Methadone is a drug that is sometimes prescribed to heroin addicts as a substitute for heroin.
...the danger of patients overdosing on methadone.
methadone in British English
(ˈmɛθəˌdəʊn) or methadon (ˈmɛθəˌdɒn)
noun
a narcotic analgesic drug similar to morphine, used to treat opiate addiction. Formula: C21H27NO
Word origin
C20: from (di)meth(yl) + a(mino) + d(iphenyl) + -one
methadone in American English
(ˈmɛθəˌdoʊn)
noun
a synthetic narcotic drug, C21H27NO, used in medicine to treat heroin and morphine addicts: it is more potent than morphine, with a longer duration of action and milder withdrawal symptoms