The metabolic fate of the anti-androgenic agent, oxendolone, in man.
After intramuscular administration of 16 beta-ethyl-17 beta-hydroxy-4-4-[4-14C]estren-3-one (14C-oxendolone; 300 mg) to 3 human subjects, excretion of 14C was very slow and incomplete despite a 20-day sample collection period. During this time, means of 37% and 21% of the administered 14C were recovered in urine and faeces, respectively, and if excretion continued at the same rate, approximately 90% of the administered 14C would have been excreted during 5-12 weeks. Peak plasma 14C concentrations were reached at 3-6 days after dosing, when they represented 0.2-1.1 micrograms equiv./ml, and declined very slowly thereafter with a half-life of 5.0-6.6 days. Concentrations of unconjugated drug-related steroids circulating in plasma never exceeded about 0.1 microgram/ml. Mass spectroscopic analysis of isolated urinary and faecal metabolites indicated that the principal routes of biotransformation of oxendolone in man are similar to those of the endogenous androgens-namely, reduction of the 4,5-double bond, further reduction of the saturated 3-ketone to the 3 alpha-hydroxysteroid, and oxidation of the 17 beta-alcohol to the corresponding ketone, followed by conjugation, mainly with glucuronic acid, and excretion in the urine and bile.
D000328:Adult; D000728:Androgens / Q000097:blood; D001711:Biotransformation; D002250:Carbon Radioisotopes; D002855:Chromatography, Thin Layer; D004958:Estradiol / Q000097:blood; D005243:Feces / Q000032:analysis; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007273:Injections, Intramuscular; D007700:Kinetics; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009277:Nandrolone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism
D000728:Androgens; D002250:Carbon Radioisotopes; D004958:Estradiol; D009277:Nandrolone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C005671:oxendolone