each subject underwent six studies on separate days with intravenous infusion of saline , naloxone 40 micrograms/kg/hr , morphine sulfate 40 micrograms/kg/hr , morphine and naloxone combined , naloxone and atropine 13 micrograms/kg/hr , and morphine and bethanechol 16 micrograms/kg/hr .
C0066814
morphine sulfate
C0026549
morphine