Rationale for prescribing oral contraceptives
Teichmann, A.T.
Wiener Medizinische Wochenschrift 148(7): 171-174
1998
ISSN/ISBN: 0043-5341 PMID: 9700865 Document Number: 283409
It is vital when one is prescribing oral contraceptives to choose antiestrogenic gestagens with antiandrogenic properties if conditions like acne, alopecia, or hirsutism are present. Cyproterone acetate, chlormadinoacetate, and dienogest are the most effective antiandrogens. Sex hormone-binding globulin (SHGB) is the most important parameter for the effect of estrogen on the liver, and its measurement can help determine the total estrogen content of various preparations. The SHGB increase should always be measured after at least 3 cycles of treatment with monophasic combination preparations of different gestagens. The dose of ethinyl estradiol for levonorgestrel (LNG), gestoden, desogestrel, and dienogest, respectively, used to be 30 mcg, and for norgestimate and norethindrone it was 35 mcg; the dose would be assessed to ascertain the antiestrogenic effect of these preparations. LNG is the gestagen with the strongest antiestrogenic effect. This has been qualitatively supported by findings from an investigation with a combination of 20 mcg ethinyl estradiol plus 100 mcg LNG, which showed that no change of the SHGB level occurred after 3 cycles. It is reasonable to choose a preparation with the lowest estrogen and gestagen dose and to change the dosage only after 3-4 months of use at the earliest if side effects such as bleeding irregularities occur. Other options are gestagen monopreparations or an LNG-containing IUD system. For women in the last third of their fertile phase, the use of a gestagen-containing system allows for the balancing of an existing estradiol deficit.