Triphasics: have they fulfilled their promise?
Weisberg, E.
Current Therapeutics 33(1): 11-16
1992
ISSN/ISBN: 0311-905X PMID: 12286973 Document Number: 329481
Triphasic oral contraceptives (OCs) were designed to use the least amount of drugs for the desired effect and to imitate the physiology of the menstrual cycle, resulting in good cycle control and minimal side effects. Yet, studies indicate that triphasic OCs cause only marginally better cycle control than monophasic OCs with reduced frequency of withdrawal bleeding. In fact, the triphasic OCs in Australia do not mimic the normal menstrual cycle. Theoretically, the lowered total steroid doses more gently inhibits the hypothalamic-pituitary function via the absence of a midcycle surge of estradiol and luteinizing hormone and the absence of a rise in luteal progesterone, allowing a more rapid return to functional fertility. 2 triphasic OCs contain the progestogen norethisterone, and the other one contains levonorgestrel. Triphasic OCs appear to have a somewhat lower effect on lipid and carbohydrate metabolism than do current monophasic OCs. Clinicians have not conducted longterm prospective studies on triphasic OCs, so no evidence exists to support the contention that they are less likely to have cardiovascular effects than monophasic OCs. Further, triphasic and monophasic OCs have basically the same effect on blood coagulation factors. OCs have basically the same effect on blood coagulation factors. Many large-scale clinical trials show that the pregnancy rate is around .06. The low dose of levonorgestrel in the beginning of the cycle may reduce effectiveness, however, if women make mistakes. Further, the more complicated packaging of triphasic OCs may make it easier for women to make a mistake. Triphasic OCs may reduce the severity of acne. Most women find triphasic OCs to be quite acceptable, but, in a small group of women, its phasic formulation causes some side effects, including premenstrual syndrome, breast tenderness, excessive bleeding, or painful menstruation.