Metabolic interaction between morphine and naloxone in human liver. A common pathway of glucuronidation?

Metabolic interaction between naloxone and morphine has been studied in vitro in human liver microsomes. Morphine and naloxone are metabolized by an UDP-glucuronyl transferase to their 3-glucuronides. There is a very good correlation between the rates of formation of morphine-3-glucuronide and of naloxone-3-glucuronide. Naloxone seems to have a 10-fold higher affinity for the enzyme binding site than does morphine. Morphine and naloxone show bisubstrate kinetic patterns which appear very similar.