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Methadone, a long-acting oral opioid agonist, was first used to treat
opioid dependence in the United States in 1964, and was introduced
into Australia in 1969. While countries such as the United Kingdom
have also shown interest in the use of methadone for heroin
withdrawal, Australia has more commonly used it as a maintenance
therapy. Currently, there are around 23 000 clients in methadone
treatment throughout Australia, and this number is growing at around
15% per annum.
Methadone treatment is the main clinical response to heroin
addiction in Australia. Randomised controlled trials and
controlled observational studies have shown methadone to be
effective in reducing heroin use.1 Methadone treatment has
also been found to be effective in reducing criminality, the risk of
contracting HIV infection and the risk of deaths from overdose, and is
associated with improvements in health and social
functioning.1
The report by Caplehorn and Drummer in this issue of the Journal reminds us that, as with all medical treatments,
there are risks associated with methadone treatment.2 Looking at
deaths associated with New South Wales methadone maintenance
programs in 1994, the authors identified two problem areas -- the
period of induction into methadone treatment and the diversion of
methadone to non-treatment populations. Despite the mortality
associated with methadone maintenance treatment, Caplehorn and
Drummer estimate that the New South Wales program saved 68 lives in
1994.
The risk of overdose during induction into methadone therapy can be
reduced by better training of prescribers in assessing the degree of
opioid dependence and tolerance. These skills are now included in
learning objectives developed at the request of the National
Methadone Committee,3
and methods for assessing prescribers'
competence in this area are currently being developed by an expert
group (Robert Hughes, Director, National Drug Strategy, Drug
Strategy and Population Health, Social Marketing Branch, Public
Health Division, Department of Health and Aged Care, Canberra, ACT,
personal communication). Routine regular monitoring for signs of
intoxication and withdrawal is also an important consideration, and
shared care protocols to improve the relationship and communication
between prescribers and dispensers of methadone during patients'
induction phase are under development in several jurisdictions --
such protocols need national consistency.
In Australia, contention persists among clinicians and
policymakers about the most appropriate dosing regimen for
initiating methadone therapy. The dosing range and recommended
increments in the first weeks of methadone treatment set out in the
current National policy on methadone treatment4 have been
criticised for being too rigid and not able to take account of
variation in "real-world" practice. At the National Methadone
Conference (Melbourne, 21-23 November, 1996), prescribers argued
that inadequate starting doses will drive patients who experience
withdrawal symptoms to "top up" the prescribed dose of methadone with
heroin, benzodiazepines or illicit methadone. Thus, there is a need
to find a balance between effective dosing while minimising the risk
of overdose, and allowing flexibility in clinical judgement.
To maintain the good reputation of methadone programs in Australia,
it is crucial to establish credible guidelines on safe and effective
induction into methadone treatment. To that end, a meeting to be held
in early 1999 aims to establish evidence-based guidelines. This
scientific review should provide a useful framework for informing
the development of policy for induction, stabilisation and
assessment of patients in methadone treatment.
Illicit methadone use has been found to be widespread both overseas
and in Australia.5 The most common reason
reported for this use has been self-treatment of opiate
withdrawal.6 Rarely, users report using
methadone for its euphoric effects, and this is much more likely if the
methadone is injected.7 There have been a variety of
approaches to limiting the potential for diversion of methadone
supplies. For example, in South Australia, the volume of takeaway
doses is expanded to up to 100 mL to reduce the likelihood of injection.
Other States have limited the timing and numbers of takeaway doses. A
systematic review of these approaches is required to determine the
most effective way of responding to this problem.
In view of the mortality associated with methadone maintenance
treatment highlighted in this issue of the Journal,2 there is a risk
that there will be calls for further restrictions on methadone
availability. While this may reduce the number of methadone-related
deaths, it may inadvertently lead to an increase in the number of
heroin-related deaths. Thus, it seems that the important lesson in
methadone-related mortality is that we must ensure that both
prescribers and potential users of methadone are aware of the risks of
overdose, particularly for those who are not opioid tolerant.
Robert L Ali
Chair, National Expert Advisory Committee on Illicit Drugs
Adelaide, SA
Allan J Quigley
Director, Clinical Research and Policy Development
WA Alcohol & Drug
Authority, Perth, WA
- Ward J, Mattick RP, Hall W. Methadone maintenance treatment and
other opioid replacement therapies. Amsterdam: Harwood Academic
Publishers, 1998.
-
Caplehorn JRM, Drummer OH. Mortality associated with NSW
methadone programs in 1994: lives lost and saved. Med J Aust
1999; 170: 104-108.
-
Allsop S, Bell J, Brough R, et al. Learning objectives for methadone
prescribers. Canberra: AGPS, 1997.
-
National Drug Strategy. National policy on methadone treatment.
Canberra: AGPS 1997.
-
Darke S, Ross J, Hall W. Prevalence and correlates of the injection
of methadone syrup in Sydney, Australia. Drug Alcohol Depend
1996; 43: 191-198.
-
McLellan AT. Methadone diversion in the USA (1998). In: Hall W,
editor. Proceedings of an international opioid overdose symposium.
Sydney: National Drug & Alcohol Research Centre, 1998. (Monograph
No. 35.)
-
Darke S, Hall W. Levels and correlates of polydrug use among heroin
users and regular amphetamine users. Drug Alcohol Depend
1995; 39: 231-235.
©MJA 1998
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