has part has role independent continuant levomethadone dextromethadone opioid analgesic antineoplastic agent xenobiotic organic molecular entity serotonin uptake inhibitor mu-opioid receptor agonist NMDA receptor antagonist racemate anti-HIV agent methadone A racemate comprising equimolar amounts of dextromethadone and levomethadone. It is a opioid analgesic which is used as a painkiller and as a substitute for heroin in the treatment of heroin addiction. CHEBI:6807 environmental contaminant