In cases where more than one drug is used, the drug responsible for death due to overdose is difficult to establish. Moreover, the same drug prescribed by physicians can also be bought on the street. In seventy percent of the deaths due to overdose studied in Glasgow and Edinburgh a combination of different drugs was found (3).

Prescribed drugs such as temazepam were often encountered in deaths in Glasgow. However, among only 14 of the 34 persons who died in 1992 and where temazepam was found, this was prescribed by their physician. Because of the presence of other drugs it is not clear whether temazepam really caused the death of these people. Probably the combination of these different drugs was fatal to them. This was also the case with the methadone deaths in Edinburgh. However, in Edinburgh, the authors could not determine whether methadone was prescribed or not. Both Hammersley and Obafunwa report that heroin/morphine deaths seldom occur in Edinburgh (4). 'The fall of the deaths due to overdose in the Lothian and Borders Region of Scotland (LBRS) after 1984 reflects in part the strict policing that took place, in particular in the Edinburgh area'.

'The increase of methadone deaths is probably due to the introduction of a street trend to use this agent as a substitute to heroin.' The author suggests that methadone deaths are mainly caused by the use of illicit methadone.

Therefore, these figures suggest that participants of methadone programmes are at lower risk of death due to overdose. However, this does not mean that methadone is an innocent substance. The high and increasing number of methadone deaths in Britain is alarming and certainly needs more attention. The first priority should be to establish whether the methadone causing death has been prescribed within a methadone programme or bought on the street. It also should be evaluated at what point during the course of the methadone programme death takes place. Further instruction doctors prescribing methadone could be necessary. The use of non-prescribed methadone without medical supervision can lead to high risks, especially when it is used as a substitute for heroin in order to get a 'high' instead of to prevent withdrawal symptoms. Physicians have to be aware of this danger and they should make sure that the prescribed methadone (as well as other psycho-active drugs) does not end up in the 'grey market'.