Clinical experience with a triphasic oral contraceptive.
A triphasic combined oral contraceptive containing fluctuating amounts of ethinylestradiol and levonorgestrel was tested clinically in a multicenter trial at six hospitals in Norway. 367 women were included in the study, 3 588 cycles were studied, and the follow up period was 12 months. The one year continuation rate was 67%. Five pregnancies occurred during the study period. All of them had to be considered as patient failures. The causes for stopping medication were side effects in about 50% and the rest for personal reasons. The cycle control taking into account duration of bleeding, amount of flow, and intermenstrual bleeding was good and comparable to the low-dose monophasic combined pills. The incidence of side effects was low. One woman had an increase in systolic blood pressure to more than 140 mmHg. Thrombophlebitis was not registered. In conclusion the triphasic oral contraceptive was effective and had a good cycle control and low incidence of side effects.