UNDER REVIEW (September 2016)
Mechanism of Action:
Methadone is a synthetic opioid analgesic with similar mechanism of action to that of morphine (mu opioid receptor agonist). Because of its slow metabolism and very high lipid solubility, methadone is longer lasting than morphine-based drugs. Methadone has a typical half life of 24 hours or more, permitting administration only once a day in heroin detoxification and maintenance programs. Methadone is almost as effective when administered orally as by injection. Tolerance and dependence may develop, and withdrawal symptoms, though they develop more slowly and are less acutely severe than those of morphine and heroin, are more prolonged.