AN ASSAY FOR ANABOLIC STEROIDS EMPLOYING METABOLIC BALANCE IN THE MONKEY: THE ANABOLIC ACTIVITY OF FLUOXYMESTERONE¹AND ITS 11-KETO ANALOGUE¹

Abstract

A procedure for conducting metabolic balance studies in the Macaca mulatta monkey was presented. A Latin square design employing four monkeys, four doses of fluoxymesterone and four drug periods, each preceded and succeeded by its own control period, produced linear response curves over the full dose range, 50-400 μg./kg./day, for nitrogen retention expressed as total N retained per day during drug periods, increased N retained during drug periods with respect to pre- and post-drug control periods and for body weight gains. Residual effects of treatment in any period on responses in the treatment period immediately following were negligible. Average estimates of increased N retained as a percentage of body weight gain compared favorably with the reported N content of mammalian muscle. A statistically balanced twin crossover assay was studied. Fluoxjnnesterone was employed as the standard and 9α-fluoro-ll-keto-17α-methyltestosterone as the test compound.Nitrogen retention, potassium retention and body weight gain demonstrated the anabolicpotency of the test compound to be equal to that of fluoxymesterone. The efficiency of the experimental design was calculated to be 1.5 to 2. It is concluded that metabolic balance procedures can be employed for quantitative bioassay of anabolic agents in the monkey and probably in other species provided proper experimental design is used.