It was interesting to see the issue of whether dosage of methadone affected the use of additional drugs raised in the Bulletin most recently by Kernan & Scully (Psychiatric Bulletin, June 2006, 30, 234). Although many clinicians are reluctant to prescribe high doses of methadone, the evidence does seem clear that heroin use tends to decline as methadone increases.

This is a substitution approach, but patients on methadone programmes can develop as many problems from ongoing cocaine as from heroin use (notably financial and psychiatric problems). This appears to be widespread (Reference Gossop, Marsden and StewartGossop et al, 2002), and in two related investigations of our own patients undergoing opioid substitution (n=57 and n=72) cocaine was used by many of the 77% of patients showing some additional drug in their urine. Abstinence from substance use was related to female gender (χ²=0.62, d.f.=1, P<0.1), type of substitute medication (χ²=6.8, d.f.=2, P<0.05) and being longer in treatment (t=1.61, P<0.1), but for overall drug use the dosage of maintenance agent had no effect. For cocaine this was one of the weakest relationships (χ²=0.2, d.f.=1, P40.1).

Outcomes in maintenance treatment are usually related to limiting heroin use, and the fallback measure of increasing methadone to achieve this has been attractive. We believe that the frequent use of cocaine among this population will render methadone treatment much less straightforward, with more requirements for additional behavioural treatments (Reference Schottenfeld, Chawarski and PakesSchottenfeld et al, 2005).