Some aspects of the metabolism of morphine-N-oxide

Abstract

Abstract After administration of morphine-N-oxide (MNO) to rats the opiates appearing in the urine were morphine (61%) and MNO (39%). After administration of morphine, the urinary opiates were morphine (80%) and normorphine (20%). When tacrine was given with morphine the urine also contained MNO (46% of total urinary opiates) and the amount of normorphine was much decreased (to 1%), the remainder being morphine (53%). Tacrine and amiphenazole inhibited demethylation of morphine and codeine by a rat liver fraction in vitro. MNO had weak inhibitory activity. Neither MNO nor codeine-N-oxide were demethylated in vitro.