1038/s41598-017-04416-y.