Abstract
Aims
Limited information exists on characteristics associated with methadone intoxication deaths. We therefore aimed to describe and explore differences in demographics, methadone prescription status, and drug concentrations in deaths with methadone, comparing intoxications with non-intoxications.
Methods
1092 forensic autopsy cases with methadone detected in blood analyzed at Oslo University Hospital (2004–2021) were linked to the Norwegian Cause of Death Registry and the Norwegian Prescribed Drug Registry. Cases were grouped as methadone intoxication (n = 638), other intoxication (n = 252), and non-intoxication (n = 202). Non-parametric tests (Chi-squared, Mann–Whitney U) and logistic regression analyses were used to compare demographic variables, prescription status, and drug concentrations (opioids, benzodiazepines, stimulants, ethanol) between intoxications and non-intoxications.
Results
Methadone prescription was less common in methadone intoxications and other intoxications than in non-intoxications (28.8% and 27.4% vs. 59.9%, respectively; P < 0.001 for both). Methadone intoxications were associated with younger age (adjusted odds ratio [aOR] 0.96; 95% confidence interval [CI] 0.95–0.98) and no recent methadone prescription (aOR 3.01; 95% CI 2.04–4.44) compared with non-intoxications. Adjusted analyses revealed no significant difference in methadone concentration between these groups. However, among cases with prescription, methadone intoxications were associated with higher methadone concentration (aOR 1.20; 95% CI 1.09–1.32). Intoxications also involved more psychoactive drugs and more frequent detections of benzodiazepines and stimulants.
Conclusion
Our results support that the determination of fatal methadone intoxications cannot be based solely on interpretation of postmortem methadone concentrations in blood but is dependent on information about prescription status and degree of tolerance.
Citation
Stine Marie Havig, Gudrun Høiseth, Cecilie Hasselø Thaulow, Henrik Green, Svetlana Ondrasova Skurtveit, Hilde Marie Erøy Edvardsen, Prescription status and drug concentrations in methadone intoxications versus non-intoxications: A registry-linked study of autopsy cases, Forensic Science International, Volume 388, 2026, https://doi.org/10.1016/j.forsciint.2026.113084