The article presents a study of forensic autopsy cases in Norway where methadone was detected in the blood, comparing deaths where (1) methadone was assessed as the cause of death and (2) deaths where other drugs or other causes were responsible. The study included 1,092 autopsy cases from 2004 to 2021, linked to the Cause of Death Registry and the Prescription Database. The cases were divided into three groups: methadone intoxication, other intoxication, and non-intoxication.
The main finding is that people who died of methadone intoxication more often had not received methadone on prescription during the last six months before death, compared with people who died from other causes. This may indicate the use of methadone outside of prescribed treatment, possible resale/leakage from opioid agonist therapy programs, and lower tolerance in some users.
An important point is that the methadone concentration in blood alone did not clearly distinguish between fatal methadone poisonings and deaths from other causes. This supports that tolerance, prescription status, and clinical/contextual information are crucial when assessing whether methadone was actually the cause of death.
The study also found that many deaths involved multiple psychoactive substances, particularly benzodiazepines/Z-hypnotics and central stimulants. This highlights that overdoses are often complex and that combined drug use may play an important role in fatal methadone poisonings.