Methadone

General Information

Methadone is a morphine substitute first used in Germany in World War II and was made clinically available in the US in 1947. It possess many of pharmacologic properties of morphine and is approximately equipotent as an analgesic when administered parenterally. Unlike morphine, methadone produces marked sedative effects with repeat administration as a result of drug accumulation. This undesirable property restricted clinical usage of the drug until 1965 when methadone was used as narcotic maintenance treatment of former heroin addicts. Although doses of up to 180 mg may be used as maintenance doses, doses of 50 mg or less have been known to be fatal to non-tolerant adults.

Methadone is metabolised largely by mono- and di-N-demethylation with spontaneous cyclization of the resulting unstable metabolites to form EDDP and EMDP. Methadone, EDDP and EMDP are the major urinary excretion products.

Adverse effects of methadone therapy include sedation, dizziness, nausea, weakness, diaphoresis, anorexia, visual disturbances, headache, insomnia, constipation, bradycardia, palpitation and respiratory depression. Overdosage with methadone is characterised by stupor, muscle flaccidity, respiratory depression, cold and clammy skin, pupillary constriction, hypotension, coma and circulatory collapse. Naloxone is considered a specific antidote.

Please note, this assay is for the quantitative determination of methadone in blood. Opiod use (including methadone and its metabolite EDDP and buprenorphine and its metabolite norbuprenorphine) may also be detected via our urinary Drugs of Abuse Screen by LC-MS/MS.