Pharmacodynamics of combined estrogen-progestin oral contraceptives: 1. Effects on metabolism

Introduction: The risk-benefit profile of any pharmacologic agent must be evaluated against risks connected with the events to be avoided. This is especially true in the case of hormonal contraception, not intended to combat a disease. Over the six decades during which their use has progressively expanded, the risk-benefit profile of combined oral contraceptives (COC) has substantially changed, with new combinations, dosages and mode of administration appearing on the market. Area covered: In a series of articles, recent information on the complex issue of COC risks and benefits will be reviewed in the hope of providing an updated picture. The present article reviews metabolic changes occurring during use of modern combinations of estrogens (ethinyl estradiol, estradiol, estradiol valerate and estetrol) and new progestins (desogestrel, gestodene, dienogest, drospirenone, nomegestrol acetate), often compared to classic compounds, such as levonorgestrel. Three categories of metabolic effects in healthy women are detailed: on carbohydrates, lipid and bone mineral content. Expert commentary: Overall, the picture is reassuring: the new generations of progestins are basically devoid of androgenic, estrogenic or glucocorticoid related side-effects. This should result in an improved safety profile, although past history teaches us that that large comparative and surveillance studies are required before firm conclusions can be drawn. At any rate, available evidence indicates that metabolic effects of third and fourth generation progestins, especially when they are combined with natural estrogens, are minimal and, if used in healthy women, should not cause concern.