Morphine-3-β-d-glucuronide and morphine-6-β-d-glucuronide are the major metabolites of morphine in humans. More recently, morphine-3-β-d-glucoside (M-3-glucoside) was identified in the urine of patients treated with morphine. Kinetic and inhibition studies using human liver microsomes and recombinant UDP-glucuronosyltransferases as the enzyme sources were used here to characterize the relationship between morphine glucuronidation and glucosidation. The data indicate that morphine glucuronidation and glucosidation occur as complementary metabolic pathways catalyzed by a common enzyme (UGT2B7). Glucuronidation is the dominant metabolic pathway because the binding affinity of UDP-glucuronic acid to UGT2B7 is higher than that of UDP-glucose.
See article at J Pharmacol Exp Ther 2014, 349:126–137.
- Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics