[Individualization of low-dose oral contraceptives. Pharmacological principles and practical indications for oral contraceptives].Minerva Ginecol 2007; 59(4):415-25MG
The contraceptive pill has been a revolution of the last 40 years. In Italy, however, it is much less widely used than in other countries. Explanations for this phenomenon range from religious implications and customs to misinformation and word-of-mouth communication of negative experiences. The oral contraceptive pill is often used to correct menstrual disorders, leading to poor results and side-effects. Recent advances in oral contraception have led to a substantial reduction in doses and side-effects. Low-dose pills contain minimal doses of progesterones and estrogens and ensure good control of the menstrual cycle. Although reduction of ethinyl estradiol (EE) concentrations has reduced the incidence of negative systemic side effects such as water retention, edema and swollen breasts, the low estrogen dose may be associated with spotting and hypomenorrhea or amenorrhea in the long term, as well as dyspareunia due to reduced vaginal trophism, which may induce women to suspend use of the drug. It is also true that only one type of estrogen is used in the pill, albeit at different doses, whereas the progesterone may differ and in many cases is the cause of common side-effects. The choice of progesterone therefore involves not only its effect on the endometrium in synergy with estrogen, but also possible residual androgenic activity which may have negative metabolic repercussions. Indeed, addition of a progesterone, especially androgen-derived, attenuates the positive metabolic effects of estrogen. Two new monophasic oral contraceptives were recently released. They contain 30 microg (Yasmin) or 20 muicrog (Yasminelle) EE and a new progesterone, drospirenone, derived from spirolactone, which has antiandrogenic and antimineralcorticoid activity similar to endogenous progesterone. Like progesterone, the drospirenone molecule is an aldosterone antagonist and has a natriuretic effect that opposes the sodium retention effect of EE. It may, therefore, help to prevent the water retention, weight gain and arterial hypertension often associated with oral contraceptive use. Recent comparative studies recorded weight loss that stabilized after 6 months of treatment with drospirenone/EE. Overweight women may therefore benefit from the formulation with 20 microg EE, whereas the formulation with at least 30 microg EE should be more appropriate for underweight women. Women with slight to moderate acne, the formulation with 30 microg EE has been found to be as effective as 2 mg cyproterone acetate combined with 35 micrig EE (Diane). Menstrual cycle characteristics, however, remain the main factor determining the choice of formulation. Randomised control studies comparing the new formulation with others containing second or third generation progesterones have found similar efficacy in cycle control and incidence of spotting. From this point of view, it is not advisable to prescribe more than 30 microg EE (Yasmin or Yasminelle) for women with normal menstrual cycles, whereas in cases of hypomenorrhea and/or amenorrhea at least this dose of EE plus drospirenone may be used. Women with hypermenorrhea run the risk of spotting if an inappropriate drug is chosen. A solution is to use 30 microg EE/drospirenone from day 5 of the cycle. To control so-called minor side-effects, the dose of EE must be appropriate. In women with premenstrual tension a dose of at least 30 microg EE associated with drospirenone reduces or even prevents symptoms. On the other hand, in cases of chronic headache or headache as a side-effect of oral contraceptive use, a lower dose of estrogen is beneficial, and doses below 20 microg may be used. Although the progesterone component is not considered to affect headache, good results have been obtained with drospirenone, the antimineralcorticoid effects of which reduce blood pressure and improve symptoms. Formulations with 20 microg EE and drospirenone are particularly indicated in women with pre-existing mastodynia, fibrocystic breast manifestations or who develop mastodynia as a side-effect of oral contraceptive use. Since high plasma concentrations of androgens have been recorded in these women, a progesterone with antiandrogen and antiedema activity can be beneficial. Finally, it is worth recalling that monophasic pills with low estrogen doses, such as the formulations mentioned above, ensure good mood control, reducing the depressive symptoms often associated with oral contraceptive use. In conclusion, formulations containing drospirenone are a valid alternative to conventional oral contraceptives for the personalisation of these drugs.