A 12-month comparative investigation of reliability, cycle control and tolerance with low-dose oral contraceptives containing 20 mu g ethinylestradiol and either 75 mu g gestodene or 150 mu g desogestrel

The clinical profile of an oral contraceptive is influenced not only by the estrogen dose, but also by the progestogen present in the preparation. Progestogens are not all equal, especially with respect to cycle control, and therefore it can be of value to compare preparations with the same estrogen dose but different progestogens. In this study, contraceptive reliability, cycle control and tolerance of an oral contraceptive containing 20 mu g ethinylestradiol and 75 mu g gestodene were compared with a reference preparation containing the same dose of estrogen combined with 150 mu g desogestrel. Interim data from 218 women/2495 cycles in the gestodene group and 219 women/2496 cycles in the desogestrel group have been analyzed from a multicenter study which is in progress in six European countries. Contraceptive reliability was found to be good with both preparations. One pregnancy occurred in the gestodene group due to intake error and additionally there was one non-study-related pregnancy which occurred after a volunteer stopped taking the pill. In the desogestrel group there were two pregnancies, one due to intake error and the other due to method failure. With respect to cycle control, there appeared to be a trend towards a lower incidence of intermenstrual bleeding in the gestodene group, although this difference did not achieve statistical significance. The cumulative incidence of spotting during the important first three cycles was 3.5% lower in the gestodene group, and, over the first six cycles, it was 7.6% lower than in the desogestrel group. It was noted that the incidence of dysmenorrhea developing during treatment was less (5.5%) in the gestodene group than in the desogestrel group (15.5%). This statistically insignificant finding needs further evaluation. Body weight remained relatively constant in both groups, as did blood pressure, with no hypertension being reported for any woman during the course of the study. The incidence of nuisance adverse events was similar in the two groups, with headache, breast tension and nausea the most frequently reported symptoms. In each treatment group, 19 women discontinued because of adverse events. It is concluded that both preparations are reliable and well-tolerated oral contraceptives. There is, however, evidence of a trend towards better cycle control in the gestodene group.