Methadone-related deaths. A ten year overview.

Over the last 10 years we have registered in our district (about 500,000 inhabitants) 36 cases of fatal methadone poisoning, involving both patients on treatment and naive subjects: this is a significant increase of deaths due to methadone use, misuse or abuse compared with previous years. Twenty-four patients (66.7%) were on methadone maintenance programs for heroin detoxification, while 12 (33.3%) were taking the drug without a medical prescription. The average blood concentration of methadone in patients undergoing a maintenance program was 1.06 mg/L (0.21-3.37 mg/L), against 0.79 mg/L (0.2-3.15 mg/L) in those taking the non-prescribed drug. Since 111 heroin-related deaths were recorded in our district in the same period, the fact that there appear to be many methadone deaths (about a third of heroin-related deaths) cannot be overlooked. The aim of this work is to understand the possible reasons for such a large number of methadone-related deaths. On this subject, we have noticed that risks associated with methadone intake are often underestimated by clinicians prescribing the drug: sometimes methadone is prescribed without taking into account patient's tolerance to opiates, and a large number of subjects enrolled in methadone maintenance programs in Italy, have also been given take-home doses, thus increasing the risk of abuse and diversion.