DEVELOPMENT OF MORPHINE GLUCURONIDATION IN PREMATURE NEONATES

In premature neonates (25-34 weeks gestation) who were given morphine intravenously during the first 24 h of life, only morphine, and morphi ne-3-glucuronide (M3G) were detected in plasma obtained after a 2-hour loading infusion, but morphine-6-glucuronide (M6G) could also be quan tified following 24 h of continuous infusion. M3G/morphine and M6G/mor phine plasma concentration ratios increased significantly with increas ing birth weight. However, the M6G/M3G plasma concentration ratio decr eased with increasing birth weight (and gestational age), thus providi ng the first indication in vivo of the differential development of uri dinediphosphate glucuronosyltransferases in humans.