%0 Journal Article %A L A Raitano %A W Slikker, Jr %A D E Hill %A H E Hadd %A T Cairns %A E D Helton %T Ethynyl cleavage of 17 alpha-ethynylestradiol in the rhesus monkey. %D 1981 %J Drug Metabolism and Disposition %P 129-134 %V 9 %N 2 %X 17 alpha-Ethynylestradiol (EE2)[20,21-14C] and [9,11-3H] were administered by intragastric intubation to three adult female rhesus monkeys. Quantification of the tritium isotope indicated that the peak plasma radioactivity (3.4-6.8% of dose) occurred between 30 and 60 min, whereas 36-39% of the administered tritium appeared in the urine in the first 96 hr. Fecal excretion was 9.17.0% during the same period. Fractionation and isolation of the urinary conjugates were accomplished by chromatography on Sephadex LH-20 followed by HPLC. Cochromatography of radioactive fractions with authentic steroid glucuronide standards gave presumptive evidence for the presence of ethynylestradiol and estrone glucuronides. Following hydrolysis, the tritium-labeled natural estrogens, estrone and estradiol-17 beta, were identified with reverse-isotope recrystallization, demonstrating that the de-ethynylation of EE2 had occurred. %U https://dmd.aspetjournals.org/content/dmd/9/2/129.full.pdf