The introduction of supervised methadone administration was followed by a reduction in deaths due to methadone overdose in England and Scotland. Deaths related to methadone declined four-fold in both countries, while methadone prescribing increased substantially, between 1993 and 2008.The past two decades have seen rapid growth in methadone prescribing for the management of heroin dependence and widespread adoption of supervised administration of methadone by pharmacists. The authors took the total quantity of methadone prescribed annually, and divided this by 60 mg (the approximate average daily dose) to give an estimate of the number of daily dispensed doses in a given year. This figure was then analysed with the number of deaths identified by coroners as involving methadone (both as the only drug involved, and when methadone was one of a number of substances), between 1993 and 2008. 'The study found that the OD4 index decreased substantially in both Scotland and England despite large increases in methadone prescribing. In England, for example, the OD4 for methadone-only deaths fell from 27.1 in 1993 to 5.8 in 2008, in a period when methadone prescribing increased seven-fold. In Scotland the respective values fell from 19.3 to 3.0 over the same period and methadone prescribing increased 18-fold. The study does not address any other potential cause for the decrease in fatal overdose rates apart from the introduction of supervised methadone dosing. However, it provides good evidence that methadone prescribing has become increasingly safe with the adoption of supervised administration. The OD4 provides a useful tool for monitoring any future changes.'