3Beta-hydroxy-20-oxo-pregn-5-ene-16 alpha-carbonitrile, a potent catatoxic steroid devoid of an abortifacient effect.

PCN (3beta-Hydroxy-20-oxo-pregn-5-ene-16alpha-carbonitrile), a potent catatoxic steroid devoid of all other classic hormonal properties, given in doses amply sufficient to induce hepatic drug-metabolizing enzymes and inhibit the anesthesia caused by massive amounts of progesterone in pregnant rats, did not modify: 1. the pregnant:mated ratio, 2. the length of gestation, 3. the number of implantation sites, and 4. the size of the litter. The viability and postpartum development of the offspring were normal, as judged by gross macroscopic examination. PCN had no adverse effects on pregnancy after hypophysectomy (day 12), or ovariectomy (day 8) in rats treated with maintenance doses of progesterone and estrone. It would therefore appear that the pregnancy-maintaining capacity of endogenous or exogenous steroids (administered as substitution therapy following the glandular extirpations) was not altered by PCN and that hypothalamo-hypophyseal regulatory mechanisms were not responsible for the failure of the steroid to provoke abortion. As judged by our in vivo experiment, this pure hepatic microsomal exzyme inducer does not modify the steady state of steroid-dependent physiologic functions.