Characterization of methadone overdose: clinical considerations and the scientific evidence.

Overdosing with methadone is a growing phenomenon in Britain and other countries due to the increase in prescription and the availability of this compound. Little is known of the circumstances surrounding methadone death due to some extent to the difficulty of defining drug-related death and also the difficulty of collecting clinical and biographical data in a predominantly illegal and marginal milieu. However, the evidence points to highest risk at night (to this end manifestations of its toxicity often go unrecognized) in those whose usual tolerance has been reduced and occurring some considerable time after ingestion. Further investigations are needed to elucidate fully the mechanism and spectrum of methadone overdose. Death from methadone is eminently preventable more so because of the long-term nature of the clinical sequelae. Indeed the key issue with methadone that sets it apart from other opioids is its potential for delayed toxicity. Consequently steps should be taken to disseminate the salient facts to all those who come into contact with the drug.