Methadone starting doses may be too low
The history of methadone maintenance treatment, from its early days of controversy through the development of ‘respectability' to the overwhelming evidence base in support of its effectiveness, has resulted in the development of guidance-based practice. This includes the limitation of starting doses to between 20 and 40 mg daily to reduce the possibility of toxicity during the first two weeks of treatment.
In stark contrast to accepted methadone induction policy in the UK, Bakker and Fazey argue that low starting doses may paradoxically increase risk through under-treatment and the resulting use of illicit drugs by patients on top of prescribed medication.
The authors present a set of individual case studies, detailing 141 treatment starts on 121 patients over a ten-year period, all by ‘testing methadone tolerance'.
The paper describes a very individualistic methadone dose induction regimen. In this process, new patients who have previously taken methadone and found the dose that holds them are given this dose from the start.
The patient is given advice and information about methadone and toxicity, has the first dose supervised by a local pharmacist, and then returns to the health centre for observation for toxicity. Prescribing continues with supervised consumption and regular clinical review.
The median starting dose was 70mg, with 23 patients receiving initial doses of 100mg or more. The authors reported no methadone toxicity or related deaths throughout the case series.
The paper highlights the effectiveness of methadone maintenance treatment in reducing a range of drug-related morbidities, and challenges accepted practice in the area of dose induction.
Acknowledging the small size of their sample, the authors recommend a rigorous trial to compare methadone tolerance testing with conventional induction methods.
Others have advised caution in extrapolating the findings and practice to the wider treatment environment, and have expressed fears of unnecessary treatment-related deaths should the process be adopted elsewhere.
GPs may either be attracted by the challenge and openness of the debate on starting doses, or may be reminded of the potential dangers attached to methadone induction.Reviewer
Dr Jez Thompson
Former GP, Clinical Director, Leeds Community Drug Services