[Postcoital contraception in primates. II. Examination of STS 153 and STS 287 as interceptives in the baboon (Papio hamadryas)].

The interceptive activity of 2 new synthesized steroid compounds: STS 153 (17 beta-Phenylaminocarbonyloxy-estra-1,3,5(10)-triene-3-methyl ether and STS 287 (16 alpha-Bromo-17 beta-[N',N'-dimethylhydrazino]-carbonyloxy-estra-1,3,5(10)-triene-3-methyl ether) and of 17 alpha-Ethynylestradiol was investigated in baboons.--Postcoital oral administration of 1--3 mg/kg b. w. STS 153 for 5--7 days and of 1 mg/kg b. w. STS 287 for 5 days resulted in a fertility inhibition of about 90% and 95% respectively. A dose of 2 mg/kg b. w. of ethynylestradiol was necessary to attain complete fertility inhibition. Following administration of STS 153 and STS 287, side effects were not observed. Pharmacokinetic aspects are discussed.