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R. B. GREENBLATT The original oral contraceptives contained more oestrogen in the form of ethinyloestradiol or mestranol and progestagen in the form of norethynodrel or norethisterone than was necessary f(x conception control. There has been a trend over the years to reduce dosages of both components in order to minimize side eHects while ensuring eflcctiveness. However, as dosages were lowered, there has been an increase in spotting and break through bleeding during the first few months of their adminis tration. The sequential pill appeared more physiological in that it followed more closely physiological principles, but the need to employ large doses ofEE or EE3ME to inhibit O ’ulation and the higher pregnancy rate made the sequential regimen less attrac ti ’e or useful. A triphasic formulation has become available that takes advantage of the synergism between ethinyloestradiol and the potent levonorgestrel so that low doses of the oestrogen and very low doses of the progestagen could be employed with great effectiveness. Such a preparation is relatively free from side effects, partly because the basic pharmacological tenet of the minimal dose for the desired result and the division of’the cycle into three parts using 30 ,lIg ofEE for the first 6 days, then:) days of 40 ,lIg, followed by 30 ,fIg for 10 da ys, for a total of21 days, thus more or less mimicking the physiological rise and fall of 125 THE DEVELOP:’IE:-;T OF , :-;E ’ TRIPH. SIC OR.
