Molecular biology and oral contraception.

Recent developments in knowledge of sex hormone receptors and steroid analogue metabolism allow a rational selection of oral contraceptive steroids from among the numerous available products. Dose related metabolic effects of synthetic estrogens have been demonstrated. Many of these estrogenic actions are antagonised by norgestrel but not by any other commercially available progestogen. Generalised activation of lysosomal enzymes can be demonstrated in oral contraceptive users and is shown to be related to the total steroid dose per cycle, rather than to particular products. These findings suggest that the lowest dose combination of ethynylestradiol and d-norgestrel is the product of choice. Clinical results with such a product are described.