Naltrexone metabolism and sustained release following administration of an insoluble complex to rhesus monkeys and guinea-pigs.
Both the release and the metabolism of naltrexone have been evaluated after intramuscular administration of a sustained release [15,16-3H2]naltrexone aluminium tannate complex in guinea-pigs and rhesus monkeys. In both species, measurable excretion of radioactivity was obtained for greater than 50 days and complete recovery of the dose was obtained in the guinea-pig. The radioactivity excretion rate-time profile differed in the two species with guinea-pig yielding a continuously declining rate and monkey yielding a peak at 5 days. In selected monkey urine samples (days 4, 17-20 and 49-52) subjected to t.l.c., evidence was obtained for the presence of naltrexone, beta-naltrexol and 2-hydroxy-3-O-methyl-beta-naltrexol, mostly as glucuronide and/or sulphate conjugates. The t.l.c. data also suggest that in monkey a naltrexone metabolite builds up relative to naltrexone over the 52 day release period.
D000818:Animals; D001711:Biotransformation; D002855:Chromatography, Thin Layer; D003692:Delayed-Action Preparations; D005260:Female; D006168:Guinea Pigs; D006868:Hydrolysis; D008253:Macaca mulatta; D008297:Male; D009270:Naloxone / Q000031:analogs & derivatives*; D009271:Naltrexone / Q000008:administration & dosage / Q000378:metabolism*; D013045:Species Specificity; D013997:Time Factors
D003692:Delayed-Action Preparations; D009270:Naloxone; D009271:Naltrexone