Renal safety of intravenous bisphosphonates in the treatment of osteoporosis

Osteoporosis and Fragility Fractures: currently available pharmacological options and future directions

Osteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. The average lifetime risk of a 50-year-old woman to suffer a fracture of the spine, hip, proximal humerus, or distal forearm has been estimated at close to 50%. In general, pharmacological treatment is recommended in patients who suffered a fragility fracture because their risk of suffering a subsequent fracture is increased dramatically. Therefore, many guidelines recommend pharmacological treatment in patients without a prevalent fracture if their fracture probability is comparable to or higher than that of a person of the same age with a prevalent fracture. The present review aims to highlight currently available pharmacological treatment options and their antifracture efficacy including safety aspects. Drug classes discussed comprise bisphosphonates, selective estrogen receptor modulators, parathyroid hormone peptides and derivatives, humanized monoclonal antibodies, and estrogens and gestagens and their combinations. Furthermore, a brief glimpse is provided into a potentially promising treatment option that involves mesenchymal stem cells.

Is the Use of Bisphosphonates Putting Horses at Risk? An Osteoclast Perspective

Simple Summary

Bisphosphonates are a group of drugs that intervene in the bone resorption process, producing cellular death of osteoclasts. These drugs are used for skeletal conditions, such as osteoporosis in humans, and are available for veterinary medical use. Clodronate and tiludronate are bisphosphonates approved for the treatment of navicular syndrome in horses over four years old. However, these drugs are sometimes used in juvenile animals under exercise, where osteoclast activity is higher. Bisphosphonate use in juvenile and/or exercising animals could have adverse effects, including maladaptation to exercise or accumulation of microdamage. Furthermore, bisphosphonates can be bound to the skeleton for several years, resulting in a prolonged effect with no pharmaceutical reversal available. This review presents an overview of osteoclast function and a review of bisphosphonate characteristics, mechanisms of action, and side effects in order to contextualize the potential for adverse/side effects in young or exercising animals.

Abstract

Osteoclasts are unique and vital bone cells involved in bone turnover. These cells are active throughout the individual’s life and play an intricate role in growth and remodeling. However, extra-label bisphosphonate use may impair osteoclast function, which could result in skeletal microdamage and impaired healing without commonly associated pain, affecting bone remodeling, fracture healing, and growth. These effects could be heightened when administered to growing and exercising animals. Bisphosphonates (BPs) are unevenly distributed in the skeleton; blood supply and bone turnover rate determine BPs uptake in bone. Currently, there is a critical gap in scientific knowledge surrounding the biological impacts of BP use in exercising animals under two years old. This may have significant welfare ramifications for growing and exercising equids. Therefore, future research should investigate the effects of these drugs on skeletally immature horses.

Comparison of the Effect of Oral Versus Intravenous Bisphosphonate Administration on Osteoclastogenesis in Advanced-Stage Medication-Related Osteonecrosis of the Jaw Patients

It is yet unknown whether the intravenous administration route alone can fully account for the exacerbation of medication-related osteonecrosis of the jaw (MRONJ). The purpose of this retrospective study was to identify the potential role of the bisphosphonate (BP) administration route as an independent prognostic factor for non-cancerous, stage III MRONJ patients. Bone samples were retrospectively obtained from two groups of osteoporosis patients who underwent surgery for the treatment of stage III MRONJ. Among the subjects, 10 had a history of only oral BP consumption and 10 of intravenous (IV) BP administration. The samples were assessed for osteoclast morphology and immunohistochemical expression of the receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), and potassium calcium-activated channel subfamily N member 4 (Kcnn4). Although the osteoclasts derived from both groups exhibited no significant differences in the mean quantity, diameter, and nuclearity, significantly attenuated tartrate-resistant acid phosphatase activity was noted among the IV BP-induced MRONJ bones compared to those of the oral BP group. Significant suppression of the RANKL/OPG ratio and Kcnn4 expression among the retrieved bones of IV BP group patients was also noted. Our results indicate the potential of the BP administration route as an independent prognostic factor for advanced-stage MRONJ, regardless of the dosage or indication for which the BP was prescribed.

The association between renal function and BMD response to bisphosphonate treatment: Real-world cohort study using linked national registers

BACKGROUND

Management of osteoporosis given reduced renal function is one of the largest challenges in the bone clinic.

OBJECTIVES

Identify the cut-off for renal function below which there would be no overall BMD benefit associated with bisphosphonate use. Track safety outcomes resulting in hospital encounters.

METHODS

Population-based, observational register-linked study of BMD trajectories in adults from the island of Funen (pop 465,000) as a function of estimated creatinine clearance (CKD-epi), treatment and adherence to oBP. One laboratory performed all the biochemical analyses for the area while all DXA scans were in a central facility. For inclusion, patients were required to have both a DXA scan and an eGFR measurement (CKD-EPI) within 1 year prior to their study index date. Medication Possession Ratio (MPR) was calculated from national data.

RESULTS

Out of 6176 incident BP users, 1789 had eGFR and DXA measurements at appropriate timepoints for the planned analysis, while this was the case for 3908 of 29,336 non-users. Users of oBPs exhibited progressively smaller gains in BMD with decreasing renal function. However, for CKD stage 3A and better, the annual change in BMD was significantly more positive than in the non-user group at similar levels of renal function. In non-users, the average annual change in BMD was negative but largely unaffected by renal function down to stage 3B. There were no new cases of acute renal injury, glomerulonephritis or dialysis. The rate of new kidney transplantation was zero in non-users and 0.26 per 1000 PY in the BP user population. Hypocalcaemia encounters did not differ significantly from that seen in non-users.

CONCLUSIONS

The BMD changes observed in real-world users of oBP in this population based single-clinic are consistent with those observed in the original RCTs of alendronate. We noted a gradual decrease in the absolute gains in BMD in oBP users with decreasing renal function though there was no significant interaction - largely explained by low numbers of treated patients with poor renal function - between CKD stage and adherence driven BMD change. There were no cases of acute renal injury resulting in hospital encounters. More data is needed on the efficacy and safety of bisphosphonates in CKD stage 3B to 5 and prescribers should reconsider the low use of DXA in patients with renal function impairment now that a wider range of treatment options are available.

Zoledronic acid induces micronuclei formation, mitochondrial-mediated apoptosis and cytostasis in kidney cells

AIMS

Zoledronic acid (ZA), a FDA approved drug has used widely in the treatment of bone metastasis complications, has been linked to renal toxicity with unclear mechanism. The present study is aimed at investigating the genotoxic and cytotoxic effects of ZA in renal epithelial cells.

MAIN METHODS

The genotoxic effect of ZA in Vero and MDCK cells determined by cytokinesis block micronucleus (CBMN) assay. The cytotoxic effect assessed by analysing cell cycle profile, cell death and mitochondrial membrane potential by flow cytometry using propidium iodide, AnnexinV-FITC/PI and JC1 dye staining, respectively, BAX and Bcl-2 expression by Western blotting and caspase activity by spectrofluorimetry.

KEY FINDINGS

The cytotoxic effect of ZA based on MTT assay revealed variable sensitivities of Vero and MDCK cells, with IC₅₀ values of 7.41 and 109.58 μM, respectively. The CBMN assay has shown prominent dose-dependent (IC_10-50) induction of micronuclei formation in both cells, indicating ZA's clastogenic and aneugenic potential. Further, the ZA treatment led the cells to apoptosis, evident from dose-dependent increase in the percentage of cells in subG1 phase and display of membranous phosphatidylserine translocation. Studies also confirmed apoptosis through mitochondria, evident from the prominent increase in BAX/Bcl-2 ratio, mitochondrial membrane depolarization and caspase-3/7 activity. In addition, ZA reduces cytokinetic activity of renal cells, evident from dose-wise lowered replicative indices.

SIGNIFICANCE

The study depict ZA's potential genotoxic effect along with cytotoxic effect in renal epithelial cells, could be key factors for the development of renal complications associated with it, which prompts renal safety measures in lieu with ZA usage.

Denosumab for treatment of immobilization-related hypercalcaemia in a patient with advanced renal failure

We describe the case of a young adult with immobilization-related hypercalcaemia and advanced renal insufficiency. Because of the uncertain safety profile of bisphosphonates in such patients, only a low dose of pamidronate was administered twice. This did not result in a sufficient decrease in the serum calcium concentration nor was the decrease sustained. We decided to administer a single dose of denosumab, a monoclonal antibody against the receptor activator of nuclear factor-κB ligand, a new antiresorptive agent registered for use in osteoporosis. This resulted in rapid and sustained decrease in the serum calcium concentration. Transient hypocalcaemia ensued with normalization after vitamin D supplementation. Furthermore, we summarize what is known about hypercalcaemia caused by immobilization.

Clinical role of bisphosphonate therapy

Bisphosphonates (BPs) are synthetic analogues of pyrophosphate. They inhibit bone resorption and are therefore widely used in disorders where there are increases or disruptions in bone resorption. This includes postmenopausal osteoporosis, glucocorticoid-induced osteoporosis, Paget's disease of bone, and malignancy-related bone loss. To best understand the clinical application of BPs, an understanding of their pharmacokinetics and pharmacodynamics is important. This review describes the structure, pharmacology and mode of action of BPs, focusing on their role in clinical practice. Controversies and side effects surrounding their use will also be discussed.

Bisphosphonates in the treatment of osteoporosis

Bisphosphonates are widely used in the treatment of osteoporosis to reduce fracture risk. Because of their long retention time in bone and uncommon side effects, questions have been raised about the optimal duration of therapy. Potential side effects appear to be rare and may not be causally related. Although there is no strong science to guide "drug holidays," there appears to be some lingering antifracture benefit when treatment is stopped, so some time off treatment should be offered to most patients on long-term bisphosphonate therapy. For most patients with osteoporosis, the benefits of treatment outweigh the risks.

Postmenopausal osteoporosis treatment with antiresorptives: effects of discontinuation or long-term continuation on bone turnover and fracture risk--a perspective

Osteoporosis may be a lifelong condition. Robust data regarding the efficacy and safety of both long-term osteoporosis therapy and therapy discontinuation are therefore important. A paucity of clinical trial data regarding the long-term antifracture efficacy of osteoporosis therapies necessitates the use of surrogate endpoints in discussions surrounding long-term use and/or discontinuation. Long-term treatment (beyond 3-4 years) may produce further increases in bone mineral density (BMD) or BMD stability, depending on the specific treatment and the skeletal site. Bisphosphonates, when discontinued, are associated with a prolonged reduction in bone turnover markers (BTMs), with a very gradual increase to pretreatment levels within 3 to 60 months of treatment cessation, depending on the bisphosphonate used and the prior duration of therapy. In contrast, with nonbisphosphonate antiresorptive agents, such as estrogen and denosumab, BTMs rebound to above pretreatment values within months of discontinuation. The pattern of BTM change is generally mirrored by a more or less rapid decrease in BMD. Although the prolonged effect of some bisphosphonates on BTMs and BMD may contribute to residual benefit on bone strength, it may also raise safety concerns. Adequately powered postdiscontinuation fracture studies and conclusive evidence on maintenance or loss of fracture benefit is lacking for bisphosphonates. Similarly, the effects of rapid reversal of bone turnover upon discontinuation of denosumab on fracture risk remain unknown. Ideally, studies evaluating the effects of long-term treatment and treatment discontinuation should be designed to provide head-to-head "offset" data between bisphosphonates and nonbisphosphonate antiresorptive agents. In the absence of this, a clinical recommendation for physicians may be to periodically assess the benefits/risks of continuation versus discontinuation versus alternative management strategies.

Effects of intravenous ibandronate injection on renal function in women with postmenopausal osteoporosis at high risk for renal disease--the DIVINE study

The Designed for intravenous (IV) Ibandronate reNal safety Evaluation (DIVINE) study was a 1-year prospective, randomized, open label, multi-center study that evaluated the renal safety of quarterly (every 3 months) ibandronate IV injection given over 15-30s compared with infusion given over 15 min, and weekly oral alendronate, in women with postmenopausal osteoporosis (PMO) at increased risk for renal disease. Both injection and infusion of IV ibandronate showed comparable safety to alendronate, with only small changes in serum creatinine (sCr) for each treatment group, and AEs were generally comparable between groups. All three treatments had similar effects on renal function, measured by change in baseline of the glomerular filtration rate; the ibandronate IV injection group was noninferior to the ibandronate IV infusion and weekly oral alendronate groups at 9 months, with similar results at 1 year. The results of this study demonstrate the profile of IV ibandronate, which allows it to be dosed as an IV injection in the primary care setting without the need for an infusion, even in patients with pre-existing hypertension or diabetes mellitus.

Safety of long-term bisphosphonate therapy for the management of osteoporosis

Drugs in the bisphosphonate class are the most commonly prescribed therapeutic agents for the treatment of osteoporosis. Prospective, randomized, placebo-controlled clinical trials have demonstrated efficacy in reducing fracture risk, with favourable safety profiles, in women with postmenopausal osteoporosis. However, long-term use in clinical practice has been associated with reports of undesirable events not previously recognized. These have included gastrointestinal intolerance, osteonecrosis of the jaw, atypical femur fractures, oesophageal cancer, atrial fibrillation and chronic musculoskeletal pain. Physicians must be alert to newly recognized safety concerns, understand the level of evidence supporting them and be able to effectively communicate the balance of expected benefit and potential risk to patients. Usually, post-marketing adverse events are first presented as case reports or observational studies with variable levels of supporting evidence for plausibility, pathophysiology and causality. Widespread coverage in the news media, which can be alarming to patients and their physicians, may not present a balanced view of the proven benefits, the uncertain risks of therapy and the relative magnitude of these events. There may be confusion about the risks associated with bisphosphonate use for the treatment of osteoporosis versus treatment of other conditions, such as cancer, which typically involves a very different patient population and different doses or frequency of drug administration. Often reports of possible adverse events do not provide information on the number of patients exposed to the drug in proportion to the reported adverse event, or do not describe the incidence of the adverse event in a comparator population not exposed to the drug. Gastrointestinal intolerance with oral bisphosphonates, and hypocalcaemia, acute phase reactions and renal toxicity with intravenous bisphosphonates are characterized by biological plausibility and demonstration of causality. Safety concerns with uncertain biological plausibility and unproven causality include osteonecrosis of the jaw, atypical femur fractures, oesophageal cancer and ocular inflammation. Suspected concerns that are unlikely to be causally related include atrial fibrillation and hepatotoxicity. When making the decision to use a bisphosphonate for the treatment of osteoporosis, the balance between benefit and potential risks according to clinical circumstances of each patient should be considered.

The kidney and bisphosphonates

Bisphosphonates are eliminated from the human body by the kidney. Renal clearance is both by glomerular filtration and proximal tubular secretion. Bisphosphonates given rapidly in high doses in animal models have induced a variety of adverse renal effects, from glomerular sclerosis to acute tubular necrosis. Nevertheless in the doses that are registered for the management of postmenopausal osteoporosis (PMO), oral bisphosphonates have never been shown to adversely affect the kidney, even (in post-hoc analysis of clinical trial data) down to estimated glomerular filtration rates of 15 ml/min. In addition fracture risk reduction has also been observed in these populations with stage 4 chronic kidney disease (CKD) with age-related reductions in glomerular filtration rate (GFR). Intravenous zoledronic acid is safe when the infusion rate is no faster than 15 min though there have been short-term (days 9-11 post-infusion) increases in serum creatinine concentrations in a small sub-set of patients from the postmenopausal registration trials. For these reasons intravenous zoledronic acid should be avoided in patients with GFR levels <35 ml/min; and the patients should be well hydrated and have avoided the concomitant use of any agent that may impair renal function. Intravenous ibandronate has not to date been reported to induce acute changes in serum creatinine concentrations in the PMO clinical trial data, but the lack of head-to-head comparative data between ibandronate and zoledronic acid precludes knowing if one intravenous bisphosphonate is safer than the other. In patients with GFR levels <30-35 ml/min, the correct diagnosis of osteoporosis becomes more complex since other forms of renal bone disease, which require different management strategies than osteoporosis, need to be excluded before the assumption can be made that fractures and/or low bone mass are due to osteoporosis. In addition, in patients who may have pre-existing adynamic renal bone disease, there is a lack of evidence of any beneficial effect or harm by reducing bone turnover by any pharmacological agent, including bisphosphonates on bone strength or vascular calcification. Bisphosphonates are safe and effective for the management of osteoporosis when used in the right dose and in the right patient population for the right duration.

Osteoporosis following organ transplantation: pathogenesis, diagnosis and management

Organ transplantation has become popular for the management of various chronic illnesses. With the advent of modern immunosuppressive treatments, the longevity of transplant recipients has increased. Consequently, morbid complications such as osteoporosis and bone fractures are seen at an increasing frequency in this population. In most transplant recipients, bone mineral density (BMD) falls shortly after transplantation. However, bone fracture rate plateaus in all except for post-renal transplant patients. Although the underlying pathophysiologic mechanism for this difference is not fully understood, potential mechanisms for sustained bone loss in renal transplant recipients may be persistent phosphorus wasting and defective bone mineralization. Current treatment regimens are based on studies in a small numbers of subjects with BMD as the primary outcome. Although BMD is recognized as a gold standard in the assessment of bone fracture risk, to date, its association with bone fracture risk in the general post-transplant population is not robust. Therefore, randomized controlled trials with bone fracture as the primary end point are crucial. The development of noninvasive bone markers in distinguishing bone turnover and bone mineralization status is also pivotal since skeletal lesions are heterogeneous in various organ transplantations. The elucidation of these underlying skeletal lesions is necessary for the consideration of selective treatment in this population.

Osteoporosis update from the 2010 santa fe bone symposium

The 11th Santa Fe Bone Symposium was held in Santa Fe, NM, USA, on August 6-7, 2010. This annual event addresses clinically relevant advances in the fields of osteoporosis and metabolic bone disease. The venue includes plenary presentations by internationally recognized experts, oral presentations of abstracts, and interactive panel discussions of challenging cases and controversial issues. Attendees are active participants throughout the symposium program. Topics for the 2010 symposium included potential applications of novel technologies for the assessment of skeletal health for research and clinical practice; new and emerging treatments for osteoporosis; appropriate use of pharmacological agents to prevent osteoporosis; controversies with bisphosphonate therapy; practical applications of the World Health Organization fracture risk assessment tool (FRAX; World Health Organization Collaborating Centre for Metabolic Bone Diseases, University of Sheffield, UK); insights into the use of osteoanabolic agents to enhance fracture healing; and challenges in laboratory testing in the assessment of factors contributing to skeletal fragility. Concurrent sessions focused on critical thinking for technologists in the acquisition and analysis of data with dual-energy X-ray absorptiometry. The key messages from each presentation, including the best available medical evidence and potential current and future clinical applications, are provided here.

Intravenous zoledronic acid for the treatment of osteoporosis: The evidence of its therapeutic effect

INTRODUCTION

Osteoporosis is a disease characterized by low bone mineral density and poor bone quality resulting in reduced bone strength and increased risk of fracture. Oral bisphosphonates, first-line therapy for most patients with osteoporosis, are associated with suboptimal adherence to therapy due to factors that include a complex dosing regimen and gastrointestinal intolerance in some patients. Intravenous bisphosphonates address these limitations through infrequent injectable dosing that assures 100% bioavailability. Intravenous zoledronic acid is the newest bisphosphonate to be approved for the treatment of osteoporosis.

AIMS

This review assesses the evidence for the therapeutic effects of intravenous zoledronic acid for the treatment of osteoporosis.

EVIDENCE REVIEW

Zoledronic acid 5 mg administered as an annual 15-min intravenous infusion has been shown to reduce the risk of vertebral fractures, hip fractures, and other fractures in a three-year randomized, double-blind, placebo-controlled trial in women with postmenopausal osteoporosis. In a randomized, double-blind, placebo-controlled trial in women and men with a recent surgical repair of low-trauma hip fracture, it reduced the risk of new clinical fractures and improved survival. In both studies, zoledronic acid was associated with a good safety profile and was generally well tolerated. Zoledronic acid has the potential to improve clinical outcomes by reducing the risk of fracture in patients with osteoporosis.

CLINICAL VALUE

Intravenous zoledronic acid 5 mg every 12 months reduces fracture risk in women with postmenopausal osteoporosis and in women and men with recent low-trauma hip fracture.

Bisphosphonates for the treatment of osteoporosis: insights for clinicians

Osteoporosis is a common skeletal disease characterized by a reduction in bone strength and increased risk of fractures. Osteoporotic fractures are associated with substantial morbidity, mortality, and high healthcare costs. Treatments for osteoporosis have been shown to increase bone strength and reduce fracture risk. The drugs most commonly used to treat osteoporosis are bisphosphonates: stable analogs of naturally occurring inorganic pyrophosphate. The bisphosphonates share a common chemical structure with side chain variations that convey differences in their pharmacological properties, such as affinity for bone mineral and inhibitory effect on osteoclastic bone resorption. The clinical profiles of bisphosphonates, such as time of onset and offset of effect, may differ according to these pharmacological properties. Bisphosphonates can be administered orally or intravenously with a wide range of doses and dosing intervals. Randomized placebo-controlled clinical trials have shown that bisphosphonates reduce fracture risk in postmenopausal women with osteoporosis and have a generally excellent safety record. Clinical challenges in using bisphosphonates to treat osteoporosis include appropriate selection of patients for initiating therapy, choosing which bisphosphonate to use, monitoring therapy to assure that medication is taken correctly and the desired effect is achieved, determining when drug discontinuation should be considered, and managing side effects, possible side effects, and fear of side effects. Strategies for treating patients with bisphosphonates should consider each of these issues.

Long-term use of bisphosphonates in osteoporosis

CONTEXT

Bisphosphonates have been widely used in the treatment of osteoporosis. Uncommon side effects have emerged in postapproval use. Because bisphosphonates accumulate in bone and are released for months or years after treatment is stopped, it is reasonable to consider the clinical question of how long to treat.

OBJECTIVE

In this personal perspective, we review the pharmacology and mechanism of action of bisphosphonates and the clinical studies that support their efficacy. We then review the literature for longer-term studies and reports of possible side effects that were not seen in clinical trials.

RESULTS

Bisphosphonates have demonstrated antifracture efficacy in randomized, placebo-controlled trials of 3 and 4 yr duration and have been widely used since the initial release of alendronate in 1995. For zoledronic acid and risedronate, an early effect (fractures reduced within 6-12 months of starting therapy) has been shown. A sustained effect for risedronate has been shown through 5 yr and suggested through 7 yr. Ten-year data with alendronate and 8 yr data with risedronate indicated good tolerability and safety; it is unlikely that longer-term studies will be done. Side effects that emerged in clinical trials include esophageal irritation with oral administration and acute phase response with iv treatment or high-dose oral therapy. Uncommon side effects that have been noted with wide clinical use include osteonecrosis of the jaw, musculoskeletal complaints, and atypical fractures. The numbers of events are small, and a clear cause-and-effect relationship between these events and bisphosphonate treatment has not been established. Because bisphosphonates accumulate in bone, they create a reservoir leading to continued release from bone for months or years after treatment is stopped. Studies with risedronate and alendronate suggest that if treatment is stopped after 3-5 yr, there is persisting antifracture efficacy, at least for 1-2 yr.

CONCLUSIONS

Bisphosphonates are popular and effective for treatment of osteoporosis. Because they accumulate in bone and provide some residual antifracture reduction when treatment is stopped, we recommend a drug holiday after 5-10 yr of bisphosphonate treatment. The duration of treatment and length of the holiday are based on fracture risk and pharmacokinetics of the bisphosphonate used. Patients at mild risk might stop treatment after 5 yr and remain off as long as bone mineral density is stable and no fractures occur. Higher risk patients should be treated for 10 yr, have a holiday of no more than a year or two, and perhaps be on a nonbisphosphonate treatment during that time.

Pamidronate improves pain, wellbeing, fracture rate and bone density in 14 children and adolescents with chronic neurological conditions

OBJECTIVE

To investigate if intravenous pamidronate improves bone density in a cohort of patients with chronic neurological conditions and low bone density, in whom fractures and bone pain are impacting on care.

METHODS

Fourteen participants (M:F = 7:7, average age 12.4 years) were enrolled in a prospective uncontrolled study in which pamidronate was infused every 6-8 weeks over a 2 year period, the average dose received was 12.5 mg kg(-1).

RESULTS

Bone mineral density z-score improved at all sites measured over the 2 years; whole body -4.84 to -3.14 (p = 0.01), lumbar spine -2.92 to -1.1 (p = 0.02) and femoral neck -4.6 to -3.58 (p = 0.04). Of the eight patients with pain at baseline, seven reported decreased pain after 12 months of pamidronate. Of the 11 patients who answered the general wellbeing part of the questionnaire, eight patients reported an improvement in general wellbeing and three reported no change. There was a downward trend in the average annualized fracture rate from 0.42 to 0.14 fractures per year (p = 0.09).

CONCLUSION

Pamidronate improves bone density and reduces pain in children and adolescents with chronic neurological conditions.

Current options for the treatment of Paget's disease of the bone

Paget’s disease of bone (PDB) is a chronic bone remodelling disorder characterized by increased osteoclast-mediated bone resorption, with subsequent compensatory increases in new bone formation, resulting in a disorganized mosaic of woven and lamellar bone at affected skeletal sites. This disease is most often asymptomatic but can be associated with bone pain or deformity, fractures, secondary arthritis, neurological complications, deafness, contributing to substantial morbidity and reduced quality of life. Neoplastic degeneration of pagetic bone is a relatively rare event, occurring with an incidence of less than 1%, but has a grave prognosis. Specific therapy for PDB is aimed at decreasing the abnormal bone turnover and bisphosphonates are currently considered the treatment of choice. These treatments are associated with a reduction in plasma alkaline phosphatase (ALP) activity and an improvement in radiological and scintigraphic appearance and with a reduction in bone pain and bone deformity, Recently, the availability of newer, more potent nitrogen-containing bisphosphonates has improved treatment outcomes, allowing a more effective and convenient management of this debilitating disorder.

Diagnosis and treatment of osteoporosis in chronic renal disease

Osteoporosis is the most prevalent metabolic bone disease leading to low-trauma (fragility) fractures worldwide. There is no reason why osteoporosis, as defined by different criteria, cannot accompany the derangements in bone metabolism that characterize chronic kidney disease (CKD). In fact, osteoporosis could and should be included in the broad characterization of CKD-mineral and bone disorder (CKD-MBD), as recently proposed by the Kidney Disease: Improving Global Outcomes working group. The pathophysiology leading to osteoporosis or CKD-MBD shares many common yet distinctly different pathways. Both pathways may lead to impairment of bone strength and low-trauma fractures. The challenge for clinical practice is how to discriminate between osteoporosis and CKD-MBD in fracturing patients. There is agreement that in the absence of aberrant biochemical tests suggesting CKD-MBD in stages 1 through 3 CKD, osteoporosis can be diagnosed using the World Health Organization criteria or development of low-trauma fractures. The distinction between osteoporosis and CKD-MBD becomes more difficult in stages 4 and 5 through 5D CKD. In fracturing patients with these levels of severe CKD, careful biochemical assessment of bone turnover markers and, in selected cases, bone biopsy is needed to eliminate CKD-MBD and to diagnose osteoporosis by exclusion. In stages 1 through 3 CKD, the current registered osteoporosis pharmacologic therapies can be used to treat osteoporosis. In stage 4, 5, and 5D these agents can be considered off-label, but only after very careful considerations and only in fracturing patients without CKD-MBD. We need better noninvasive means of discriminating among all these metabolic bone diseases and prospective data to guide us to the use of agents that alter bone remodeling in high-risk patients with more severe CKD.

2008 Santa Fe Bone Symposium: update on osteoporosis

The Ninth Annual Santa Fe Bone Symposium was held on August 1-2, 2008, in Santa Fe, New Mexico, USA. The symposium faculty presented the current best evidence on selected topics of clinical relevance in the fields of osteoporosis, metabolic bone disease, and assessment of skeletal health. The educational venues were in the form of didactic presentations, panel discussions, challenging cases, and numerous interactive discussions. Knowledge of basic science and clinical trials was applied to real-world patient scenarios that were discussed by faculty experts and clinician participants. Topics included an update on the rationale and development of new agents for the treatment of osteoporosis, the use of bone turnover markers in clinical practice, hospital-based pathways for the management of hip fracture patients, injectable bisphosphonates for the treatment of osteoporosis, combination therapy with anabolic and antiresorptive agents, and assessment of skeletal health with devices other than central dual-energy X-ray absorptiometry. This is a collection of scientific essays based on presentations and discussions at the 2008 Santa Fe Bone Symposium.

Safety of bisphosphonates in the treatment of osteoporosis

In this review 4 experts consider the major safety concerns relating to bisphosphonate therapy for osteoporosis. Specific topics covered are skeletal safety (particularly with respect to atypical fractures and delayed healing), gastrointestinal intolerance, hypocalcemia, acute-phase (i.e., postdose) reactions, chronic musculoskeletal pain, renal safety, and cardiovascular safety (specifically, atrial fibrillation).

Bisphosphonates in the management of postmenopausal osteoporosis--optimizing efficacy in clinical practice

Nitrogen-containing bisphosphonates are potent inhibitors of osteoclastic bone resorption. With their individually proven efficacy to significantly reduce the incidence of vertebral and/or non-vertebral fractures and with their overall beneficial safety profile, alendronate, ibandronate, risedronate, and zoledronate are considered today a treatment of first choice in postmenopausal osteoporosis. However, treatment effects in an individual patient and cost-effectiveness in public health perspective are vitally dependent on the long-term patient adherence as well as on compliance and persistence. As compliance and persistence with daily oral bisphosphonates are shown to be suboptimal in many patients, leading to an increased fracture incidence in non-compliant patients, there is a need to improve overall adherence for bisphosphonate treatment in order to achieve maximum treatment effects. One option is to extend dosing intervals to weekly (alendronate, risedronate) or monthly (ibandronate) oral regimens. Less frequent oral regimens are generally preferred by majority of patients. Another alternative is intravenous, instead of oral application (ibandronate, zoledronate). Treatment acceptance could be further improved by IV bisphosphonates with their benefit of only quarterly, or even once-yearly, application. Treatment decisions should be based on anti-fracture efficacy data first. In addition, to ensure best possible patient adherence and maximum treatment benefits, physicians should consider individual patient conditions affecting compliance and persistence as well as patient preferences.

Anti-resorptives in the management of osteoporosis

Bone-active agents that decrease bone turnover (the anti-resorptive agents) have been, to date, the most thoroughly studied pharmacological agents for the management of osteoporosis in a variety of populations - postmenopausal, male, and glucocorticoid-induced osteoporosis - and have received both Food and Drug Administration (FDA) and Committee for Medicinal Products for Human Use (CHMP) as well as other worldwide registrations for the management of these conditions. While the mechanisms of action of 'anti-resorptives' as a class differ, their effect on increasing bone strength and reducing the risk of fragility fractures share common pathways: an increase in bone mineral content, and a reduction in bone turnover. Within the category of anti-resorptives: estrogen, selective estrogen receptor modulators, tibolone, calcitonin, bisphosphonates and denosumab all reduce vertebral fractures risk, but differ in their ability to reduce the risk of non-vertebral fractures in randomized clinical trials. This chapter will discuss the data on these effects for each class of anti-resorptive agent.

Non-crystalline and crystalline rheumatic disorders in chronic kidney disease

Rheumatic syndromes are cause for morbidity in patients with end-stage renal disease. Recent advances in understanding the role of tissue remodeling have provided insight into the pathogenic mechanisms responsible for some of these manifestations. Here, we survey recent and clinically relevant advances in translational research that impact our understanding of rheumatic syndromes seen in patients with significant renal disease. The management of acute and chronic crystalline arthropathies in chronic kidney disease and hemodialysis patients is discussed.

Biodistribution and plasma protein binding of zoledronic acid

The bisphosphonate zoledronic acid is a potent inhibitor of osteoclast-mediated bone resorption. To investigate drug biodistribution and elimination, (14)C-zoledronic acid was administered intravenously to rats and dogs in single or multiple doses and assessed for its in vitro blood distribution and plasma protein binding in rat, dog, and human. Drug exposure in plasma, bones, and noncalcified tissues was investigated up to 240 days in rats and 96 h in dogs using radiometry after dissection. Drug biodistribution in the rat and within selected bones from dog was assessed by autoradiography. Concentrations of radioactivity showed a rapid decline in plasma and noncalcified tissue but only a slow decline in bone, to approximately 50% of peak at 240 days post dose, whereas the terminal half-lives (50-200 days) were similar in bone and noncalcified tissues, suggesting redistribution of drug from the former rather than prolonged retention in the latter. Uptake was highest in cancellous bone and axial skeleton. At 96 h after dose, the fraction of dose excreted was 36% in rat and 60% in dog; 94 to 96% of the excreted radioactivity was found in urine. Blood/plasma concentration ratios were 0.52 to 0.59, and plasma protein binding of zoledronic acid was moderate to low in all species. The results suggest that a fraction of zoledronic acid is reversibly taken up by the skeleton, the elimination of drug is mainly by renal excretion, and the disposition in blood and noncalcified tissue is governed by extensive uptake into and slow release from bone.