Combination treatment with eldecalcitol (ED-71) and raloxifene improves bone mechanical strength by suppressing bone turnover and increasing bone mineral density in ovariectomized rats

Overview of the clinical efficacy and safety of eldecalcitol for the treatment of osteoporosis

Eldecalcitol (ELD) is a new oral analog of the active form of vitamin D with anti-resorptive properties. We conducted a meta-analysis to investigate the efficacy and safety of ELD in osteoporosis. Compared with alfacalcidol, ELD significantly lowered vertebral facture risk, increased bone mineral density, but also had a higher risk of hypercalciuria.

PURPOSE

This study aimed to investigate the efficacy and safety of eldecalcitol (ELD) in osteoporosis by examining fracture rates, bone mineral density (BMD), bone turnover markers, and adverse events as outcomes.

METHODS

PubMed, EMBASE, and Cochrane Library were searched up to July 20, 2020, to identify eligible randomized controlled trials. The odds ratio (OR) or weighted mean difference (WMD) with 95% confidence interval was calculated by the random-effects model.

RESULTS

ELD significantly increased lumbar BMD (WMD: 2.80; 95% CI: 1.60, 4.00; P < 0.001, 2 studies involved), total hip BMD (WMD: 2.11; 95% CI: 0.68, 3.55; P = 0.004, 2 studies involved), and femoral neck BMD (WMD: 1.78; 95% CI: 0.76, 2.79; P = 0.001, 1 study involved) compared with alfacalcidol. Moreover, ELD caused a significantly lower rate of vertebral fracture (OR: 0.52; 95% CI: 0.29-0.95; P = 0.034, 2 studies involved) than alfacalcidol, but did not lower the rate of non-vertebral facture (OR: 0.44; 95% CI: 0.06-3.05; P = 0.405, 2 studies involved) compared with alfacalcidol. ELD significantly reduced the percentage change in bone-specific alkaline phosphatase (WMD: - 15.40; 95% CI: - 20.30, - 10.60; P < 0.001, 1 study involved) and serum type I collagen C-telopeptide (WMD: - 38.50; 95% CI: - 50.00, - 27.10; P < 0.001, 1 study involved) as compared with alfacalcidol. ELD was also associated with higher risk of hypercalciuria compared with alfacalcidol (OR: 1.64; 95% CI: 1.22, 2.20; P = 0.001, 2 studies involved).

CONCLUSIONS

This systematic review indicated that ELD was superior than alfacalcidol for improving vertebral fracture risk and BMD. Further large-scale trials should be conducted to verify the long-term effects and safety of ELD in osteoporosis.

PROSPERO REGISTRATION NUMBER

CRD42020147518.

Bazedoxifene improves renal function and increases renal phosphate excretion in patients with postmenopausal osteoporosis

INTRODUCTION

Because aging is a predictor of renal insufficiency in the general population, renal function is a concern in postmenopausal patients undergoing treatment for osteoporosis. Although high serum phosphate concentration is a predictor of renal insufficiency, the effect of selective estrogen receptor modulator (SERM) on renal function and phosphate homeostasis remains to be established.

MATERIALS AND METHODS

We administered 20 mg/day bazedoxifene to 48 postmenopausal osteoporotic women who had been taking alfacalcidol for ≥ 6 months, and assessed lumbar spine bone mineral density (LS-BMD), renal function (by calculating estimated glomerular filtration rate using serum cystatin-C levels [eGFRcys] [range 38.0-98.2 mL/min/1.73 m²]), and phosphate homeostasis.

RESULTS

LS-BMD was significantly higher 6 months after the initiation of bazedoxifene administration. eGFRcys had increased by 3 months after initiation and was stable until 12 months. Serum phosphate gradually decreased after initiation, reaching statistical significance at 6 months. The changes in serum phosphate were also significant when the maximum tubular reabsorption rate of phosphate was normalized to glomerular filtration rate (TmP/GFR), indicating that bazedoxifene treatment reduces serum phosphate by increasing the urinary excretion of phosphate. The change in eGFRcys after the initiation of bazedoxifene was significantly negatively correlated with the change in serum phosphate, suggesting that a reduction in serum phosphate improves renal function.

CONCLUSION

Bazedoxifene improves renal function, possibly by increasing renal phosphate excretion, in postmenopausal osteoporotic women without severe renal insufficiency.

Further significant effects of eldecalcitol on bone resorption markers and bone mineral density in postmenopausal osteoporosis patients having undergone long-term bisphosphonate treatment

We investigated whether eldecalcitol has further significant effects on bone metabolic markers and bone mineral density (BMD) in osteoporosis patients having undergone long-term bisphosphonate treatment. Eldecalcitol treatment was initiated in 48 postmenopausal osteoporosis patients who had undergone bisphosphonate treatment with or without alfacalcidol treatment for more than 2 years (average period 6.3 years). Age, height, weight, total muscle volume, total fat volume, estimated glomerular filtration rate, and BMD at the lumbar spine, total hip, and distal third of the radius were measured as background data for each patient. Serum alkaline phosphatase, tartrate-resistant acid phosphatase 5b, calcium, and phosphate levels were measured at the baseline and 3 and 12 months after the initiation of eldecalcitol treatment, and BMD was measured at the baseline and 12 months after the initiation of eldecalcitol treatment. Tartrate-resistant acid phosphatase 5b level was significantly decreased at 3 and 12 months after the initiation of eldecalcitol treatment in comparison with the baseline level. There were no significant changes in alkaline phosphatase, calcium, or phosphate levels in comparison with the baseline levels. In addition, the lumbar spine BMD at 12 months after the initiation of treatment was significantly increased in comparison with the baseline level, although no significant changes in BMD at the total hip and distal third of the radius were observed. Eldecalcitol demonstrated significant effects in additionally decreasing the level of the bone resorption marker tartrate-resistant acid phosphatase 5b and increasing BMD at the lumbar spine, even in osteoporosis patients having undergone long-term bisphosphonate treatment.

Systematic review of raloxifene in postmenopausal Japanese women with osteoporosis or low bone mass (osteopenia)

Purpose

To systematically review the literature describing the efficacy, effectiveness, and safety of raloxifene for postmenopausal Japanese women with osteoporosis or low bone mass (osteopenia).

Materials and methods

Medline via PubMed and Embase was systematically searched using prespecified terms. Retrieved publications were screened and included if they described randomized controlled trials or observational studies of postmenopausal Japanese women with osteoporosis or osteopenia treated with raloxifene and reported one or more outcome measures (change in bone mineral density [BMD]; fracture incidence; change in bone-turnover markers, hip structural geometry, or blood–lipid profile; occurrence of adverse events; and change in quality of life or pain). Excluded publications were case studies, editorials, letters to the editor, narrative reviews, or publications from non-peer-reviewed journals; multidrug, multicountry, or multidisease studies with no drug-, country-, or disease-level analysis; or studies of participants on dialysis.

Results

Of the 292 publications retrieved, 15 publications (seven randomized controlled trials, eight observational studies) were included for review. Overall findings were statistically significant increases in BMD of the lumbar spine (nine publications), but not the hip region (eight publications), a low incidence of vertebral fracture (three publications), decreases in markers of bone turnover (eleven publications), improved hip structural geometry (two publications), improved blood–lipid profiles (five publications), a low incidence of hot flushes, leg cramps, venous thromboembolism, and stroke (12 publications), and improved quality of life and pain relief (one publication).

Conclusion

Findings support raloxifene for reducing vertebral fracture risk by improving BMD and reducing bone turnover in postmenopausal Japanese women with osteoporosis or osteopenia. Careful consideration of fracture risk and the risk–benefit profile of antiosteoporosis medications is required when managing patients with osteoporosis.

Eldecalcitol replaces endogenous calcitriol but does not fully compensate for its action in vivo

Calcitriol (1α,25-dihydroxyvitamin D3, 1α,25(OH)2D3) is an essential hormone that works in cooperation with parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF-23) to regulate calcium and phosphorus homeostasis. Previous in vivo studies in rats have shown that eldecalcitol, a vitamin D analog, is more active than calcitriol in stimulating calcium and phosphorus absorption in the intestine and in increasing serum FGF-23, but is not as active in suppressing blood PTH. However, those results are problematic because administration of exogenous eldecalcitol or calcitriol affects the synthesis and degradation of endogenous calcitriol, and competes for binding to vitamin D receptor (VDR) in target tissues. Therefore, we tried to evaluate the 'true biological activity in vivo' of each compound by comparing their biological activities with respect to their blood concentrations. In VDR gene knockout mice, calcitriol and eldecalcitol did not affect either serum or urinary calcium levels, and also did not induce the expression of target genes. These results indicate that the actions of eldecalcitol are mediated by VDR. In normal rats, concentrations of both calcitriol and eldecalcitol in the blood increased dose-dependently and had a linear correlation with administered dosage. The concentration of calcitriol in the blood was reduced by eldecalcitol treatment, falling to below the limit of detection at 0.1μg/kg eldecalcitol. Based on the concentration of each compound in the blood, eldecalcitol had approximately 1/4 to 1/7 the activity of calcitriol to increase serum calcium, FGF-23, and urinary calcium excretion, and to suppress blood PTH. Eldecalcitol dose-dependently increased urinary phosphorus excretion and reduced serum phosphorus. However, calcitriol did not change serum phosphorus. In accordance with serum chemistry and hormones, a concentration of eldecalcitol in the blood of 3-8 times that of calcitriol was required to stimulate target gene expressions in the kidneys (VDR, TRPV5, and calbindin-D28k) and bone (VDR, FGF-23, and RANKL). On the other hand, the blood concentrations of eldecalcitol needed to stimulate target genes in the intestine (TRPV6, calbindin-D9k, and VDR) were comparable to those of calcitriol. These results indicate that oral administration of eldecalcitol stimulates target gene expression in the intestine similarly to calcitriol, but to a much lesser extent than calcitriol in the kidneys and bones. The major finding of the present study is that eldecalcitol suppresses endogenous calcitriol and replaces it. However, it may not fully compensate for the action of calcitriol in vivo. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

Eldecalcitol for the treatment of osteoporosis

Eldecalcitol (1α, 25-dihydroxy-2β-[3-hydroxypropyloxy] vitamin D₃; ED-71) is a new analog of the active form of vitamin D. Eldecalcitol has recently been approved for the treatment of osteoporosis in Japan. In addition to regulation of calcium metabolism carried out by conventional vitamin D analogs, eldecalcitol possesses a strong inhibitory effect on bone resorption and causes a significant increase in bone mineral density. A Phase III clinical trial on osteoporosis showed that eldecalcitol reduced the incidence of new vertebral fractures over 3 years by 26% compared with alfacalcidol. Although the overall risk of nonvertebral fractures was not reduced by eldecalcitol, the risk of wrist fracture was decreased significantly in the eldecalcitol group (71%) compared with the alfacalcidol group. The serum level of 25-hydroxyvitamin D (25[OH]D) was normalized by supplementation of native vitamin D in this trial, so the desirable effects on bone by eldecalcitol were considered to be derived from its distinctive pharmacological action. Increased blood calcium was observed in 21% of patients treated with eldecalcitol, and hypercalcemia (>11.5 mg/dL) occurred in 0.4% of eldecalcitol recipients, so serum calcium concentration should be monitored after starting eldecalcitol treatment. Eldecalcitol has dual effects on the metabolism of bone and calcium and is useful for the treatment of osteoporosis, especially for elderly patients (who frequently suffer from vitamin D deficiency). This article reviews the clinical efficacy and safety of eldecalcitol in the treatment of osteoporosis.