Different cardiovascular effects of progestins according to structure and activity

Following the publication of the Women's Health Initiative study, the controversy was raised regarding the role of progestins in hormonal replacement therapy (HRT). Some of the most prescribed molecules, with partial androgenic or glucocorticoid activity, have been shown to oppose partially the beneficial effect of estrogens on surrogate markers of cardiovascular disease risk. Unfortunately, this concern has been directed towards progestins as a class effect, although striking differences exist among the types of molecules used. The synthetic progestins used in HRT have varying pharmacologic properties depending on the molecules from which they are derived, either testosterone or progesterone. Very small structural changes in these molecules may induce considerable difference in their effects on various targets and especially on the surrogate markers of cardiovascular disease risk, where some molecules may reverse the beneficial effects of estrogen. Natural progesterone and some of its derivatives such as the 19-norprogesterone molecules or the new molecules drospirenone, a potent antimineralocorticoid agent with a beneficial effect on blood pressure, and dienogest do not exert any androgenic effect and have no negative effect on the lipids or on the endothelial cells. Although it is likely that the new progestins may be neutral on the coronary disease risk, when administered to the younger postmenopausal woman, this has not as yet been documented by large, randomized, controlled trials.