Contraceptive efficacy of 200μg R2323 and 10μg R2858
Investigation into the contraceptive efficacy of 200 μg R2323 (13-ethyl-17-hydroxy-18, 19-dinor-17α-pregna-4, 9, 11-trien-20-yn-3-one) and 10 μg R2858 (11β-methoxy-17α-ethinyl-oestradiol) as a combination pill, was carried out in a group of 86 healthy females of proven fertility during 667 cycles (mean 7.74 cycles). A total of 10 pregnancies occurred for a pregnancy rate of 19.5, computed by the Pearl formula, but only four were considered drug failures. Although side-effects were generally minimal, one case of cerebral thrombosis was reported. Only two women complained of menorrhagia and three developed amenorrhoea while on therapy. Papanicolaou smears were taken at two- to three-month intervals for a total of 161 smears and no malignant changes were recorded.