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.
Keywords: Blood levels; Death; Maintenance; Methadone.
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