Sequential therapy to achieve anovulatory cycles.

Sequential oral contraceptive therapy was devised to inhibit ovulation by a potent estrogen alone. A progestational agent was added at the end of the course of therapy to prepare the endometrium for adequate withdrawal bleeding. The program consisted of giving 80 mug. of metranol daily for 15 days and then a combination of 80 mug. of mestranol and 2 mg. of chlormadinone acetate for five additional days. Such a regimen proved to be effective in 6070 patients carefully observed for 82,085 cycles of therapy at 25 medical centres.INCREASED CYCLE REGULARITY WAS NOTED: 98.1% of the cycles were 25 to 31 days long. In 80.1% of cycles, the withdrawal interval was two to five days in length. Duration of flow was four to six days in 85.3% of the therapeutic cycles. The amount of flow decreased as compared with pretreatment values. The incidence and severity of dysmenorrhea during sequential therapy were significantly lower than before treatment. Side effects, usually infrequent, diminished as therapy was continued; the average incidence of breakthrough bleeding was 1.9% and nausea was 2.9%. Extensive laboratory studies showed no consistent abnormalities. For oral contraception, sequential therapy has proved to be virtually 100% effective when taken as directed.