| Abstract: | An orally active progestagen, 17 alpha-ethynyl-19-nor-testosterone-17 beta-acetate-3-cyclopeotyl enol-ether (ENTACP) was found to be a potent antiestrual and contraceptive agent in rats. It was evaluated with respect to: 1) progestational activity, 2) pregnancy maintenance, 3) androgenic activity, 4) masculinization of female fetuses, 5) uterotropic activity, 6) effect on adrenal and adrenocortical function, 7) effect on organs and body weight, 8) effect on pregnancy, 9) storage in body fat. ENTACP was twice as effective in producing secretory changes of the endometrium as its parent compound. Pregnancy was not maintained; however, after 22 days, resorption sites were still visable. ENTACP was about 1.5 times as effective as its parent compound in stimulating accessory organs during daily administration. A daily dose of .9 mg orally produced masculinization of the female fetuses, but did not interfere with parturition. Resorption of fetuses occurred more frequently in rats treated with ENTACP than with other compounds tested. ENTACP behaved like an estrogen in stimulating uterine growth. Adrenal weight was significantly increased with ENTACP administration and it reduced the capacity of the adrenal cortical tissue to respond to ACTH. Body weight gain suffered in direct proportion to dose administration. Adrenals, hypophysis, and thyroid increased when expressed in mg/100 gm body weight, and thymus decreased. The oral daily dose of .5 mg/animal from day 1-11 after mating did not prevent pregnancy. At the 5 mg/animal dose nidation was interfered with. Oral administration was not followed by storage of steroid material in body fat. |
