Methadone deaths: a toxicological analysis.

AIMS: To perform a toxicological analysis of deaths involving methadone and to determine the fatal concentration of methadone in such deaths.
METHODS: Deaths in which methadone was mentioned in the cause of death were identified. Deaths were divided into those associated with methadone only and deaths in which the cause of death was a combination of methadone and other drugs. Toxicological findings in these deaths were analysed and compared with previously published data.
RESULTS: One hundred and eleven cases were analysed. In 55 cases, methadone poisoning was given as the sole cause of death. Fifty victims were adults, age range 17-51 years (median, 23), with five victims under 14 years of age. The mean methadone concentration in the adult deaths was 584 micrograms/litre (median, 435; range, 84-2700). In 56 cases, age range 15-49 years, (median, 28), death was ascribed to a combination of methadone and other drugs. The mean methadone concentration in these deaths was 576 micrograms/litre (median, 294; range, 49-2440). In 26 cases, multiple site sampling was performed. This revealed that there could be a 100% discrepancy between methadone concentrations, and other drugs, in samples collected in different sites in the same body.
CONCLUSIONS: There is an overlap between quoted therapeutic methadone concentrations and methadone concentrations seen in fatalities. However, those dying from methadone poisoning might not be the same as those in a methadone programme. A degree of caution must be exercised in determining a fatal concentration because of the phenomenon of postmortem redistribution. Pathologists and toxicologists need to examine all the available postmortem findings in identifying the cause of death.