Novel insights into actions of bisphosphonates on bone: differences in interactions with hydroxyapatite

Patient satisfaction and efficacy of switching from weekly bisphosphonates to monthly minodronate for treatment and prevention of glucocorticoid-induced osteoporosis in Japanese patients with systemic rheumatic diseases: a randomized, clinical trial

The randomized, clinical trial demonstrated that switching to monthly minodronate from weekly alendronate and risedronate provides greater increases in patients' satisfaction and bone mineral density and more substantial decreases in a bone resorption marker than continuing weekly alendronate and risedronate in patients with systemic rheumatic diseases on glucocorticoid therapy.

PURPOSE

Osteoporosis and associated fractures are major concerns for patients with systemic rheumatic diseases on long-term glucocorticoid therapy. Bisphosphonates increase bone mineral density (BMD) and reduce the frequency of vertebral fractures, but they are associated with poor adherence. The effects of monthly oral minodronate on patients' satisfaction, BMD, and bone turnover markers were investigated in patients with systemic rheumatic diseases on glucocorticoids and weekly oral alendronate or risedronate.

METHODS

Study patients with systemic rheumatic diseases on oral glucocorticoids and weekly alendronate 35 mg or risedronate 17.5 mg were randomly assigned either to switch to minodronate 50 mg every 4 weeks or to continue the currently taking weekly bisphosphonate for 52 weeks after a 24-week run-in period.Patients were stratified by hospital site, sex, and menopausal status in women at enrollment. The primary endpoint was the difference between the proportions of patients who responded very satisfactory or satisfactory for the current bisphosphonate therapy at weeks 48 and 76 between the two groups. Secondary endpoints included percentage changes in lumbar spine BMD and bone turnover markers from the time of starting allocated treatment.

RESULTS

Monthly minodronate was superior to weekly alendronate or risedronate for patients' satisfaction, the increase of lumbar spine BMD, and suppression of serum tartrate-resistant acid phosphatase 5b at week 76.

CONCLUSIONS

Monthly minodronate is more acceptable and may be more effective than weekly alendronate or risedronate for prevention and treatment of bone loss in patients with systemic rheumatic diseases on glucocorticoid therapy.

Influence of pH on osteoclasts treated with zoledronate and alendronate

OBJECTIVES

The objectives of this study were to analyze the effect of pH on the growth and activity of osteoclasts treated with different doses of two nitrogen-containing BPs, zoledronate and alendronate.

MATERIALS AND METHODS

Murine osteoclasts cultured on dentine disks were treated with zoledronate (50 or 500 nM) or alendronate (500 or 5 μM) at two different pH values (7.4 or 7.0). Osteoclasts were counted with transmitted light microscopy, apoptosis/necrosis was studied with flow cytometry and confocal microscopy, and resorption pit number and depth were calculated using reflected light and scanning electron microscopy.

RESULTS

The osteoclast count on dentine disks was significantly (p < 0.001) reduced by zoledronate or alendronate treatment at pH 7.0 in comparison to treatment with the same doses at pH 7.4 and untreated disks (controls). The percentage of apoptotic cells was significantly increased by treatment with 500 nM zoledronate or 5 μM alendronate at pH 7.0 in comparison to the same doses at pH 7.4. The number and depth of resorption pits were significantly lower in disks treated at each BP dose studied than in untreated controls at pH 7.0.

CONCLUSIONS

Zoledronate and alendronate at therapeutic doses have an adverse effect on the viability and resorptive activity of osteoclasts when the local medium pH is reduced.

CLINICAL RELEVANCE

These findings suggest that periodontal or peri-implant oral cavity infection may be a key trigger of the cascade of events that lead to BRONJ.

Effects of discontinuing oral bisphosphonate treatments for postmenopausal osteoporosis on bone turnover markers and bone density

The antiresorptive potency varies between different bisphosphonates. We investigated the effect of stopping oral bisphosphonate treatment for postmenopausal osteoporosis (ibandronate, alendronate, risedronate) on BTMs and BMD. After stopping treatment, all three groups showed an increase in BTMs and a decrease in hip BMD; however, none returned to pre-treatment baseline values.

INTRODUCTION

Bisphosphonates (BPs) continue to suppress bone turnover markers (BTMs) after treatment has stopped, leading to the suggestion that a pause in treatment could be considered for low-risk patients. Indirect comparisons suggest that after cessation of treatment, the effects on bone may differ between drugs. We investigated the effects of stopping oral BP treatments for postmenopausal osteoporosis on BTMs and bone mineral density (BMD).

METHODS

We studied postmenopausal osteoporotic women who had previously taken part in a 2-year randomised study of three oral BPs (ibandronate, alendronate, or risedronate). At the end of the study, women with hip BMD T-score > - 2.5 and considered clinically appropriate to discontinue treatment were invited to participate in a further 2-year observational study. Biochemical response was assessed using BTMs, and BMD was measured by dual-energy X-ray absorptiometry.

RESULTS

All BTMs increased after treatment withdrawal but remained below the pre-treatment baseline with less suppression of BTMs for the risedronate group compared to alendronate and ibandronate up to 48 weeks. There was no difference between the BP groups 96 weeks after stopping treatment. The change in BMD during the 96 weeks after stopping treatment was - 1.6% (95% CI - 1.9 to - 1.2, P < 0.001) for the total hip and - 0.6% (95% CI - 1.1 to - 0.2, P = 0.17) at the lumbar spine with no difference between the three BP groups (P = 0.85 and P = 0.48, respectively).

CONCLUSION

For all treatment groups, there was an increase in BTMs and a decrease in hip BMD after stopping BPs for 2 years; however, none returned to pre-treatment baseline values.

Removal of matrix-bound zoledronate prevents post-extraction osteonecrosis of the jaw by rescuing osteoclast function

Unlike other antiresorptive medications, bisphosphonate molecules accumulate in the bone matrix. Previous studies of side-effects of anti-resorptive treatment focused mainly on systemic effects. We hypothesize that matrix-bound bisphosphonate molecules contribute to the pathogenesis of bisphosphonate-related osteonecrosis of the jaw (BRONJ). In this study, we examined the effect of matrix-bound bisphosphonates on osteoclast differentiation in vitro using TRAP staining and resorption assay, with and without pretreatment with EDTA. We also tested the effect of zoledronate chelation on the healing of post-extraction defect in rats. Our results confirmed that bisphosphonates bind to, and can be chelated from, mineralized matrix in vitro in a dose-dependent manner. Matrix-bound bisphosphonates impaired the differentiation of osteoclasts, evidenced by TRAP activity and resorption assay. Zoledronate-treated rats that underwent bilateral dental extraction with unilateral EDTA treatment showed significant improvement in mucosal healing and micro-CT analysis on the chelated sides. The results suggest that matrix-bound bisphosphonates are accessible to osteoclasts and chelating agents and contribute to the pathogenesis of BRONJ. The use of topical chelating agents is a promising strategy for the prevention of BRONJ following dental procedures in bisphosphonate-treated patients.

Bone-seeking agents for the treatment of bone disorders

The targeting and delivery of therapeutic and diagnostic agents to bone tissue presents both a challenge and opportunity. Osteoporosis, Paget's disease, cancer, and bone metastases are all skeletal diseases whose treatment would benefit from new targeted therapeutic strategies. Osteoporosis, in particular, is a very prevalent disease, affecting over one in three women and one in five men in Canada alone with the cost to the healthcare system estimated at over $2.3 billion in 2010. Bone tissue is often considered a rigid structure when in reality there is a process of continuous remodeling that takes place via complex endocrine-regulated cell signaling pathways in addition to the signaling pathways unique to bone tissue. It is these specific boneremodeling processes that provide unique targeting opportunities but also present a number of challenges.

Minodronate for the treatment of osteoporosis

Minodronate is a third-generation bisphosphonate that was developed and approved for clinical use in osteoporosis therapy in Japan. The mechanism of action for suppressing bone resorption is the inhibition of farnesyl pyrophosphate synthase, a key enzyme in the mevalonic acid metabolic pathway of osteoclasts, to induce apoptosis of the cells. Minodronate is the strongest inhibitor of bone resorption among the currently available oral bisphosphonates. Large randomized, placebo-controlled, double-blind clinical trials have revealed an increase in bone mineral density of both the lumbar spine and femoral neck over 3 years of daily minodronate therapy and risk reduction in vertebral fractures over 2 years of therapy. The increase in bone mass and the prevention of vertebral fractures are similar to those with alendronate or risedronate. The incidence of adverse events, especially gastrointestinal disturbance, is the same as or less than that with weekly or daily alendronate or risedronate. The unique mechanism of action of minodronate via the inhibition of the P2X(2/3) receptor compared with other bisphosphonates may be an advantage in reducing low back pain in patients with osteoporosis. The monthly regimen of minodronate, introduced in 2011, is expected to have better patient adherence and longer persistence. In experimental animal models, minodronate preserved, or even ameliorated, bone microarchitectures, including microcracks and perforation of the trabeculae in the short term. The lowest incidence of bisphosphonate-related osteonecrosis of the jaw among all bisphosphonates and the lack of atypical femoral fractures attributed to its use to date, however, are partly because only a smaller population used minodronate than those using other bisphosphonates. To date, minodronate is available only in Japan. Hip fracture risk reduction has not been verified yet. More clinical studies on minodronate and its use in osteoporosis treatment, with a large number of subjects, should be conducted to verify hip fracture risk reduction and long-term results.

Star-shaped poly(oligoethylene glycol) copolymer-based gels: Thermo-responsive behaviour and bioapplicability for risedronate intranasal delivery

The aim of this work was to obtain an intranasal delivery system with improved mechanical and mucoadhesive properties that could provide prolonged retention time for the delivery of risedronate (RS). For this, novel in situ forming gels comprising thermo-responsive star-shaped polymers, utilizing either polyethylene glycol methyl ether (PEGMA-ME 188, Mn 188) or polyethylene glycol ethyl ether (PEGMA-EE 246, Mn 246), with polyethylene glycol methyl ether (PEGMA-ME 475, Mn 475), were synthesized and characterized. RS was trapped in the selected gel-forming solutions at a concentration of 0.2% w/v. The pH, rheological properties, in vitro drug release, ex vivo permeation as well as mucoadhesion were also examined. MTT assays were conducted to verify nasal tolerability of the developed formulations. Initial in vivo studies were carried out to evaluate anti-osteoporotic activity in a glucocorticoid induced osteoporosis model in rats. The results showed successful development of thermo-sensitive formulations with favorable mechanical properties at 37 °C, which formed non-irritant, mucoadhesive porous networks, facilitating nasal RS delivery. Moreover, sustained release of RS, augmented permeability and marked anti-osteoporotic efficacy as compared to intranasal (IN) and intravenous (IV) RS solutions were realized. The combined results show that the in situ gels should have promising application as nasal drug delivery systems.

Insights into the bisphosphonate holiday: a preliminary FTIRI study

Bone composition evaluated by FTIRI analysis of iliac crest biopsies from post-menopausal women treated with alendronate for 10 years, continuously or alendronate for 5 years, followed by a 5-year alendronate-holiday, only differed with the discontinued biopsies having increased cortical crystallinity and heterogeneity of acid phosphate substitution and decreased trabecular crystallinity heterogeneity.

INTRODUCTION

Bisphosphonates (BP) are the most commonly used and effective drugs to prevent fragility fractures; however, concerns exist that prolonged use may lead to adverse events. Recent recommendations suggest consideration of a BP "holiday" in individuals taking long-term BP therapy not at high risk of fracture. Data supporting or refuting this recommendation based on bone quality are limited. We hypothesized that a "holiday" of 5 years would cause no major bone compositional changes.

METHODS

We analyzed the 31 available biopsies from the FLEX-Long-term Extension of FIT (Fracture Intervention Trial) using Fourier transform infrared imaging (FTIRI). Biopsies from two groups of post-menopausal women, a "Continuously treated group" (N = 16) receiving alendronate for ~ 10 years and a "Discontinued group" (N = 15), alendronate treated for 5 years taking no antiresorptive medication during the following 5 years. Iliac crest bone biopsies were provided at 10 years.

RESULTS

Key FTIRI parameters, mineral-to-matrix ratio, carbonate-to-phosphate ratio, acid phosphate substitution, and collagen cross-link ratio as well as heterogeneity of these parameters were similar for Continuously treated and Discontinued groups in age-adjusted models. The Discontinued group had 2% greater cortical crystallinity (p = 0.01), 31% greater cortical acid phosphate heterogeneity (p = 0.02), and 24% lower trabecular crystallinity heterogeneity (p = 0.02).

CONCLUSIONS

Discontinuation of alendronate for 5 years did not affect key FTIRI parameters, supporting the hypothesis that discontinuation would have little impact on bone composition. Modest differences were observed in three parameters that are not likely to affect bone mechanical properties. These preliminary data suggest that a 5-year BP holiday is not harmful to bone composition.

Optimizing Sequential and Combined Anabolic and Antiresorptive Osteoporosis Therapy

As osteoporosis therapy options have expanded, and clinical guidelines have begun to embrace the concept of limited treatment courses and “drug holidays,” the choices that physicians must make when initiating, electing to continue, or switching therapies have become more complex. As a result, one of the fundamental issues that must be carefully considered is whether, when, and in what sequence anabolic therapies should be utilized. This review evaluates the current evidence supporting the optimal sequence for the use of anabolic and antiresorptive drugs and assesses the expanding number of clinical trials favoring the initial use of anabolic therapy followed by an antiresorptive agent. This review also explores the evidence suggesting that the effectiveness of anabolic medications are diminished when used in patients that have been previously treated with specific antiresorptive drugs for prolonged periods. Finally, the recent advances in designing combination antiresorptive/anabolic treatment approaches are detailed, with a focus on combined denosumab/teriparatide regimens, which appear to provide the most substantial and clinically relevant skeletal benefits to patients with established osteoporosis. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

CT imaging features of antiresorptive agent-related osteonecrosis of the jaw/medication-related osteonecrosis of the jaw

OBJECTIVES

Antiresorptive agent-related osteonecrosis of the jaw (ARONJ)/medication-related osteonecrosis of the jaw (MRONJ) include both bisphosphonate-related osteonecrosis of jaw (BRONJ) and denosumab-related osteonecrosis of jaw (DRONJ). The purpose of this study is to study radiological characteristics of ARONJ/MRONJ. These imaging features may serve as one useful aid for assessing ARONJ/MRONJ.

METHODS

CT scans of 74 Japanese patients, who were clinically diagnosed by inclusion criteria of ARONJ/MRONJ, obtained between April 1, 2011 and September 30, 2016, were evaluated. We investigated the CT imaging features of ARONJ/MRONJ, and clarified radiological differentiation between BRONJ and DRONJ, BRONJ due to oral bisphosphonate administration and due to intravenous bisphosphonate administration, BRONJ with respective kinds of medication, BRONJ with long-term administration and short-term administration, BRONJ with each clinical staging respectively. Fisher's exact test, χ² test, Student's t-test and analysis of variance were performed in the statistical analyses.

RESULTS

Unilateral maxillary sinusitis was detected in all patients with upper ARONJ/MRONJ (100%). DRONJ showed large sequestrum more frequently than BRONJ (3/4, 75 vs 3/35, 8.6%, p < 0.05). DRONJ showed periosteal reaction more frequently than BRONJ (4/10, 40 vs 7/65, 10.1%, p < 0.05). Patients of BRONJ resulting from intravenous bisphosphonate administration showed larger and more frequent buccolingual cortical bone perforations than BRONJ resulting from oral bisphosphonate administration (7/8, 87.5 vs 11/30, 36.7%, p < 0.05). There was no significant correlation between CT findings and respective kinds of medication, long/short-term administration, clinical stages of BRONJ.

CONCLUSIONS

ARONJ/MRONJ has characteristic CT image findings which could be useful for its assessment.

Calcium Phosphates as Delivery Systems for Bisphosphonates

Bisphosphonates (BPs) are the most utilized drugs for the treatment of osteoporosis, and are usefully employed also for other pathologies characterized by abnormally high bone resorption, including bone metastases. Due to the great affinity of these drugs for calcium ions, calcium phosphates are ideal delivery systems for local administration of BPs to bone, which is aimed to avoid/limit the undesirable side effects of their prolonged systemic use. Direct synthesis in aqueous medium and chemisorptions from solution are the two main routes proposed to synthesize BP functionalized calcium phosphates. The present review overviews the information acquired through the studies on the interaction between bisphosphonate molecules and calcium phosphates. Moreover, particular attention is addressed to some important recent achievements on the applications of BP functionalized calcium phosphates as biomaterials for bone substitution/repair.

Hybrid Au@alendronate nanoparticles as dual chemo-photothermal agent for combined cancer treatment

A gold therapeutic nanoplatform with the same molecule used as reductant, coating and therapeutic agent has been developed in a one-pot, one-phase process using alendronate, a drug from the bisphosphonate family known for its antitumor effects. In addition, the core made of gold nanoparticles (NPs) brings thermal functionalities under irradiation within the first biological window (650-900 nm). The Au@alendronate nanoplatform thus provided a combined antitumor activity through drug delivery and photothermal therapy. Au@alendronate NPs inhibited in vitro the proliferation of prostate cancer cells (PC3) in a dose-dependent manner, with an IC₅₀ value of 100 µM. Under NIR irradiation a temperature increase was observed leading to a reduction of the IC₅₀ value to 1 µM, with total tumor cell death at 100 µM.

Sequential Delivery of Doxorubicin and Zoledronic Acid to Breast Cancer Cells by CB[7]-Modified Iron Oxide Nanoparticles

Drug-loaded magnetic nanoparticles were synthesized and used for the sequential delivery of the antiresorptive agent zoledronic acid (Zol) and the cytotoxic drug doxorubicin (Dox) to breast cancer cells (MCF-7). Zol was attached to bare iron oxide nanoparticles (IONPs) via phosphonate coordination to form Z-NPs. The unbound imidazole of Zol was then used to complex the organic macrocycle CB[7] to obtain CZ-NPs. Dox was complexed to the CZ-NPs to form the fully loaded particles (DCZ-NPs), which were stable in solution at 37 °C and physiological pH (7.4). Fluorescence spectroscopy established that Dox is released in solution from DCZ-NPs suddenly (i) when the particles are subjected to magnetically induced heating to 42 °C at low pH (5.0) and (ii) in the presence of glutathione (GSH). Mass spectrometry indicated that Zol is released slowly in solution at low pH after Dox release. Magnetic measurements with a magnetic reader revealed that DCZ-NPs are internalized preferentially by MCF-7 cells versus nonmalignant cells (HEK293). Zol and Dox acted synergistically when delivered by the particles. DCZ-NPs caused a decrease in the viability of MCF-7 cells that was greater than the net decrease caused when the drugs were added to the cells individually at concentrations equivalent to those delivered by the particles. MCF-7 cells were treated with DCZ-NPs and subjected to an alternating magnetic field (AMF) which, with the nanoparticles present, raised the temperature of the cells and triggered the intracellular release of Dox, as indicated by fluorescence activated cell sorting (FACS). The cytotoxic effects of the DCZ-NPs on MCF-7 cells were enhanced 10-fold by AMF-induced heating. DCZ-NPs were also able to completely inhibit MCF-7 cell adhesion and invasion in vitro, indicating the potential of the particles to act as antimetastatic agents. Together these results demonstrate that DCZ-NPs warrant development as a system for combined chemo- and thermo-therapeutic treatment of cancer.

Drug delivery systems functionalized with bone mineral seeking agents for bone targeted therapeutics

The systemic administration of drugs to treat bone diseases is often associated with poor uptake of the drug in the targeted tissue, potential systemic toxicity and suboptimal efficacy. In order to overcome these limitations, many micro- and nano-sized drug carriers have been developed for the treatment of bone pathologies that exhibit specific affinity for bone. Drug carriers can be functionalized with bone mineral seekers (BMS), creating a targeted drug delivery system (DDS) which is able to bind to bone and release therapeutics directly at the site of interest. This class of advanced DDS is of tremendous interest due to their strong affinity to bone, with great expectation to treat life-threatening bone disorders such as osteomyelitis, osteosarcoma or even osteoporosis. In this review, we first explain the mechanisms behind the affinity of several well-known BMS to bone, and then we present several effective approaches allowing the incorporation BMS into advanced DDS. Finally, we report the therapeutic applications of BMS based DDS under development or already established. Understanding the mechanisms behind the biological activity of recently developed BMS and their integration into advanced therapeutic delivery systems are essential prerequisites for further development of bone-targeting therapies with optimal efficacy.

Safety, pharmacokinetics, and changes in bone metabolism associated with zoledronic acid treatment in Japanese patients with primary osteoporosis

Although once-yearly intravenous administration of zoledronic acid has been reported to inhibit bone resorption and increase bone mineral density, no studies have evaluated its effectiveness in treating osteoporosis in Japanese patients. Therefore, the purpose of this study was to investigate the pharmacokinetics and assess the safety of and changes in bone metabolism associated with zoledronic acid treatment in Japanese patients with primary osteoporosis. This was a single-administration study with a single-blind parallel-group design. The study participants were 24 Japanese patients with primary osteoporosis. The patients were divided into two groups, with each group receiving a single injection of zoledronic acid (4 or 5 mg). Pharmacokinetics and urinary excretion were then compared, and drug-related adverse events and changes in the levels of bone turnover markers were assessed at 12 months. Mean plasma concentrations of zoledronic acid peaked in both groups immediately after administration, and decreased to 1% or less of peak levels after 24 h. Noncompartmental analysis revealed that C _max and the area under the curve from time zero to infinity increased in proportion to the dose. The levels of bone resorption and formation markers decreased from day 15 and from 3 months after administration respectively, and suppression of these markers remained constant for the entire study period. No serious adverse events were reported. There was no large difference between the 4- and 5-mg groups in terms of pharmacokinetics, changes in the levels of bone turnover markers, and safety profiles. This study demonstrated acceptable pharmacokinetics and changes in bone metabolism associated with zoledronic acid treatment in female Japanese osteoporosis patients. Both the 4-mg dose and the 5-mg dose demonstrated acceptable safety and sustained antiresorptive effects for the duration of the study.

Zoledronic acid in pediatric metabolic bone disorders

Zoledronic acid (ZA), a highly potent intravenous bisphosphonate (BP), has been increasingly used in children with primary and secondary osteoporosis due to its convenience of shorter infusion time and less frequent dosing compared to pamidronate. Many studies have also demonstrated beneficial effects of ZA in other conditions such as hypercalcemia of malignancy, fibrous dysplasia (FD), chemotherapy-related osteonecrosis (ON) and metastatic bone disease. This review summarizes pharmacologic properties, mechanism of action, dosing regimen, and therapeutic outcomes of ZA in a variety of metabolic bone disorders in children. Several potential novel uses of ZA are also discussed. Safety concerns and adverse effects are also highlighted.

Vitamin D (25-OHD) deficiency may increase the prevalence of medication-related osteonecrosis of the jaw

INTRODUCTION

Osteonecrosis of the jaw (ONJ) is a severe complication of antiresorptive medication (AM) in the treatment of bone-affecting cancer-related conditions and osteoporosis. Aim of this study was to reveal whether patients treated with AM and show Medication Related OsteoNecrosis of the Jaw (MRONJ) are vitamin D deficient or not.

MATERIALS AND METHODS

A 2 year retrospective study evaluated hospital records of 63 patients who received AM. Patients were divided into two groups. One group (n = 45) consisted of patients who presented a stage 2 ONJ (eb+ = exposed bone). Second group patients (n = 18) (eb- = no exposed bone) presented for extraction of teeth. Serum levels of vitamin D (25-OHD) were analysed. P values ≤ 0.05 in t-test were regarded as statistically significant.

RESULTS

Serum levels of 25-OHD were significantly higher in the eb(-) group (29.5 ng/ml), than in the eb(+) group (20.49 ng/ml). Blood levels of calcium were also significantly higher in eb(-) group (2.25 mmol/L; 0.11 SD) than in eb(+) group (2.175 mmol/L; 0.16 SD).

CONCLUSION

Prevalence of MRONJ in AM treated patients seems to be increased by low serum 25-OHD. A measurable tendency in the role of 25-OHD for the development of MRONJ was recorded and leads to the recommendation for a sufficient vitamin D substitution in patients treated with AM.

Treatment of OPG-deficient mice with WP9QY, a RANKL-binding peptide, recovers alveolar bone loss by suppressing osteoclastogenesis and enhancing osteoblastogenesis

Osteoblasts express two key molecules for osteoclast differentiation, receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG), a soluble decoy receptor for RANKL. RANKL induces osteoclastogenesis, while OPG inhibits it by blocking the binding of RANKL to RANK, a cellular receptor of RANKL. OPG-deficient (OPG^–/–) mice exhibit severe alveolar bone loss with enhanced bone resorption. WP9QY (W9) peptide binds to RANKL and blocks RANKL-induced osteoclastogenesis. W9 is also reported to stimulate bone formation in vivo. Here, we show that treatment with W9 restores alveolar bone loss in OPG^–/–mice by suppressing osteoclastogenesis and enhancing osteoblastogenesis. Administration of W9 or risedronate, a bisphosphonate, to OPG^–/–mice significantly decreased the osteoclast number in the alveolar bone. Interestingly, treatment with W9, but not risedronate, enhanced Wnt/β-catenin signaling and induced alveolar bone formation in OPG^–/–mice. Expression of sclerostin, an inhibitor of Wnt/β-catenin signaling, was significantly lower in tibiae of OPG^–/–mice than in wild-type mice. Treatment with risedronate recovered sclerostin expression in OPG^–/–mice, while W9 treatment further suppressed sclerostin expression. Histomorphometric analysis confirmed that bone formation-related parameters in OPG^–/–mice, such as osteoblast number, osteoblast surface and osteoid surface, were increased by W9 administration but not by risedronate administration. These results suggest that treatment of OPG^–/–mice with W9 suppressed osteoclastogenesis by inhibiting RANKL signaling and enhanced osteoblastogenesis by attenuating sclerostin expression in the alveolar bone. Taken together, W9 may be a useful drug to prevent alveolar bone loss in periodontitis.

Quercetin and alendronate multi-functionalized materials as tools to hinder oxidative stress damage

In spite of its remarkable anti-oxidant, anti-inflammatory, anti-cancer properties and its possible inhibition activity towards bone resorption, quercetin therapeutic use is limited by its poor bioavailability. Herein we developed a new multifunctionalized system for the local administration of quercetin and alendronate, one of the most potent anti-osteoporotic drugs, with the aim to get a material with enhanced properties. To this purpose we loaded quercetin on hydroxyapatite functionalized with alendronate, as well as on hydroxyapatite. Characterization was performed by means of X-ray diffraction, FT-IR and Raman spectroscopies, thermogravimetric and spectrophotometric analyses. Loading of quercetin from hydro-alcoholic solution increased with time and reached a constant value of about 5 weight% on both substrates, without causing significant structural and morphological modifications. Quercetin functionalized materials exhibit relevant anti-oxidant properties, in agreement with their high radical scavenging activity, and a quercetin sustained release in phosphate buffer. In vitro osteoblast and osteoclast co-culture in a microenvironment altered by oxidative stress shows that both alendronate and quercetin significantly reduce osteoclast viability, whereas they are able to counteract the negative effect of oxidative stress on osteoblast viability and differentiation, suggesting that their relative amount in the functionalized materials can be utilized to tailor bone cells response. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3293-3303, 2017.

Continued Treatment Effect of Zoledronic Acid Dosing Every 12 vs 4 Weeks in Women With Breast Cancer Metastatic to Bone: The OPTIMIZE-2 Randomized Clinical Trial

Importance

Zoledronic acid, a potent bisphosphonate, is commonly administered to patients with bone metastases to reduce the risk of skeletal-related events (SREs). However, there have been concerns regarding its long-term monthly administration.

Objective

To examine whether zoledronic acid every 12 weeks was noninferior to zoledronic acid every 4 weeks in patients with metastatic breast cancer that involved the bone who had previously received a standard dosing regimen of zoledronic acid and/or pamidronate disodium.

Design, Setting, and Participants

OPTIMIZE-2 was a prospective, randomized, double-blind, multicenter phase 3 trial of intention-to-treat (full analysis set), evaluable (per protocol), and safety populations. Patients were randomized (1:1) to receive 4.0 mg of intravenous zoledronic acid every 4 or every 12 weeks with placebo for interim infusions for 1 year. The study was conducted at 102 clinical trial centers in the United States from March 3, 2006, to July 25, 2013. Data analysis was performed from October 7, 2013, to March 24, 2014. The study randomized 416 women (≥18 years old) with bone metastases from breast cancer who previously received 9 or more doses of zoledronic acid and/or pamidronate during the first 10 to 15 months of therapy.

Main Outcomes and Measures

The primary end point was the proportion of patients with 1 or more SRE on study (SRE rate). The key secondary end points included time to first SRE and skeletal morbidity rate (SMR).

Results

A total of 416 women were randomized: 200 patients received zoledronic acid every 4 weeks (mean [SD] age, 59.2 [11.1] years; 173 were white [86.5%]), 203 patients received zoledronic acid every 12 weeks (mean [SD] age, 58.6 [11.2] years; 178 were white [87.7%]), and 13 patients received placebo (mean [SD] age, 60.8 [12.2] years; 13 were white [100%]). Baseline characteristics were similar in both zoledronic acid treatment arms. After 1 year of follow-up, SREs occurred in 44 patients (22.0%) in the zoledronic acid every 4 weeks group and 47 patients (23.2%) in the zoledronic acid every 12 weeks group (proportional difference of -1.2%; 1-sided 97.5% CI bound of the difference in SRE rate between arms, -9.8%; noninferiority P = .02). The time to first SRE between treatment groups was not statistically significantly different (hazard ratio [HR], 1.06; 95% CI, 0.70-1.60; P = .79). The mean (SD) SMR was 0.46 (1.06) vs 0.50 (1.50) events per year in the every 4 weeks vs every 12 weeks groups (P = .85). The safety profiles of the every 4 weeks and every 12 weeks groups were comparable, with 189 patients (95.5%) in the every 4 weeks group having at least 1 adverse event compared with 189 (93.5%) in the every 12 weeks group.

Conclusions and Relevance

The every 12 weeks regimen of zoledronic acid was noninferior to the every 4 weeks regimen for the proportion of patients experiencing 1 or more SRE. These results may have a substantial influence on current clinical practice for treatment of patients with bone metastasis from breast cancer.

Trial Registration

clinicaltrials.gov Identifier: NCT00320710.

Surgical trauma and low-dose methylprednisolone modulate the severity of the acute-phase response induced by zoledronic acid infusion

The aim of the present study was to investigate risk factors for the development of an acute-phase response (APR) associated with the initial zoledronic acid (ZA) infusion in patients undergoing surgery, and to assess whether its onset may be reduced by post-dose administration of low-dose methylprednisolone (MP) or acetaminophen. A retrospective study of patients with osteoporosis who attended the departments of orthopedics and endocrinology of a single hospital and received 5 mg ZA was conducted; the patients included surgical and non-surgical cases. A total of 450 ZA-naïve patients who were treated with acetaminophen following ZA infusion were stratified based on whether they suffered APR (APR⁺) or not (APR^-). In addition, 155 of the aforementioned acetaminophen-treated patients (acetaminophen group) were compared with another 32 patients from the orthopedic department who were treated with MP immediately following ZA infusion (MP group). Inflammatory marker levels were significantly higher in APR⁺ patients than in APR^- patients, and the odds ratios of experiencing APR following minimally invasive or open surgery were found to be 3.54 (P<0.001) and 5.71 (P<0.001), respectively, compared with non-surgical intervention after multiple adjustments. C-reactive protein levels prior to dosing were positively correlated with body temperature (r=0.023; P<0.001). The severity of APR also exhibited a negative correlation with 23-hydroxyvitamin D3 levels (r=-0.006; P<0.05). Patients treated with MP following surgery and ZA infusion had a significantly lower incidence of APR compared with those treated with acetaminophen (6.3 vs. 62.6%; P<0.05). However, no significant differences were observed in bone mineral density between the MP and acetaminophen groups at 12 months post-surgery. The results of the present study suggest that surgical trauma serves a key role in ZA-associated APR, and low-dose MP may a suitable post-dose treatment to manage the symptoms of APR in patients undergoing surgery.

Bisphosphonate-Functionalized Hydroxyapatite Nanoparticles for the Delivery of the Bromodomain Inhibitor JQ1 in the Treatment of Osteosarcoma

Osteosarcoma (OS) is one of the most common neoplasia among children, and its survival statistics have been stagnating since the combinatorial anticancer therapy triad was first introduced. Here, we report on the assessment of the effect of hydroxyapatite (HAp) nanoparticles loaded with medronate, the simplest bisphosphonate, as a bone-targeting agent and JQ1, a small-molecule bromodomain inhibitor, as a chemotherapeutic in different 2D and 3D K7M2 OS in vitro models. Both additives decreased the crystallinity of HAp, but the effect was more intense for medronate because of its higher affinity for HAp. As the result of PO₄^3--NH⁺ binding, JQ1 shielded the surface phosphates of HAp and pushed its surface charge to more positive values, exhibiting the opposite effect from calcium-blocking medronate. In contrast to the faster and more exponential release of JQ1 from monetite, its release from HAp nanoparticles followed a zero-order kinetics, but 98% of the payload was released after 48 h. The apoptotic effect of HAp nanoparticles loaded with JQ1, with medronate and with both JQ1 and medronate, was selective in 2D culture: pronounced against the OS cells and nonexistent against the healthy fibroblasts. While OS cell invasion was significantly inhibited by all of the JQ1-containing HAp formulations, that is, with and without medronate, all of the combinations of the targeting compound, medronate, and the chemotherapeutic, JQ1, delivered using HAp, but not HAp alone, inhibited OS cell migration from the tumor spheroids. JQ1 delivered using HAp had an effect on tumor migration, invasion, and apoptosis even at extremely low, subnanomolar concentrations, at which no effect of JQ1 per se was observed, meaning that this form of delivery could help achieve a multifold increase of this drug's efficacy. More than 80% of OS cells internalized JQ1-loaded HAp nanoparticles after 24 h of coincubation, suggesting that this augmentation of the activity of JQ1 may be due to the intracellular delivery and sustained release of the drug enabled by HAp. In addition to the reduction of the OS cell viability, the reduction of the migration and invasion radii was observed in OS tumor spheroids challenged with even JQ1-free medronate-functionalized HAp nanoparticles, demonstrating a definite anticancer activity of medronate alone when combined with HAp. The effect of medronate-functionalized JQ1-loaded HAp nanoparticles was most noticeable against OS cells differentiated into an osteoblastic lineage, in which case they surpassed in effect pure JQ1 and medronate-free compositions. The activity of JQ1 was mediated through increased Ezrin expression and decreased RUNX2 expression and was MYC and FOSL1 independent, but these patterns of gene expression changed in cells challenged with the nanoparticulate form of delivery, having been accompanied by the upregulation of RUNX2 and downregulation of Ezrin in OS cells treated with medronate-functionalized JQ1-loaded HAp nanoparticles.

A novel fluorescent probe-based flow cytometric assay for mineral-containing nanoparticles in serum

Calciprotein particles, nanoscale aggregates of insoluble mineral and binding proteins, have emerged as potential mediators of phosphate toxicity in patients with Chronic Kidney Disease. Although existing immunochemical methods for their detection have provided compelling data, these approaches are indirect, lack specificity and are subject to a number of other technical and theoretical shortcomings. Here we have developed a rapid homogeneous fluorescent probe-based flow cytometric method for the detection and quantitation of individual mineral-containing nanoparticles in human and animal serum. This method allows the discrimination of membrane-bound from membrane-free particles and different mineral phases (amorphous vs. crystalline). Critically, the method has been optimised for use on a conventional instrument, without the need for manual hardware adjustments. Using this method, we demonstrate a consistency in findings across studies of Chronic Kidney Disease patients and commonly used uraemic animal models. These studies demonstrate that renal dysfunction is associated with the ripening of calciprotein particles to the crystalline state and reveal bone metabolism and dietary mineral as important modulators of circulating levels. Flow cytometric analysis of calciprotein particles may enhance our understanding of mineral handling in kidney disease and provide a novel indicator of therapeutic efficacy for interventions targeting Chronic Kidney Disease-Mineral Bone Disorder.

Smart, programmable and responsive injectable hydrogels for controlled release of cargo osteoporosis drugs

Easy-to-prepare drug delivery systems, based on smart, silica gels have been synthesized, characterized, and studied as hosts in the controlled release of bisphosphonates. They exhibit variable release rates and final % release, depending on the nature of bisphosphonate (side-chain length, hydro-philicity/-phobicity, water-solubility), cations present, pH and temperature. These gels are robust, injectable, re-loadable and re-usable.

Effect of Sequential Treatment with Bisphosphonates After Teriparatide in Ovariectomized Rats: A Direct Comparison Between Risedronate and Alendronate

Teriparatide (TPTD), a recombinant human parathyroid hormone N-terminal fragment (1-34), is a widely used bone anabolic drug for osteoporosis. Sequential treatment with antiresorptives such as bisphosphonates after TPTD discontinuation is generally recommended. However, relative effects of bisphosphonates have not been determined. In the present study, we directly compared effects of risedronate (RIS) and alendronate (ALN) on bone mineral density (BMD), bone turnover, structural property and strength in ovariectomized (OVX) rats, when administered after TPTD. Female Sprague Dawley rats were divided into one sham-operated and eight ovariectomized groups. TPTD, RIS, and ALN were given subcutaneously twice per week for 4 or 8 weeks after 4 week treatment with TPTD. TPTD significantly increased BMD (+9.6%) in OVX rats after 4 weeks of treatment. 8 weeks after TPTD withdrawal, vehicle-treated group showed a blunted BMD increase of +8.4% from the baseline. In contrast, 8 weeks of treatment with RIS and ALN significantly increased BMD to 17.4 and 21.8%, respectively. While ALN caused a consistently larger increase in BMD, sequential treatment with RIS resulted in lower Tb.Sp compared to ALN in the fourth lumbar vertebra as well as in greater stiffness in compression test. In conclusion, the present study demonstrated that sequential therapy with ALN and RIS after TPTD both improved bone mass and structure. Our results further suggest that RIS may have a greater effect on improving bone quality and stiffness than ALN despite less prominent effect on BMD. Further studies are necessary to determine clinical relevance of these findings to fracture rate.

Long-Term Bone Scintigraphy Results After Intravenous Zoledronate in Paget's Disease of Bone

Zoledronate produces long-term normalization of biochemical markers in Paget's disease but whether this implies the absence of active disease is unknown. We have determined whether bone scintigraphy, a more sensitive index of disease activity, is also normalized ≥5 years after treatment with zoledronate. A consecutive case series of 11 individuals with Paget's disease treated with zoledronate 5 mg ≥5 years previously is reported. Eight patients received a single zoledronate infusion and were assessed 55-120 months later. Bone scintigraphy showed no evidence of active disease in four of these patients, and there was minimal residual disease activity in the other four. Three other patients required second infusions because of evidence of ongoing disease activity. In two of these, scintigraphy was normal ~90 months after their second infusions. In the third, further follow-up is not available. Procollagen-I N-terminal propeptide and total alkaline phosphatase were normal in all subjects at the time of bone scintigraphy. This case series confirms the high rate of response of Paget's disease to zoledronate, demonstrates the much greater sensitivity of scintigraphy compared with biochemical markers in detecting ongoing disease activity, and indicates that about one-third may be scintigraphically "cured" after one infusion; one-third have scintigraphically trivial disease activity subsequently, and the balance may require a second infusion. Scintigraphic "cure" is achievable after second infusions. Scintigraphy has an important place in the long-term management of Paget's patients following zoledronate, and should guide follow-up decisions in those with normal biochemical markers.

High-scale yield of nano hydroxyapatite through combination of mechanical activation and chemical dispersion

The aim of this study is to develop a simple, convenient and effective approach to synthesize nano-sized hydroxyapatite (nano-HA) at high-scale yield. Nano-HA was wet synthesized in the presence or absence of alendronate sodium (ALN), one of bisphosphonates for anti-osteoporotic. Then aged and washed nano-HA precipitate was directly treated by mechanical activation combined with the chemical dispersion of ALN to prevent the agglomeration of nano-HA. ALN acted not only as a chemical dispersant but also as an orthopedic drug. In vitro release showed that ALN was released slowly from nano-HA. Transmission electron microscopy (TEM) revealed that nano-HA with size less than 100 nm appeared as single particle after being treated by mechanical activation combined with the dispersion of ALN (AMA-HA and MA-HA). High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) confirmed that as-prepared nanoparticles were HA with low crystallinity and crystallite size. Fourier transform infrared spectroscopy (FTIR) indicated that the phosphonate groups in ALN were introduced to bond with the Ca²⁺ of HA to impede the growth of HA crystal. Zeta potential illustrated that the absolute value of surface negative charge of nano-HA increased significantly with the addition of ALN, which inhibited the agglomeration of nano-HA. The present approach makes it feasible to produce nano-HA at high-scale yield, which provide the possibility to construct bone graft.

Poly(vinyl alcohol)/hydroxyapatite Monolithic In-Needle Extraction (MINE) device: Preparation and examination of drug affinity

Polymer-ceramic materials based on poly(vinyl alcohol) (PVA) and hydroxyapatite were applied as sorption material in Monolithic In-Needle Extraction (MINE) device. The presented device provides new possibilities for the examination of bisphosphonates affinity for bone and will be a helpful tool in evaluation of potential antiresorptive drugs suitability. A ceramic part of monoliths was prepared by incorporation of hydroxyapatite (HA) into the reaction mixture or by using a soaking method (mineralization of HA on the PVA). The parameters of synthesis conditions were optimized to achieve a monolithic material having the appropriate dimensions after the soaking process enabling placing of the monolithic material inside the needle. Furthermore, the material must have had optimal dimensions after the re-soaking process to fit perfectly to the needle. Among the sixteen monolithic materials, eight of them were selected for further study, and then four of them were selected as a sorbent material for the MINE device. The material properties were examined on the basis of several parameters: swelling ratio, initial mass reversion and initial diameter reversion, mass growth due to the HA formation, and antiresorptive drug sorption. The MINE device might be then used as a tool for examination of interactions between bisphosphonate and bone. The simulated body fluid containing sodium risedronate (RSD) as a standard compound was passed through the MINE device. The obtained device allowed for sorption about 0.38mg of RSD. The desorption process was carried out in five steps allowing insightful analysis. The MINE device turned out to be a helpful tool for determination of the bisphosphonates affinity to the ceramic part of sorbent (hydroxyapatite) and to assess the usefulness of them as antiresorptive drugs in the future.

Importance of prompt antiresorptive therapy in postmenopausal women discontinuing teriparatide or denosumab: The Denosumab and Teriparatide Follow-up study (DATA-Follow-up)

When teriparatide and denosumab are discontinued, bone mineral density (BMD) abruptly decreases. To compare rates of bone loss in postmenopausal women who discontinue denosumab or teriparatide and receive no additional prescription osteoporosis medications to women who discontinue these drugs followed by prompt antiresorptive therapy, we asked women concluding the Denosumab and Teriparatide Administration (DATA) study and its extension, DATA-Switch, to return for BMD measurements 1-2years after study completion. In these studies, women received 2-years of either teriparatide, denosumab or both medications followed by 2-years of the alternate therapy (women who received combination therapy initially received an additional 2-years of denosumab alone). Fifty of 69 women who completed DATA-Switch returned after a mean of 15.4±3.5months. Of the 28 women who received antiresorptive therapy (10 denosumab, 10 oral bisphosphonates, 8 intravenous zoledronic acid), the mean interval between ending DATA-Switch and beginning antiresorptive therapy was 3.8±3.1months. In the 22 women not receiving follow-up therapy, femoral neck, total hip, and spine BMD decreased by -4.2±4.3%, -4.5±3.6%, and -10.0±5.4%, respectively, while BMD was maintained in those who did receive follow-up antiresorptive drugs (femoral neck, total hip, and spine BMD changes of -0.6±2.7%, -0.8±3.1%, and -1.2±4.7%, respectively, P<0.001 for all between-group comparisons). Among untreated women, femoral neck BMD decreased more in those discontinuing denosumab (-5.8±4.0%) than in those discontinuing teriparatide (-0.8±2.6%, P=0.008). Total hip BMD, but not spine BMD, showed a similar pattern. Among treated women, denosumab increased femoral neck and total hip BMD more than bisphosphonates while BMD changes at the spine did not differ significantly. In summary, the large teriparatide and denosumab-induced gains in BMD achieved with 4years of intensive therapy in the DATA and DATA-Switch studies were maintained in patients who received prompt antiresorptive therapy but not in those left untreated. These results demonstrate the negative consequences of delaying consolidation therapy in women treated with these drugs and underscore the importance of timely medication transitions in such patients.

Antiresorptive and anti-angiogenetic octacalcium phosphate functionalized with bisphosphonates: An in vitro tri-culture study

Development of new materials for the local administration of bisphosphonates (BPs) is aimed to avoid the negative side effects of prolonged systemic use of these potent drugs. In this work, we synthesized octacalcium phosphate (OCP) in the presence of two potent BPs and obtained a single crystalline phase up to a zoledronate and alendronate content of 3.5wt% and 5.2wt%, respectively. Both BPs provoke minor structural modifications and a reduction of the crystal dimensions of OCP, which suggests a preferential interaction of the BPs with the structure of the calcium phosphate. Alendronate containing samples display increased values of zeta potential with respect to that of OCP, and an initial burst release of the BP in solution. At variance, the zeta potential of zoledronate functionalized samples decreases on increasing the content of zoledronate, which is not appreciably released in solution. Bone microenvironment response to the composite materials was investigated in vitro using a triculture model. BP functionalized samples downregulate the viability of the cells, sustain osteoblast differentiation and accelerate the production of collagen type I and osteocalcin. At variance, they inhibit monocyte differentiation into osteoclast and provoke a dose dependent reduction of VEGF production, exhibiting antiresorptive and anti-angiogenetic properties that can be usefully exploited for the local treatment of abnormal bone losses.

STATEMENT OF SIGNIFICANCE

Bisphosphonates (BPs) are powerful drugs for the treatment of bone diseases. However, BPs systemic administration suffers several undesirable side effects, which stimulate the development of suitable systems for their local administration. In this study we functionalized octacalcium phosphate (OCP) with alendronate and zoledronate in order to get biomaterials able to couple the good biological performance of OCP with the therapeutic properties of the BPs. The results provide novel information on the interaction between these two potent BPs and octacalcium phosphate. Moreover, the triculture in vitro study indicates that the synthesized composite materials stimulate the production of bone extracellular matrix, inhibit monocytes differentiation into osteoclasts and downregulate the release of Vascular Endothelial Growth Factor (VEGF) in a dose dependent way. The data allow to state that the new composite materials can be usefully employed for the local treatment of diseases involving abnormally high bone resorption.

Parathyroid Hormone and Parathyroid Hormone-Related Protein Analogs in Osteoporosis Therapy

PURPOSE OF REVIEW

The purpose is to review the efficacy and optimal use of parathyroid hormone and parathyroid hormone-related protein analogs in osteoporosis treatment.

RECENT FINDINGS

The parathyroid hormone analog teriparatide, a potent stimulator of bone remodeling, increases hip and spine bone mineral density and reduces the risk of vertebral and non-vertebral fractures in postmenopausal osteoporotic women. The parathyroid hormone-related protein analog, abaloparatide, also reduces fracture incidence but has pharmacological effects that differ from teriparatide, particularly in cortical bone. These analogs provide maximal benefit when their use is followed by a potent antiresorptive medication. Moreover, studies have shown that the combination of teriparatide and the RANK-ligand inhibitor, denosumab, increase bone density and estimated strength more than monotherapy and more than any currently available regimen. Parathyroid hormone and parathyroid hormone-related protein analogs, whether as monotherapy, in combination with antiresorptive agents or in sequence with antiresorptive agents, will likely play an expanding role in osteoporosis management.

Local Administration of Bisphosphonate-soaked Hydroxyapatite for the Treatment of Osteonecrosis of the Femoral Head in Rabbit

Background:

Systemic administration of bisphosphonates has shown promising results in the treatment of osteonecrosis of the femoral head (ONFH). However, few studies have evaluated the efficacy of local zoledronate (ZOL) administration in the treatment of ONFH. The purpose of this study was to investigate whether local administration of bisphosphonate-soaked hydroxyapatite (HA) could improve bone healing in an experimental rabbit model of ONFH.

Methods:

This experimental study was conducted between October 2014 and June 2015. Forty-five rabbits underwent simulated ONFH surgery. Immediately following surgery, they were divided into three groups: model (untreated, n = 15), HA (treated with HA alone, n = 15), and HA + ZOL (treated with HA soaked in a low-dose ZOL solution, n = 15). Histological, immunohistochemical, and quantitative analyses were performed to evaluate bone formation and resorption 2, 4, and 8 weeks after surgery.

Results:

Gross bone matrix and hematopoietic tissue formation were observed in the HA + ZOL group 4 weeks after surgery. The immunohistochemical staining intensities for 5-bromodeoxyuridine, runt-related transcription factor 2, osteocalcin, osteopontin, and osteoprotegerin were significantly higher in the HA + ZOL group than that in the model (P < 0.001, P < 0.001, P < 0.001, P < 0.001, and P = 0.018, respectively) and HA groups (P = 0.003, P = 0.049, P < 0.001, P = 0.020, and P = 0.019, respectively), whereas receptor activator of the nuclear factor-κB ligand staining intensity was significantly lower in the HA + ZOL group than that in the model and HA groups (P = 0.029 and P = 0.015, respectively) 4 weeks after surgery. No significant differences in bone formation or bone resorption marker expression were found between the three groups 2 or 8 weeks after surgery (P > 0.05).

Conclusions:

Local administration of HA soaked in a low-dose ZOL solution increased new bone formation while inhibiting bone resorption in an animal model of ONFH, which might provide new evidence for joint-preserving surgery in the treatment of ONFH.

Preparation and evaluation of rhenium-188-pamidronate as a palliative treatment in bone metastasis

OBJECTIVE

Rhenium-188-hydroxyethylidene diphosphonate (¹⁸⁸Re-HEDP) as a first generation bisphosphonate has been widely used for bone seeking radiopharmaceutical in cases of metastatic bone disease. No study has been yet reported on preparing a complex of ¹⁸⁸Re with pamidronate (3-aminohydroxypropylidene-1,1-bisphosphonic acid) (PMA) as a second generation bisphosphonate. Based on this fact, it was hypothesized that a bone-seeking ¹⁸⁸Re-PMA radiopharmaceutical could be developed as an agent for palliative radiotherapy of bone pain due to skeletal metastases.

METHODS

Pamidronate was labeled with ¹⁸⁸ReO₄^- eluted from the alumina based ¹⁸⁸W/¹⁸⁸Re generator. Labeling was optimized, and radiochemical analysis was performed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Biodistribution of this radioconjugate was evaluated and verified further in mice.

RESULTS

¹⁸⁸Re-PMA was prepared successfully in a high labeling yield (˃95%) corresponding to a specific activity of 124MBq/μmol and good in vitro stability, but it is likely to consist of multiple species. In biodistribution studies selective uptake and retention of activity in the skeletal system (0.81±0.25% ID/g and 0.57±0.16 at 4 and 48h in bone post injection respectively) followed by clearance in the soft tissues were observed.

CONCLUSION

These results show that due to its biological capabilities it would be advantageous to use ¹⁸⁸Re-PMA for bone pain palliation therapy.

Long-Term Effects of Intravenous Ibandronate in Paget's Disease of Bone

We have previously demonstrated that intravenous ibandronate produces high initial response rates in Paget's disease, but the durability of this effect is unknown. It might be expected to be short lived because ibandronate has a low affinity for bone. Here we report long-term follow-up (up to 14 years) of patients from that trial. Twenty-five patients with active Paget's disease [baseline serum total alkaline phosphatase (ALP) ~3 times the upper limit of normal] received either 6 or 12 mg intravenous ibandronate at baseline. There were prompt reductions in ALP following treatment, with normalization in 88%. ALP remained in the normal range in most patients for 20-30 months, but some subjects then showed gradual increases. Three years after ibandronate, before any patients had received additional treatment, ALP was normal in 61%. Six patients maintained normal ALP beyond 6 years without further intervention. Responses to 6 and 12 mg were similar. These results indicate that long-term remissions in Paget's disease can be achieved with bolus delivery of a potent bisphosphonate, even if the drug has a low affinity for bone. Therefore, bisphosphonate retention in bone might not be the only factor determining duration of remission. Intravenous bisphosphonates are likely to produce high drug concentrations within pagetic lesions which might result in cytotoxicity to the pagetic cells, leading to long durations of remission. These findings strengthen the evidence that potent bisphosphonates delivered in a single intravenous dose are a very efficient way to manage this condition.