[Oral contraceptives: clinical pharmacology, composition, choice of preparation].

Following introductory terminological clarifications, the pharmacological peculiarities of the synthetic estrogens and progestogens used in oral contraception are outlined. With the low-dose formulations containing less than 50 micrograms estrogen per pill ("micropill") coming in preferential use, the definite differences between the profiles of effects of the three major progestational categories--estranes, gonanes and pregnanes--lost much of their impact on clinical tolerance. Within the three classes of progestogens, the profiles of effects of the various compounds are, anyhow, very similar with major deviations occurring only exceptionally. As to the contraceptive estrogens, ethinyl estradiol differs from mestranol, if any, in quantitative but not in qualitative respect, the latter substance not being commonly used in Europe any longer. Besides potencies and profiles of effects of the individual contraceptive steroids, the quantitative estrogen/progestogen relationship of a "pill" is another variable of great importance for the development of unwanted side effects in the field of lipid and carbohydrate metabolism as well as of blood coagulation. Due to the lack of influence on lipid metabolism, progestogens of the pregnane series, being driven into an outsider position since long, deserve increasing attention again. As a general principle, women of all age groups should at least try to use the "micropill"--either combination-type or tristep formulations--in order to minimize risks. Only a few indications are left for the primary prescription of high-dose combination-type, sequential and step-up preparations as well as for the progestogen-only "minipill". With "micropill" becoming the oral contraceptives of the first choice, also rational reasons for changing formulations have become rare.(ABSTRACT TRUNCATED AT 250 WORDS)