How progestins influence the cardiovascular effect of hormone replacement therapy

Effect of hormone replacement therapy with the anti-mineralocorticoid progestin Drospirenone compared to tibolone on endothelial function and central haemodynamics in post-menopausal women

Drospirenone (DRSP) is an antialdosterone agent with progestogenic and antiandrogenic effects. This compound, has been recently used in combination with 17β-estradiol (E2) as hormonal therapy in postmenopausal women and has been shown to exert a significant antihypertensive effect in hypertensive post-menopausal women. Aim of the present study was to compare the effect of DRSP/E2 with those of Tibolone (T) on endothelial function, arterial stiffness, and lipid profile of early postmenopausal women naïve on post-menopausal hormonal therapy. Twenty-four women met the inclusion criteria and entered the study. Women were randomized to receive either DRSP/E2 or T for 6months. Blood pressure and heart rate were similar in both groups at baseline and at the end of the study. Compared to baseline, endothelial function assessed by Reactive Hyperemia (RH) significantly improved in women receiving E2/DRSP, whereas no significant differences between baseline and follow up were detected in women receiving Tibolone. Women receiving E2/DRSP showed a significant decrease in pulse wave velocity and Augmentation Index compared to baseline while no changes were observed in women receiving Tibolone. The capacity of sera to trigger endothelial cells apoptosis in vitro measured by cell death assay was significantly reduced by E/DRSP but not by T (HFA-E 70±5,6% vs HFD-E 41±4,5%, p<0,001). In conclusion, the present study shows that the association of Estradiol and Drospirenone as hormonal replacement therapy significantly improves vascular parameters and the composition of sera relevant for vascular protection in early post-menopausal normotensive women. These effects are not shared by Tibolone.

Molecular mechanisms of steroid receptor-mediated actions by synthetic progestins used in HRT and contraception

Synthetic progestins are used by millions of women as contraceptives and in hormone replacement therapy (HRT), although their molecular mechanisms of action are not well understood. The importance of investigating these mechanisms, as compared to those of progesterone, has been highlighted by clinical evidence showing that medroxyprogesterone acetate (MPA), a first generation progestin, increases the risk of breast cancer and coronary heart disease in HRT users. A diverse range of later generation progestins with varying structures and pharmacological properties is available for therapeutic use and it is becoming clear that different progestins elicit beneficial and adverse effects to different extents. These differences in biological activity are likely to be due to many factors including variations in dose, metabolism, pharmacokinetics, bioavailability, and regulation of, and/or binding, to serum-binding proteins and steroidogenic enzymes. Since the intracellular effects on gene expression and cell signaling of steroids are mediated via intracellular steroid receptors, differential actions via the progesterone and other steroid receptors and their isoforms, are likely to be the major cause of differential intracellular actions of progestins. Since many progestins bind not only to the progesterone receptor, but also to the glucocorticoid, androgen, mineralocorticoid, and possibly the estrogen receptors, it is plausible that synthetic progestins exert therapeutic actions as well as side-effects via some of these receptors. Here we review the molecular mechanisms of intracellular actions of old (MPA, norethisterone, levonorgestrel, gestodene) vs. new (drospirenone, dienogest, trimegestone) generation progestins, via steroid receptors.

Effects of estradiol alone and combined with norethisterone acetate on pulse-wave velocity in hypertensive postmenopausal women

BACKGROUND

Arterial hypertension and postmenopausal reduction of estrogen levels may be involved in modifications of the stiffness of large arteries.

OBJECTIVES

To evaluate the pulse-wave velocity (PWV) and indirectly the arterial stiffness in hypertensive postmenopausal women submitted to hormone therapy with estradiol alone or combined with norethisterone acetate.

SUBJECTS

Forty-five hypertensive postmenopausal women were double-blindly, randomly assigned to three arms of treatment: placebo (group I); estradiol 2 mg/day (group II); or estradiol 2 mg/day and norethisterone acetate 1 mg/day (group III).

METHODS

Arterial stiffness was assessed from PWV measurements of the common carotid and femoral arteries (CF-PWV) and the common carotid and radial arteries (CR-PWV) obtained using the automatic Complior(R) device, taken at baseline and after 12 weeks of treatment.

RESULTS

After the 12-week treatment, values of CF-PWV and CR-PWV were not significantly different (p = 0.910 and p = 0.736, respectively) among the groups. Systolic blood pressure showed a positive correlation with CF-PWV in groups II and III (p = 0.02 and p < 0.001, respectively).

CONCLUSIONS

PWV and arterial stiffness in postmenopausal hypertensive women did not reduce over a 12-week treatment with estradiol alone compared with the same period of treatment with estradiol combined with norethisterone acetate.

Metabolic and vascular effect of progestins in post-menopausal women. Implications for cardioprotection

Estrogen therapy causes changes in a variety of cardiovascular risk factors, including insulin resistance, lipoprotein profile, haemostasis, coronary atherosclerosis and vascular reactive, that suggest a potential cardioprotective effect in postmenopausal women. With respect to the role of adjunctive progestins, currently available data suggest that the cardiovascular effects may differ depending on the type, dosage and route of administration of the progestin. Androgenic progestins antagonise the favourable cardiovascular effect of estrogens, whilst non-androgenic progestins do not impair, or may even enhance, the beneficial effect of estrogens. Therefore, less androgenic progestins would appear to be the agent of choice for combined hormone therapy in postmenopausal women with cardiovascular risk factors.

[Hormone therapy in menopause. A current update]

While the use of hormone replacement therapy (HRT) for prophylactic indications such as cardiovascular disease, osteoporosis, and Alzheimer's disease was increasingly propagated during the 1990s, recent studies have reported no risk reduction for women after myocardial infarction (HERS) or women from a mixed population with an average age of 63 years (Women's Health Initiative [WHI] Study). The results of the latter study even suggest an increased risk for cardiovascular events and breast cancer with previous or ongoing combined oral estrogen plus progestin. A final risk-benefit assessment for estrogen monotherapy will only be possible after the ongoing part of the WHI Study has been evaluated, expected in 2005. As effects, side effects, and contraindications for HRT in postmenopausal women are better known, the need for individualized risk assessment and the definition of therapeutic goals increases. Since the WHI Study did not address the risk-benefit ratio for women with perimenopausal complaints or osteoporosis or with lower dose hormone preparations commonly used in Germany, there is an urgent need to answer these open questions with large confirmative studies.