Administration of raloxifene does not influence 24-hour ambulatory blood pressure of postmenopausal women with osteopenia: a double-blind placebo-controlled study

Assessment of Cardiovascular Safety of Anti-Osteoporosis Drugs

The incidence of osteoporosis and cardiovascular disease increases with age, and there are potentially shared mechanistic associations between the two conditions. It is therefore highly relevant to understand the cardiovascular implications of osteoporosis medications. These are presented in this narrative review. Calcium supplementation could theoretically cause atheroma formation via calcium deposition, and in one study was found to be associated with myocardial infarction, but this has not been replicated. Vitamin D supplementation has been extensively investigated for cardiac benefit, but no consistent effect has been found. Despite findings in the early 21st century that menopausal hormone therapy was associated with coronary artery disease and venous thromboembolism (VTE), this therapy is now thought to be potentially safe (from a cardiac perspective) if started within the first 10 years of the menopause. Selective estrogen receptor modulators (SERMs) are associated with increased risk of VTE and may be related to fatal strokes (a subset of total strokes). Bisphosphonates could theoretically provide protection against atheroma. However, data from randomised trials and observational studies have neither robustly supported this nor consistently demonstrated the potential association with atrial fibrillation. Denosumab does not appear to be associated with cardiovascular disease and, although parathyroid hormone analogues are associated with palpitations and dizziness, no association with a defined cardiovascular pathology has been demonstrated. Finally, romosozumab has been shown to have a possible cardiovascular signal, and therefore post-market surveillance of this therapy will be vital.

Role of estrogen receptors in modulating aldosterone biosynthesis and blood pressure

Blood pressure is lower in premenopausal women than in age-matched men; after menopause blood pressure values and the prevalence of hypertension show opposite trends indicating that estrogens contribute to maintaining normal blood pressure values in women. In experimental studies menopause increases aldosterone levels, an effect alleviated by estrogen treatment. We have recently discovered a role of estrogen receptors (ER) in controlling aldosterone biosynthesis in the human adrenocortical zona glomerulosa, which expresses both the classical ERα and β receptors and G protein-coupled estrogen receptor (GPER). We have also identified that GPER mediates an aldosterone-induced aldosterone response. We found that 17 β-estradiol exerts a dual effect: it blunts aldosterone production via ERβ, but displays a potent aldosterone secretagogue effect via GPER activation after ERβ blockade. Thus, in premenopausal women high estrogen levels might tonically blunt aldosterone synthesis via ERβ, thereby maintaining normal blood pressure; after menopause loss of this estrogen-mediated inhibition can contribute to increasing blood pressure via GPER-mediated aldosterone release. The additional findings that GPER mediates an aldosterone-induced stimulation of aldosterone biosynthesis and that GPER predominates in aldosterone-producing adenomas strongly involves this receptor in the pathophysiology of primary aldosteronism. Our purpose here was to provide an update on estrogen receptor function in the normal adrenal cortex and its relevance for the sex differences in blood pressure in light of the newly discovered role of GPER in regulating aldosterone synthesis. The implications of the novel knowledge for the treatment of estrogen-dependent malignancies with ER modulators are also discussed.

Raloxifene: a selective estrogen-receptor modulator for postmenopausal osteoporosis - a clinical update on efficacy and safety

Selective estrogen-receptor modulators are molecules with specific estrogen-receptor binding affinity. Each selective estrogen-receptor modulator induces a unique conformation in the ligand-receptor complex, which leads to transcriptional activation and/or inhibition. Raloxifene 60 mg/day, a benzothiophene selective estrogen-receptor modulator, is approved for the prevention and treatment of postmenopausal osteoporosis. This article provides an update on new studies and further analyses of clinical trial data for raloxifene. The Multiple Outcomes of Raloxifene Evaluation (MORE) trial of women with osteoporosis has described the efficacy of raloxifene in decreasing vertebral fracture risk over 4 years. The Continuing Outcomes Relevant to Evista((R)) (CORE) trial, designed to assess the effects of raloxifene on breast cancer prevention, is a 4-year continuation of MORE. The skeletal and cardiovascular effects of raloxifene in the CORE study were similar to those observed in MORE. The relative risk of developing breast cancer was significantly decreased in women treated with raloxifene, compared with placebo, after 4 years in MORE and 8 years in the CORE trial. The incidence of uterine bleeding, endometrial hyperplasia and endometrial cancer was similar between raloxifene and placebo after 8 years of treatment. Raloxifene use is associated with a higher incidence of hot flashes and leg cramps, and an increased risk of venous thromboembolic events.

The G protein-coupled estrogen receptor GPER/GPR30 as a regulator of cardiovascular function

Endogenous estrogens are important regulators of cardiovascular homeostasis in premenopausal women and delay the development of hypertension and coronary artery disease. These hormones act via three different estrogen receptors affecting both gene transcription and rapid signaling pathways in a complex interplay. In addition to the classical estrogen receptors ERα and ERβ, which are known mediators of estrogen-dependent vascular effects, a G protein-coupled estrogen receptor termed GPER that is expressed in the cardiovascular system has recently been identified. Endogenous human 17β-estradiol, selective estrogen receptor modulators (SERMs) including tamoxifen and raloxifene, and selective estrogen receptor downregulators (SERDs) such as ICI 182,780 are all agonists of GPER, which has been implicated in the regulation of vasomotor tone and protection from myocardial ischemia/reperfusion injury. As a result, understanding the individual role of ERα, ERβ, and GPER in cardiovascular function has become increasingly complex. With accumulating evidence that GPER is responsible for a variety of beneficial cardiovascular effects of estrogens, this receptor may represent a novel target to develop effective strategies for the treatment of cardiovascular diseases by tissue-specific, selective activation of estrogen-dependent molecular pathways devoid of side effects seen with conventional hormone therapy.

Effects of raloxifene on the renin-angiotensin-aldosterone system and blood pressure in hypertensive and normotensive osteoporotic postmenopausal women

AIM

An increase in blood pressure after menopause has been documented. The renin-angiotensin-aldosterone system (RAAS) plays a central role in the regulation of blood pressure and in the pathophysiology of hypertension. This study investigated the effects of raloxifene, a selective estrogen receptor modulator, on components of the RAAS and blood pressure in hypertensive and normotensive osteoporotic postmenopausal women.

METHODS

A total of 41 hypertensive or normotensive postmenopausal women with osteoporosis or osteopenia were divided into four groups. Eleven hypertensive and eight normotensive women received raloxifene hydrochloride (60 mg/day) p.o. for 6 months, and 12 hypertensive and 10 normotensive women did not receive raloxifene hydrochloride for 6 months. In all of the hypertensive women, blood pressure had been controlled prior to the start of the study using a variety of antihypertensive drugs other than angiotensin-converting enzyme (ACE) inhibitors, angiotensin (Ang)II type 1 receptor antagonists or diuretics. Plasma renin activity (PRA), serum ACE activity, plasma AngI, AngII and aldosterone concentrations, and blood pressure were measured before and 6 months after the start of the study.

RESULTS

No significant changes in PRA, ACE activity, or the AngI, AngII or aldosterone levels were observed in any of the groups. In all the groups, blood pressure remained unchanged.

CONCLUSION

Raloxifene may have no significant effect on the RAAS or blood pressure in hypertensive and normotensive osteoporotic postmenopausal women.

The effects of raloxifene hydrochloride on ocular hemodynamics and visual function

OBJECTIVE

To assess the comprehensive effects of raloxifene hydrochloride on retinal, choroidal and retrobulbar hemodynamics and on visual function in post-menopausal women.

DESIGN

Twenty-four post-menopausal women (age 55 +/- 3.8 years) were recruited for this cross-sectional study: 12 received placebo and 12 received raloxifene hydrochloride 60 mg once a day for 3 months. Baseline measurements of both groups included heart rate (HR), blood pressure (BP), visual acuity, contrast sensitivity and intraocular pressure (IOP) for both eyes. A comprehensive ocular blood flow (OBF) assessment was obtained for each patient in a randomly chosen study eye. Retinal blood flow data was obtained using confocal scanning laser Doppler flowmetry [Heidelberg Retinal Flowmeter (HRF)]. Color Doppler imaging (CDI) was used to assess retrobulbar hemodynamics in the ophthalmic, central retinal, short nasal and temporal posterior ciliary arteries. Baseline vision and hemodynamics in post-menopausal subjects were compared using paired Student's t tests, and the percentage change in baseline versus 3-month parameters was analyzed.

RESULTS

There were no statistically significant differences between 3 months of raloxifene therapy and placebo in terms of age, HR, arterial or mean BP, visual acuity, contrast sensitivity, IOP or retinal or retrobulbar blood flow.

CONCLUSION

Raloxifene therapy at 60 mg/day had no clinically significant impact on BP, IOP or OBF in post-menopausal women.

Effects of raloxifene therapy on plasma renin and aldosterone levels and blood pressure in postmenopausal women

OBJECTIVE

Blood pressure, which generally increases after menopause, is one of the best tools to characterize cardiovascular disease. The renin-aldosterone system plays a role in determining cardiovascular risk and the role of estrogen in the regulation of angiotensinogen gene expression and serum levels is well known. Raloxifene can induce endothelium-dependent vasodilation without affecting endothelium-independent vasorelaxation. The aim of the study was to investigate the effects of raloxifene on the renin-aldosterone system and blood pressure in postmenopausal women.

DESIGNS

Forty women, 54-59 years of age, in physiological menopause for 6 months to 4 years, were enrolled in the study and treated with raloxifene 60 mg/day for 6 months. All had blood pressure less than 130/85 mm Hg at the start of the study. The women were divided into two groups: the first (group A; 20 women) with normal blood pressure and the second (group B; 20 women) with previous high blood pressure treated with antihypertensive drugs, not angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.

RESULTS

No significant changes in plasma renin activity (PRA) or plasma concentrations of aldosterone were observed between the two groups after 6 months of raloxifene use. There was a slight reduction in PRA (11+/-4% for group A and 13+/-5% for group B) and in plasma levels of aldosterone (3.6+/-0.5% and 4.6+/-0.5%, respectively) with respect to basal values, but neither change was statistically significant.

CONCLUSIONS

The results of the present study show that raloxifene at 60 mg/day dose is well tolerated and has no clinical impact on blood pressure, PRA or aldosterone in postmenopausal women.

[Raloxifene in postmenopausal women]

Since the diffusion of the WHI's trial and MWS results, which reported a negative risk/benefit balance of hormone therapy, the management of postmenopausal women has deeply changed over the last 2-3 years. In particular, for the prevention of osteoporosis, the use of other efficient agents tends now to be more widely recommended rather than estrogens. The SERMs with raloxifene are new molecules that have estrogen agonist effects on bone and estrogen antagonist or neutral effects on endometrial and breast tissue. The efficacy of raloxifene to inhibit postmenopausal bone loss as well as to reduce the incidence of vertebral fractures has been demonstrated in women at high risk for osteoporosis through a large randomized placebo-controlled trial involving several thousands of postmenopausal women (MORE trial). Furthermore, the extraskeletal effects of raloxifene might represent an advantage for a global management approach of postmenopausal women, although to date, its exclusive indication is namely the prevention of osteoporosis. However, the estrogen antagonist effects of raloxifene on breast tissue as well as its good safety profile with regard to both the endometrium and the risk of heart diseases are likely to make raloxifene of particular interest for women around the age of 60 years old. Adverse events associated with raloxifene only included an increase in the absolute risk of venous thromboembolism in a comparable manner as with estrogen therapy. Also, its lack of efficacy in reducing hot flushes or preventing vaginal dryness may limit its use in young symptomatic postmenopausal women. Also, its lack of reimbursement in women with no prior fragility fracture must be taken into account.