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Letters

Treatment should be tailored for each patient

BMJ 1995; 310 doi: https://doi.org/10.1136/bmj.310.6977.463b (Published 18 February 1995) Cite this as: BMJ 1995;310:463
  1. Kim Wolff,
  2. Alastair Hay,
  3. Duncan Raistrick
  1. Research fellow Reader in chemical pathology Research School of Medicine, Leeds University, Leeds LS2 9TJ
  2. Consultant Leeds Addiction Unit, Leeds LS2 9NG

    EDITOR,—Michael Farrell and colleagues note that for successful maintenance treatment of people dependent on opiates high doses of methadone are needed, and they recommend a dose of 70-120 mg a day.1 High doses are essential for people with chronic dependence, particularly long term injecting misusers, who may use more than one drug, but it is doubtful whether extended treatment with high doses is suitable for people who smoke heroin and who meet the criteria for substitute prescribing. When heroin is smoked or inhaled (rather than injected) the equivalent daily methadone dose can be reduced by roughly one third. In our experience with people who smoke heroin lower doses of methadone (30-60 mg/day) prevent withdrawal symptoms and relapse.

    Tailoring treatment to suit the individual person is essential. Providing a suitable dosage schedule is difficult because the patient's reported drug use has to be balanced against a clinical assessment of his or her dependence. A rigid conversion system (illicit heroin versus pharmacologically pure methadone) is not possible because of the fluctuating purity of illicit heroin.

    Many variables have been investigated to help assess the efficacy of maintenance treatment with methadone. The usual procedure entails analysis of urine for durgs of misuse. Although important for assessing use of non-prescribed drugs, analysis of urine sheds no light on compliance with methadone maintenance. At present most doctors or agencies who prescribe methadone do not monitor compliance. This is despite the fact that in Britain a substantial quantity of methadone is diverted to illegal sources, with a resultant increased risk of unsupervised or unauthorised consumption of methadone by people who have never used opiates.2 3

    We believe that it is essential to know whether patients are taking all of their prescribed treatment, diverting a proportion of it, or supplementing the prescription. Scientific measurements are needed to test compliance; we have reported elsewhere that measurements of plasma methadone concentration meet this need.4 In one study we compared consumption of methadone by patients on the site at Leeds Addiction Unit with that by patients obtaining their prescription from a pharmacy. Compliance was assessed by measuring the plasma methadone concentration under steady state conditions. Patients who consumed methadone on site were substantially more compliant than those who consumed it off the site. Those who consumed it off the site did so at times other than those indicated on the prescription or consumed several days' supply at one time. Patients from both groups supplemented their prescription with methadone obtained illicitly.5

    As a result of our work on compliance we believe that measurement of the plasma methadone concentration provides important information for clinicians and should be a routine part of substitute prescribing.

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