Species difference in codeine uridine diphosphate-glucuronyltransferase activity of liver microsomes

Species difference in codeine uridine diphosphate-glucuronyltransferase (UDPGT) activity was studied in liver microsomes of mice, rats, guinea pigs and rabbits. Codeine UDPGT activity was the highest in guinea pigs, followed by that in rabbits, and the lowest in mice and rats among these four animal species. The specific activities of codeine UDPGT in liver microsomes were not correlated well with those toward morphine, 4-nitrophenol, and 4-hydroxybiphenyl in liver microsomes of each of the species. Inducibility of liver microsomal codeine UDPGT activity in rats was examined by pretreatment with phenobarbital and 3-methylcholanthrene and compared with those of other UDPGT activities. The activity was inducible by phenobarbital pretreatment as the activity toward morphine and 4-hydroxybiphenyl. The inducibility of codeine UDPGT activity by phenobarbital pretreatment was not as high as that of morphine UDPGT activity.