Abstract

PIP: The main advantage of the triphasic oral contraceptive (OC) is its reduced corticosteroid content, which is accompanied by a reduction in metabolic impact. Triphasic pills differ according to their components and according to whether or not their estrogen dose is constant. The Triella pill has a constant dose of 35 mcg ethinyl estradiol (EE) and a dose of norethisterone that increases from .50 to 1 mg, while Triquilar-Trinordiol mimics the preovulatory estrogen peak while also varying the progestin content. In a study of 22,728 cycles, the Pearl index was only .06/100 woman years for triphasic pills. Comparisons with existing monophasic pills indicate that triphasics may offer improved cycle control, but the fact should be emphasized to patients that cycle control is an inappropriate criterion for choice of pills. Metabolic effects or possible carcinogenic effects are more important qualities. Triphasic pills have been found to improve acne, not to affect weight or blood pressure, and to reduce the frequency of headaches, nervousness, and breast tenderness. Studies have shown that triphasics containing levonorgestrel produce minimal effects on lipid metabolism, while less rigorous studies on triphasics containing norethisterone have also yielded favorable results. It is true however that knowledge of the relationship between alterations in plasma cholesterol caused by Triella use and the etiology of certain diseases remains incomplete. Low dose triphasic pills appear to have fewer deleterious effects on glucose metabolism than higher dose pills, but they are not entirely without effect and should not be prescribed for women at risk of developing diabetes. Studies examining modifications of the intima and coagulation factors have given reassuring results, and neither triphasics with levonorgestrel nor those with norethisterone modify the blood pressure. Triphasics entail a reduction in the levels of estradiol and testosterone and a slight increase of plasma renin activity but no modification in plasma aldosterone. The subtle effects on the gonodotropic axis are considered especially fitting for young women in whom post-pill ovulatory function is preserved. Endometrial biopsies show that the state of the endometrium with OC use is not well understood and highly variable. The triphasic pill approaches as closely as possible the normal physiology of the endometrium while still suppressing ovulation.