PT  - JOURNAL ARTICLE
AU  - EDWARD J. CONE
AU  - CHARLES W. GORODETZKY
AU  - S. Y. YEH
TI  - THE URINARY EXCRETION PROFILE OF NALTREXONE AND METABOLITES IN MAN
DP  - 1974 Nov 01
TA  - Drug Metabolism and Disposition
PG  - 506--512
VI  - 2
IP  - 6
4099  - http://dmd.aspetjournals.org/content/2/6/506.short
4100  - http://dmd.aspetjournals.org/content/2/6/506.full
SO  - Drug Metab Dispos1974 Nov 01; 2
AB  - The urinary excretion pattern of free and conjugated naltrexone and the metabolite 6-β-hydroxynaltrexone was determined for six human subjects for a period of 6 days after oral administration of 50 mg of naltrexone. The levels of free and conjugated drug and metabolite were determined by a gas-chromatographic analysis procedure using naloxone as an internal standard and by correlating peak height ratios to concentration. The mean excretions ± SE of free naltrexone and 6-β-hydroxynaltrexone were estimated as 1.2 ± 0.2 and 26.3 ± 2.2% of administered dose, respectively. The mean excretions of conjugated naltrexone and metabolite were estimated as 9.7 and 16.4% of administered dose, respectively. The timed urinary excretion profile indicated that naltrexone is metabolized and excreted rapidly (mean excretion t½ = 1.1 hr), whereas the free metabolite, 6-β-hydroxynaltrexone, persists at detectable levels for 6 days (mean excretion t½= 14-18 hr). Preliminary dose-ranging studies of 6-β-hydroxynaltrexone in the chronic spinal dog suggest antagonistic activity of the metabolite. Copyright © 1974 by The American Society for Pharmacology and Experimental Therapeutics