The effects of bazedoxifene on bone structural strength evaluated by hip structure analysis

Effect of Tissue-Selective Estrogen Complex on Hip Structural Geometry in Postmenopausal Women: A 12-Month Study

BACKGROUND

Hip structural analysis (HSA) is a method for evaluating bone geometry reflecting bone structural and biomechanical properties. However, tissue-selective estrogen complex (TSEC) treatment effects on HSA have not been investigated.

OBJECTIVE

This study was performed to evaluate the effect of TSEC treatment on hip geometry in postmenopausal Korean women. The treatment was given for 12 months, and hip geometry was measured by HSA.

MATERIALS AND METHODS

A total of 40 postmenopausal women who received TSEC containing conjugated estrogen 0.45 mg and bazedoxifene 20 mg for treating vasomotor symptoms were included in this retrospective cohort study. The changes in bone mineral density and parameters of HSA including the outer diameter, cross-sectional area, cross-sectional moment of inertia, cortical thickness, section modulus, and buckling ratio as determined by dual-energy X-ray absorptiometry were compared before and after 12 months of TSEC treatment.

RESULTS

Mean age and years since menopause were 55.1 and 4.5 years, respectively. Total hip bone mineral density significantly increased by 0.74% after treatment (P=0.011). The changes in HSA were mainly demonstrated in the narrow femoral neck: cross-sectional area (P=0.003) and cortical thickness (P<0.001) increased significantly. For the shaft region, only SM decreased significantly after treatment (P=0.009). However, most parameters did not change significantly with TSEC treatment in the intertrochanteric and shaft regions.

CONCLUSIONS

Our findings demonstrate that 12 months of TSEC treatment could improve bone geometry as measured by HSA. The findings suggest that TSEC might be an interesting option for the prevention of fracture as well as osteoporosis in postmenopausal women.

Estrogen Regulates the Satellite Cell Compartment in Females

Skeletal muscle mass, strength, and regenerative capacity decline with age, with many measures showing a greater deterioration in females around the time estrogen levels decrease at menopause. Here, we show that estrogen deficiency severely compromises the maintenance of muscle stem cells (i.e., satellite cells) as well as impairs self-renewal and differentiation into muscle fibers. Mechanistically, by hormone replacement, use of a selective estrogen-receptor modulator (bazedoxifene), and conditional estrogen receptor knockout, we implicate 17β-estradiol and satellite cell expression of estrogen receptor α and show that estrogen signaling through this receptor is necessary to prevent apoptosis of satellite cells. Early data from a biopsy study of women who transitioned from peri- to post-menopause are consistent with the loss of satellite cells coincident with the decline in estradiol in humans. Together, these results demonstrate an important role for estrogen in satellite cell maintenance and muscle regeneration in females.

Collins et al. show the loss of estrogen in female mice and post-menopausal women leads to a decrease in skeletal muscle stem cells. Using muscle stem cell-specific mutants, it was demonstrated that ERα is necessary for satellite cell maintenance, self-renewal, and protection from apoptosis, thereby promoting optimal muscle regeneration.

Bazedoxifene for the treatment of osteoporosis

Introduction: Bazedoxifene (BZD) is a third-generation selective estrogen receptor modulator approved for the treatment of postmenopausal osteoporosis with additional favorable effects in lipids, uterine and breast tissue. Areas covered: In this review, the authors outline clinical data regarding the efficacy, safety, and tolerability of continuous BZD administration up to seven years in randomized, placebo-controlled, phase III clinical trials. Long-term treatment with BZD for postmenopausal osteoporosis is generally safe and well tolerated. BZD achieves small but significant increases in the bone mineral density of the lumbar spine but not the total hip. In addition, BZD reduces significantly the risk of vertebral fractures but not of non-vertebral and hip fractures, with the exception of high fracture risk postmenopausal women in whom BZD significantly reduces non-vertebral fractures. Expert opinion: BZD does not seem to offer significant advantages over the other available antiresorptive agents. However, considering the need for long-term management of osteoporosis, BZD may have a place in the long-term therapeutic planning of the disease.

Bazedoxifene/conjugated estrogens in combination with leuprolide for the treatment of endometriosis

Bazedoxifene/conjugated estrogens can be used with leuprolide as effective add-back therapy in premenopausal women with endometriosis without unwanted stimulation of the breasts, CNS (Central Nervous System), or endometrium. Bazedoxifene/conjugated estrogens may be an effective progestin-free alternative to traditional add-back therapies.

Are estrogen-related drugs new alternatives for the management of osteoarthritis?

Osteoarthritis (OA) is a chronic degenerative disease involving multiple physiopathological mechanisms. The increased prevalence of OA after menopause and the presence of estrogen receptors in joint tissues suggest that estrogen could help prevent development of OA. This review summarizes OA research with a focus on the effects of estrogen and selective estrogen receptor modulators (SERMs). Preclinical studies and clinical trials of estrogen therapy have reported inconsistent results. However, almost all studies assessing SERM treatment have obtained more consistent and favorable effects in OA with a relatively safety and tolerability profiles. At present, some SERMs including raloxifene and bazedoxifene have been approved for the treatment of osteoporosis. In summary, estrogen-related agents may exert both a direct effect on subchondral bone and direct and/or indirect effects upon the surrounding tissues, including the articular cartilage, synovium, and muscle, to name a few. Estrogen and SERMs may be particularly favorable for postmenopausal patients with early-stage OA or osteoporotic OA, a phenotype defined by reduced bone mineral density related to high remodeling in subchondral bone. At present, no single drug exists that can prevent OA progression. Although estrogen-related drugs provide insight into the continued work in the field of OA drug administration, further research is required before SERMs can become therapeutic alternatives for OA treatment.

Role of ERαMISS in the Effect of Estradiol on Cancellous and Cortical Femoral Bone in Growing Female Mice

Estrogen receptor-α (ERα) acts primarily in the nucleus as a transcription factor involving two activation functions, AF1 and AF2, but it can also induce membrane-initiated steroid signaling (MISS) through the modulation of various kinase activities and/or secondary messenger levels. Previous work has demonstrated that nuclear ERα is required for the protective effect of the estrogen 17β-estradiol (E2), whereas the selective activation of ERαMISS is sufficient to confer protection in cortical but not cancellous bone. The aim of this study was to define whether ERαMISS is necessary for the beneficial actions of chronic E2 exposure on bone. We used a mouse model in which ERα membrane localization had been abrogated due to a point mutation of the palmitoylation site of ERα (ERα-C451A). Alterations of the sex hormones in ERα-C451A precluded the interpretation of bone parameters that were thus analyzed on ovariectomized and supplemented or not with E2 (8 μg/kg/d) to circumvent this bias. We found the beneficial action of E2 on femoral bone mineral density as well as in both cortical and cancellous bone was decreased in ERα-C451A mice compared with their wild-type littermates. Histological and biochemical approaches concurred with the results from bone marrow chimeras to demonstrate that ERαMISS signaling affects the osteoblast but not the osteoclast lineage in response to E2. Thus, in contrast to the uterine and endothelial effects of E2 that are specifically mediated by nuclear ERα and ERαMISS effects, respectively, bone protection is dependent on both, underlining the exquisite tissue-specific actions and interactions of membrane and nuclear ERα.

Twelve-Minute Daily Yoga Regimen Reverses Osteoporotic Bone Loss

Objective:

Assess the effectiveness of selected yoga postures in raising bone mineral density (BMD).

Methods:

Ten-year study of 741 Internet-recruited volunteers comparing preyoga BMD changes with postyoga BMD changes.

Outcome Measures:

Dual-energy x-ray absorptiometric scans. Optional radiographs of hips and spine and bone quality study (7 Tesla).

Results:

Bone mineral density improved in spine, hips, and femur of the 227 moderately and fully compliant patients. Monthly gain in BMD was significant in spine (0.0029 g/cm², P = .005) and femur (0.00022 g/cm², P = .053), but in 1 cohort, although mean gain in hip BMD was 50%, large individual differences raised the confidence interval and the gain was not significant for total hip (0.000357 g/cm²). No yoga-related serious injuries were imaged or reported. Bone quality appeared qualitatively improved in yoga practitioners.

Conclusion:

Yoga appears to raise BMD in the spine and the femur safely.