Wednesday, March 17, 2010

Methadone Maintenance Program of BC

The College of Physicians and Surgeons of British Columbia administers the Methadone Maintenance Program under the authority of the Health Professions Act in accordance with Health Canada's Drug Strategy and Controlled Substances Program.

Methadone was discovered in 1938 by German scientists, Bockmuhl and Ehrhart. In 1947, Harris Bell and colleagues found that it was beneficial in treatment of opiate dependent patients.

Ingeborg Paulus and Dr. Robert Halliday, working with the Narcotic Addiction Foundation in Vancouver established the first methadone maintenance treatment program in the world. Their results were published in the CMAJ 1967.

Since then many studies have shown physical, mental and social benefits for patient on methadone maintenance and consistently a reduced risk of communicable infection for those participating in methadone maintenance programs. There is a 3 to 4 fold increase in death rates for those discontinuing methadone maintenance. This latter figure is related to the high risks of illegal IV drug use.

Because methadone is a controlled substance, physicians prescribing must have authorization from the federal Minister of Health. Full authorization in BC requires training in methadone workshops, preceptorship with a physician approved by the MMP, review of prescribing profile of the clinician, interview by the College staff, continued medical education in addiction medicine, willingness to be on call, and agreement to undergo peer review within the first year.

Methadone is a long acting synthetic opioid that is primarily a mu receptor agonist. The half life of the drug is extremely variable averaging 24 t0 36 hours at steady state but ranging from 9 to 90 hours. As a result of the long half life methadone may accumulate. It takes 4 to 5 days for methadone plasma levels to reach steady state. Methadone metabolism is primarily by liver enzymes involving cytochrome P450. Because many drugs can act on this site there are significant drug interactions.

Information for the above is found in the Methadone Maintenance Handbook, December 2009, a publication of the College of Physicians and Surgeons of British Columbia.

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