A synthetic opioid that is used as the hydrochloride. It is an opioid analgesic that is primarily a mu-opioid agonist. It has actions and uses similar to those of MORPHINE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1082-3)

A synthetic opioid with analgesic activity. Methadone mimics the actions of endogenous peptides at CNS opioid receptors, primarily on the mu-receptor and has actions similar to those of morphine and morphine-like agents. The characteristic morphine-like effects include analgesia, euphoria, sedation, respiratory depression, miosis, bradycardia and physical dependence. However, the detoxification symptoms between morphine-like agents and methadone differ in that the onset of methadone's withdrawal symptoms is slower, the course is more prolonged and the symptoms are less severe.

Synthetic narcotic possessing pharmacologic actions similar to those of morphine and heroin and almost equal addiction liability; used as an analgesic and as a narcotic abstinence syndrome suppressant in the treatment of heroin addition.

Methadone, potent synthetic narcotic drug that is the most effective form of treatment for addiction to heroin and other narcotics. Methadone first became available at the end of World War II. Similar to morphine in its analgesic effect, it was originally used in medicine to alleviate severe pain.