A low-dose triphasic oral contraceptive.

Controlled clinical investigations of a three-phase, low-dose oral contraceptive combination of levonorgestrel and ethinyl estradiol were conducted at 17 sites in the United States and 60 sites in the United Kingdom. A day 1 start in cycle one with no backup contraception was used. A total of 3546 female volunteers participated in 35,036 cycles. Medication was missed in 2688 (7.7%) cycles. Nine pregnancies were reported for an uncorrected use-effectiveness rate of 0.33 per 100 woman-years. Cycle control was excellent, bleeding irregularities were minimal, and the incidence of side effects was very low. No clinically significant variations in blood pressure means or weight means were observed. Carbohydrate and lipid metabolism studies were limited to 6 months and showed minimal alterations. Subject compliance with the preparation was excellent. It is concluded that this triphasic oral contraceptive with its varying ratios of levonorgestrel and ethinyl estradiol is an effective, predictable, and well-tolerated combination oral contraceptive.