Comparison of antiresorptive activities of ipriflavone, an isoflavone derivative, and elcatonin, an eel carbocalcitonin

Efficacy and safety of elcatonin in postmenopausal women with osteoporosis: a systematic review with network meta-analysis of randomized clinical trials

The present systematic review aimed to evaluate bone mineral density (BMD) change and complication rates of elcatonin on treating postmenopausal osteoporosis. The result confirmed efficacy of elcatonin and safety in combination therapies of elcatonin (C-E).

INTRODUCTION

Postmenopausal osteoporosis is an important issue in global aging trends. One treatment of osteoporosis is elcatonin, a kind of calcitonin. However, it has been challenged for long time because of safety. Many trials investigated on this topic, but they were designed differently. Those designs can be categorized in monotherapy of elcatonin (M-E) and C-E. Unfortunately, no synthesized evidence dealt this topic.

METHODS

This study systematically identified target trials from six important databases and only included randomized controlled trial for synthesis. Two investigators assessed quality of eligible trials using the Cochrane Risk of Bias Tool, and they independently extracted data. Network meta-analysis performed Peto odds ratio (POR, used for dealing with zero cell) or weighted mean difference (WMD, for continuous data) with 95% confidence intervals (CI) and consistency H.

RESULTS

Sixteen trials recruiting 2754 women with postmenopausal osteoporosis were included in our study. Elcatonin therapies and non-elcatonin medications had comparable fracture rates and bone mineral density change. Yet, C-E (WMD, - 18.93; 95% CI, - 23.97 to - 13.89) and M-E (WMD, - 13.72; 95% CI, - 19.51 to - 7.94) had significantly lower pain score than non-elcatonin medications. However, M-E (POR = 8.413, 95% CI, 2.031 to 34.859) and non-elcatonin medication (Peto OR, 7.450; 95% CI, 1.479 to 37.530) had significantly higher complication rates than placebo. No evidence detected inconsistency and small study effect in this network model.

CONCLUSIONS

Based on current evidence, C-E may be considered for treating postmenopausal osteoporosis because it benefits on pain relief and complications. Moreover, it shows comparable fracture rate and bone mineral density change as compared with anti-osteoporosis and calcium supplements. Nevertheless, further trials are needed to investigate formula and dosages of elcatonin.

Grape seed extract supplement increases bone callus formation and mechanical strength: an animal study

Background

The positive effects of grape seed proanthocyanidin extract (GSPE) on bone health, which is a potent antioxidant, are known but its effects on fracture healing are not sufficiently covered in the literature. This study aims to investigate the effects of GSPE on fracture healing and biomechanics of healing bone.

Materials and methods

Sixty-four adult Wistar-Albino male rats were divided into 8 groups of 8 animals in each group. Osteotomy was performed to the right femurs of all groups except the negative control (G1) and positive control (G2) groups, and intramedullary Kirchner wire was used for fixation. GSPE was given to half of the rats (G2-G4-G6-G8) 100 mg/kg/day by oral gavage. The rats were sacrificed on the tenth (G3–G4), twentieth (G5–G6), and thirtieth (G1–G2–G7–G8) days, respectively, and histopathological, radiological, and biomechanical examinations were performed.

Results

Histopathological examination of the specimens from the callus tissues revealed that bone healing was more prominent in the groups supplemented with GSPE (G4, G6, G8). There was a statistically significant improvement in radiological recovery scores and callus volumes in groups with GSPE. When biomechanical strengths were evaluated, it was found that GSPE increased bone strength not only in fracture groups but also in the positive control group (G2).

Conclusions

As a result, this study showed that GSPE, a potent anti-oxidant, had a positive effect on bone healing and improved mechanical strength of the healing bone.

A randomized, double-blind, placebo-controlled study of once weekly elcatonin in primary postmenopausal osteoporosis

OBJECTIVE

Very few reports have described changes in bone mineral density (BMD) with long-term, once weekly administration of elcatonin, and its effects in reducing incident fractures remain unverified. Therefore, the efficacy and safety of once weekly elcatonin were examined over a 3 year period.

METHODS

This was a multicenter, double-blinded, randomized, placebo-controlled study. Postmenopausal women with primary osteoporosis received either 20 units of elcatonin (EL group, n = 433) or placebo (P group, n = 436) once a week for 144 weeks (3 years) intramuscularly. The primary endpoint was the incidence of new vertebral fractures at 24, 48, 72, 96, 120, and 144 weeks after the start. Secondary endpoints were the incidence of non-vertebral fractures, changes in lumbar, hip total and femoral neck BMD, and the incidence of adverse drug reactions (ADRs).

RESULTS

No significant reduction in the incidence of new vertebral fractures was found in the EL group. The percentage increase in lumbar BMD was significantly higher in the EL group from 24 weeks to the last administration. Although the EL group showed tendencies toward smaller decreased hip total and femoral neck BMD, no significant differences were observed between groups. The incidence of ADRs was significantly greater in the EL group, although these have all been previously reported and no new safety concerns were identified.

CONCLUSIONS

Once weekly injection of 20 units of elcatonin significantly increased lumbar BMD over a 3 year period and did not cause any safety problems, but no significant reduction in the incidence of vertebral or non-vertebral fractures was demonstrated.

Eel calcitonin (elcatonin) suppressed callus remodeling but did not interfere with fracture healing in the femoral fracture model of cynomolgus monkeys

We investigated the effect of eel calcitonin (elcatonin) on the process of fracture repair in the osteotomized femur of cynomolgus monkeys, since they possess a Haversian remodeling system similar to that of humans. Alendronate was used for comparison. Twenty female cynomolgus monkeys (Macaca fascicularis), aged 18-22 years, were allocated into five groups: control (CNT, n = 4), low-dose elcatonin group (0.5 U/kg; ELL, n = 4), high-dose elcatonin group (5 U/kg; ELH, n = 4), low-dose alendronate group (10 microg/kg; ALL, n = 4) and high-dose alendronate group (100 microg/kg; ALH, n = 4). All animals were given subcutaneous injections twice a week for 3 weeks. Then fracture was produced surgically by transversely cutting the midshaft of the right femur and fixing with stainless steel plate. After fracture, treatments were continued until sacrifice at 26 weeks after surgery. The femora were assessed by micro CT, contact microradiograph, three-point bending mechanical test and histomorphometry. Micro CT showed that callus sizes in elcatonin-treated groups were similar to CNT, whereas alendronate-treated groups had larger calluses than those in the CNT and elcatonin-treated groups. Fracture lines almost disappeared in the CNT and elcatonin-treated groups but remained clear in the alendronate-treated groups. Total area did not differ significantly between the elcatonin-treated groups and the CNT but was significantly greater in the ALH compared to the CNT and elcatonin-treated groups, due to increased callus area in the ALH group. Callus remodeling was less suppressed in the elcatonin-treated groups than in the alendronate-treated groups when compared with callus remodeling in the CNT. Although no significant differences in structural mechanical properties such as ultimate load, stiffness and work to failure were found among all groups, ultimate stress was significantly reduced in the ALH group compared with CNT and ELL groups. In conclusion, mild suppression of callus remodeling by elcatonin did not impair overall fracture healing process. In contrast, alendronate delayed structural fracture healing process by strongly suppressing callus remodeling.

The effects of calcitonin on plasma calcium levels and bone metabolism in the fresh water teleost Channa punctatus

Administration of salmon calcitonin (sCT) caused significant reduction in total and ultrafiltrable plasma calcium content in the plasma of a fresh water female teleost Channa punctatus. A time-bound analysis on the effect of sCT showed a highly significant short duration reduction in total and ultrafiltrable plasma calcium content in fish kept in normal tap water and low-calcium water and a moderate hypocalcemia in fish kept in high-calcium water. Sexually immature adult fish showed a greater response than the sexually mature ones. Using tartrate-resistant acid phosphatase (TRACP) and alkaline phosphatase (ALP) activities in plasma and hydroxyproline (HYP) excretion in urine, the effect of sCT on the inhibition of bone calcium resorption were examined. In both sexually mature and immature adult fish, kept in normal tap water, sCT significantly suppressed TRACP and ALP activities in plasma and excretion of HYP in urine within 2-6 h with a maximum at 4 h after injection. Salmon CT treatment to sexually immature adult fish caused significant increase in skeletal bone calcium concentration. Taken together, all this information indicates that CT in a fresh water female teleost is an effective regulator of plasma calcium levels, and its action, at least in part, operates through inhibition of bone calcium resorption.

Effects of grape seed proanthocyanidins extract on mandibles in developing rats

OBJECTIVE

Grape seed proanthocyanidins extract (GSPE), a flavonoid, has a beneficial effect on physical health, which may include the health of bone. The purpose of the present study was to investigate the effects of GSPE on mandibular bone by examining trabecular and cortical bone density, mineral content, and non-invasive bone strength in low-calcium diet rats.

MATERIALS AND METHODS

Wistar male rats at 5 weeks old (n = 40) were divided into control (A), low-calcium diet (B), low-calcium diet plus standard diet (C), and low-calcium diet plus standard diet with supplementary GSPE (D) groups. Following 3 weeks of a calcium-restricted diet, group D rats were given 3 mg of GSPE as supplement in 100 g of a standard diet for the next 3 weeks. Following the 6-week experimental period, mandibular bones were examined using peripheral quantitative computed tomography (pQCT).

RESULTS

There were no significant differences in body weight or trabecular bone area among the four groups. Trabecular bone density, and trabecular bone mineral content, cortical bone density, cortical bone cross-sectional area, and cortical bone mineral content were significantly higher in group D than in C. Further, Stress-strain index (SSI) values of xSSI and ySSI in group D were significantly higher than in C, although there was no significant difference in pSSI value between those two groups.

CONCLUSION

Our results suggest that GSPE treatment caused an increase in both bone formation and bone strength in rat mandibles.

Evidence of estrogenic effect by the three-month-intervention of isoflavone on vaginal maturation and bone metabolism in early postmenopausal women

Objective of the present study is to determine the estrogenic effect of isoflavone on vaginal epithelia and bone metabolism in early postmenopausal women. Twenty-two postmenopausal women were randomly assigned to either a group that was given isoflavone extract (61.8 mg) for three months or a control group that was given placebo. We measured the L2-4 bone mineral density (BMD) before and 3 months after treatment by dual X-ray absorptiometry (DXA). Blood and urine samples were obtained from the women before and 3 months after treatment. We measured FSH using radioimmunoassay and, urinary pyridinoline and deoxypyridinoline levels by HPLC. For endocrine cytology, vaginal smears were collected before and 3 months after the treatment. Three months after the treatment, the serum FSH levels and the BMD values did not significantly differ between the two groups. Urinary excretion of isoflavone was significantly higher in the group given isoflavone compared with that given placebo (p<0.03). Numbers of parabasal and intermediate types of cells were significantly decreased (58.2 +/- 12.4% to 25.0 +/- 10.7%; p<0.05) and increased (24.1 +/- 8.7% to 63.7 +/- 10.7%; p<0.05), respectively in the isoflavone group, but remained unchanged in the control group. Urinary pyridinoline excretion was significantly decreased (49.6% vs. before, p<0.01 by paired t-test) in the isoflavone group. The intake of 60 mg of isoflavone daily for 3 months produced maturational changes of vaginal epithelia without affecting serum FSH levels, and could possibly slow down bone turnover rates as judged by decreased urinary pyridinoline excretion.

New approaches to the treatment of osteoporosis

Under physiological conditions, maintenance of skeletal mass is the result of a tightly coupled process of bone formation and bone resorption. Disease states, osteoporosis included, arise when this delicate balance is disrupted such as in menopause, when estrogen levels decrease dramatically corresponding with the cessation of ovarian function. Current therapies for the treatment of osteoporosis, including estrogen replacement therapy, selective estrogen receptor modulators and bisphosphonates, are primarily based on blunting the resorption component of bone homeostasis. Although selective estrogen receptor modulators offer bone protection without the side effects of estrogen replacement therapy, there are some areas of improvement for the current generation of selective estrogen receptor modulators; particularly in reducing their antagonistic properties in the central nervous system that lead to vasomotor symptoms. There are few therapies that are focused on increasing bone formation, but they offer promising avenues in which to expand the repertoire of drugs to restore bone mass. Selective androgen receptor modulators, parathyroid hormone analogs, oxytocin analogs and statins, all with improved pharmacological properties in bone, are among the potential approaches to eliciting anabolic effects in the skeleton.