Definition

The hydrochloride salt of methadone, a synthetic opioid with analgesic activity. Similar to morphine and other morphine-like agents, methadone mimics the actions of endogenous peptides at CNS opioid receptors, primarily the mu-receptor, resulting in characteristic morphine-like effects including analgesia, euphoria, sedation, respiratory depression, miosis, bradycardia and physical dependence. Because of the prolonged half-life of merthadone compared to other morphine-like agents such as heroin, the onset of opiate withdrawal symptoms is slower, the duration of opiate withdrawal is prolonged, and opiate wihdrawal symptoms are less severe.