A dose-response comparison between methadone and morphine self-administration.
Rats were allowed to self-administer a solution of 0.9% saline, or 0.01, 0.03, 0.1 or 0.3 mg/kg/infusion of methadone hydrochloride or 0.03, 0.1 or 0.3 mg/kg/infusion of morphine sulfate. The results showed that number of infusions taken was an inverse function of unit dose, while amount of drug self-administered (mg/kg) was a direct function of unit dose. The data also indicated that more morphine than methadone was self-administered.
D000818:Animals; D003216:Conditioning, Operant; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D008691:Methadone / Q000008:administration & dosage*; D009020:Morphine / Q000008:administration & dosage; D009021:Morphine Dependence; D051381:Rats
D009020:Morphine; D008691:Methadone