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  • Title: Clinical use of biphasic and triphasic pills.
    Author: Cohen J.
    Journal: IPPF Med Bull; 1985 Aug; 19(4):1-2. PubMed ID: 12280230.
    Abstract:
    In the last 25 years, considerations about the use of steroids in oral contraceptives (OCs) have undergone considerable changes for 3 main reasons: the need to reduce the overall doses of steroids in order to avoid cardiovascular accidents and longterm metabolic problems; the development of new steroids; and the impossibility of reducing the daily amount of ethinylestradiol given alone without reducing the effectiveness of the OC -- a fact which led to the abandonment of sequential pills in favor of combined OCs. These allow for the use of a minimum dose of estrogen in constant combination with a progestagen. Yet, very low dose combined OCs fail to give complete control over the menstrual cycle. They also cause side effects because of an unsatisfactory estrogen-progestagen balance. Bleeding early in the cycle is caused by a relative insufficiency of estrogen and late bleeding by a relative insufficiency of progestagen. It is for these reasons and to produce cycles more closely resembling the natural ones that biphasic and later tripasic OCs were developed. Biphasic pills provide in succession 2 estrogen-progestagen combinations in increasing doses. Triphasic pills provide a continuous dose of estrogen combined with a progressively increased dose of progestagen from week to week. In general, the biphasic and triphasic pills conform to the criteria of an ideal OC: inhibition of ovulation, moderate blocking of the pituitary, satisfactory proliferation of the endometrium, and changes in the cervical mucus. In respect of these factors, there have been no changes. What is new with biphasic pills is that the increase in the steroid doses over the cycle reduces the incidence of spotting and bleeding and the incidence of amenorrhea associated with the use of low-dose monophasic combined OCs. The triphasic formulation improves this concept still further: the increased dose taken in the middle of the cycle allows for the possible peaks of luteinizing hormone which are blocked. This formulation allows the use, at the very beginning of the pill cycle, of very low doses, which will then be slightly increased in the 2nd and 3rd weeks. The reduction in the overall doses of steroids in each cycle is a desired objective. The effectiveness of the biphasic pills is excellent, with a Pearl Index of 0.0-1.0/100 woman years, depending on the formulation. Formulation G of the triphasic OCs has a Pearl Index of less than 0.22/100 woman years. Various studies of biphasic OCs show that a reduction of the dose of estrogen from 50 mcg to 30 mcg brings a reduction in the abnormalities of hemostasis and hypertriglyceridemia and a reduction of the diabetogenic effects. There are some metabolic problems. The rate of amenorrhea is remarkably low. The medical supervision required and the contraindications to these biphasic and triphasic formulations are similar to those which apply to all OCs. It is concluded that the phasic OCs are the best choice in OCs today.
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