[What is the consensus on the minipill as a new contraceptive method?] Que faut-il penser de la minipill en tant que nouvelle methode contraceptive.
The efficacy, side effects, and biologic actions of the progestogen-only minipills marketed since February 1973 are reviewed. The preparations are: 350 mcg norethisterone (Micronor Ortho), 30 mcg d-norgestrel (Microlut Schering and Microval Wyeth), and 500 mcg lynestrenol (Exluton Organon). The efficacy of these drugs depends on motivation: Pearl indexes vary from 1.17-3.72 for norethisterone, .9-4.4 for d-norgestrel, and .8- 2.2 for lynestrenol. Some physiologic effects of minipills possibly related to their mode of action are impermeable cervical mucus and low levels of progesterone, pregnanediol, estrogen, and LH. The side effects influencing dropout most are spotting (40-55% in the first cycle), polymenorrhea (about 10%), and amenorrhea (about 5-10%). Some transient estrogenic side effects such as nausea, headaches, and breast pain may be due to estrogenic metabolites from lynestrenol and norethisterone. None of the severe estrogenic side effects, such as thrombophlebitis and impaired glucose tolerance and liver function, are characteristic of progestogen pills.