Treatment of osteoporosis with bisphosphonates

Risedronate for the primary and secondary prevention of osteoporotic fractures in postmenopausal women

BACKGROUND

Osteoporosis is an abnormal reduction in bone mass and bone deterioration leading to increased fracture risk. Risedronate belongs to the bisphosphonate class of drugs which act to inhibit bone resorption by interfering with the activity of osteoclasts. This is an update of a Cochrane Review that was originally published in 2003.

OBJECTIVES

We assessed the benefits and harms of risedronate in the primary and secondary prevention of osteoporotic fractures for postmenopausal women at lower and higher risk for fractures, respectively.

SEARCH METHODS

With broader and updated strategies, we searched the Cochrane Central Register of Control Trials (CENTRAL), MEDLINE and Embase. A grey literature search, including the online databases ClinicalTrials.gov, International Clinical Trials Registry Platform (ICTRP), and drug approval agencies, as well as bibliography checks of relevant systematic reviews was also performed. Eligible trials published between 1966 to 24 March 2021 were identified.

SELECTION CRITERIA

We included randomised controlled trials that assessed the benefits and harms of risedronate in the prevention of fractures for postmenopausal women. Participants must have received at least one year of risedronate, placebo or other anti-osteoporotic drugs, with or without concurrent calcium/vitamin D. Major outcomes were clinical vertebral, non-vertebral, hip and wrist fractures, withdrawals due to adverse events, and serious adverse events. In the interest of clinical relevance and applicability, we classified a study as secondary prevention if its population fulfilled more than one of the following hierarchical criteria: a diagnosis of osteoporosis, a history of vertebral fractures, low bone mineral density (BMD)T score ≤ -2.5, and age ≥ 75 years old. If none of these criteria was met, the study was considered to be primary prevention.

DATA COLLECTION AND ANALYSIS

We used standard methodology expected by Cochrane. We pooled the relative risk (RR) of fractures using a fixed-effect model based on the expectation that the clinical and methodological characteristics of the respective primary and secondary prevention studies would be homogeneous, and the experience from the previous review suggesting that there would be a small number of studies. The base case included the data available for the longest treatment period in each placebo-controlled trial and a >15% relative change was considered clinically important. The main findings of the review were presented in summary of findings tables, using the GRADE approach. In addition, we looked at benefit and harm comparisons between different dosage regimens for risedronate and between risedronate and other anti-osteoporotic drugs.

MAIN RESULTS

Forty-three trials fulfilled the eligibility criteria, among which 33 studies (27,348 participants) reported data that could be extracted and quantitatively synthesized. We had concerns about particular domains of risk of bias in each trial. Selection bias was the most frequent concern, with only 24% of the studies describing appropriate methods for both sequence generation and allocation concealment. Fifty per cent and 39% of the studies reporting benefit and harm outcomes, respectively, were subject to high risk. None of the studies included in the quantitative syntheses were judged to be at low risk of bias in all seven domains. The results described below pertain to the comparisons for daily risedronate 5 mg versus placebo which reported major outcomes. Other comparisons are described in the full text. For primary prevention, low- to very low-certainty evidence was collected from four studies (one to two years in length) including 989 postmenopausal women at lower risk of fractures. Risedronate 5 mg/day may make little or no difference to wrist fractures [RR 0.48 ( 95% CI 0.03 to 7.50; two studies, 243 participants); absolute risk reduction (ARR) 0.6% fewer (95% CI 1% fewer to 7% more)] and withdrawals due to adverse events [RR 0.67 (95% CI 0.38 to 1.18; three studies, 748 participants); ARR 2% fewer (95% CI 5% fewer to 1% more)], based on low-certainty evidence. However, its preventive effects on non-vertebral fractures and serious adverse events are not known due to the very low-certainty evidence. There were zero clinical vertebral and hip fractures reported therefore the effects of risedronate for these outcomes are not estimable.  For secondary prevention, nine studies (one to three years in length) including 14,354 postmenopausal women at higher risk of fractures provided evidence. Risedronate 5 mg/day probably prevents non-vertebral fractures [RR 0.80 (95% CI 0.72 to 0.90; six studies, 12,173 participants); RRR 20% (95% CI 10% to 28%) and ARR 2% fewer (95% CI 1% fewer to 3% fewer), moderate certainty], and may reduce hip fractures [RR 0.73 (95% CI 0.56 to 0.94); RRR 27% (95% CI 6% to 44%) and ARR 1% fewer (95% CI 0.2% fewer to 1% fewer), low certainty]. Both of these effects are probably clinically important. However, risedronate's effects are not known for wrist fractures [RR 0.64 (95% CI 0.33 to 1.24); three studies,1746 participants); ARR 1% fewer (95% CI 2% fewer to 1% more), very-low certainty] and not estimable for clinical vertebral fractures due to zero events reported (low certainty). Risedronate results in little to no difference in withdrawals due to adverse events [RR 0.98 (95% CI 0.90 to 1.07; eight studies, 9529 participants); ARR 0.3% fewer (95% CI 2% fewer to 1% more); 16.9% in risedronate versus 17.2% in control, high certainty] and probably results in little to no difference in serious adverse events [RR 1.00 (95% CI 0.94 to 1.07; six studies, 9435 participants); ARR 0% fewer (95% CI 2% fewer to 2% more; 29.2% in both groups, moderate certainty).

AUTHORS' CONCLUSIONS

This update recaps the key findings from our previous review that, for secondary prevention, risedronate 5 mg/day probably prevents non-vertebral fracture, and may reduce the risk of hip fractures. We are uncertain on whether risedronate 5mg/day reduces clinical vertebral and wrist fractures.  Compared to placebo, risedronate probably does not increase the risk of serious adverse events.  For primary prevention, the benefit and harms of risedronate were supported by limited evidence with high uncertainty.

Bisphosphonates in Dialysis and Transplantation Patients: Efficacy and Safety Issues

Bisphosphonates are an old class of compounds. They were used in the 1930s as antiscaling and anticorrosion agents in washing powders and water to prevent the deposition of calcium crystals. Those basic functions were later utilized in an attempt to prevent ectopic calcifications in humans. The early studies demonstrated that bisphosphonates had a strong affinity for bone. That property was first exploited when the compounds were used for “bone scans.”

Currently, the drugs are used for treatment of hypercalcemic conditions, abnormal bone remodelling, Paget disease, malignancy, and osteoporosis. Bisphosphonates have several important toxicities: acute renal failure, worsening renal function, reduced bone mineralization, and osteomalacia. For those reasons and others, this class of drugs has not yet been approved for use in children or in patients with severe renal insufficiency.

The present review covers several aspects of bisphosphonates: molecular structure, routes of administration, pharmacology, mechanisms of action, toxicities, and exceptional uses in children with renal disease.

The Established Nuclear Medicine Modalities for Imaging of Bone Metastases

Background:

The skeleton is one of the frequent site of metastases in advanced cancer. Prostate, breast and renal cancers mostly metastasize to bone.

Discussion:

Malignant tumors lead to significant morbidity and mortality. Identification of bone lesions is a crucial step in diagnosis of disease at early stage, monitoring of disease progression and evaluation of therapy. Diagnosis of cancer metastases is based on uptake of bone-targeted radioactive tracer at different bone remodeling sites.

Conclusion:

This manuscript summarizes already established and evolving nuclear medicine modalities (e.g. bone scan, SPECT, SPECT/CT, PET, PET/CT) for imaging of bone metastases.

Long-Term Bisphosphonate Therapy in Osteogenesis Imperfecta

PURPOSE OF REVIEW

Osteogenesis imperfecta (OI) is a genetic bone disorder resulting in bone fragility. It has a heterogeneous phenotype which typically includes reduced bone mass, multiple fractures, deformity, and chronic disability. Bisphosphonate treatment remains the first-line medical management, but there is still debate on aspects of its effectiveness. This review summarizes current knowledge about long-term bisphosphonate use in OI with recommendations on clinical application.

RECENT FINDINGS

Bisphosphonates increase bone mineral density, most notably of the vertebrae, and reduce fracture risk in the pediatric OI population. Gains in strength and mobility, together with the permissive effect on orthopedic surgery (e.g., in combination with intramedullary rodding) and physiotherapy, have resulted in improved quality of life for those with OI. As experience in its use continues, the risks and benefits of long-term bisphosphonate treatment in OI are slowly emerging. Patient registries containing data on genotype, phenotype, fractures, bisphosphonate treatment, orthopedic intervention, and functional outcomes are essential for systematic evaluation given the lack of large multi-centered randomized control trials.

Evaluation of dental implants as a risk factor for the development of bisphosphonate-related osteonecrosis of the jaw in breast cancer patients

It remains unclear whether dental implants are a risk factor for the development of bisphosphonate-related osteonecrosis of the jaw (BRONJ). We retrospectively evaluated the status of dental implants in patients given intravenous bisphosphonates (BPs) in a breast cancer cohort to elucidate the risk for BRONJ at the implant site. We established a BRONJ oral monitoring program for 247 breast cancer patients given intravenous BP in our institution. The 3-year cumulative incidence rate was determined. The systemic and local risk factors of 44 patients who completed comprehensive oral examinations were evaluated by logistic regression analysis. The 3-year cumulative incidence rate of the 247 patients was 0.074 % (8/247, 95 % CI 0.0081-0.014). In the 44 orally examined patients, 6 (13.6 %: 6/44) had dental implants. Of these 6 patients, 1 developed BRONJ at the implant site. There were no significant differences in the age, total BP treatment period, number of residual teeth, time of regular oral monitoring, oral hygiene level, or dental implant insertion. Although a case of ONJ was identified, dental implants which were inserted before intravenous BP administration were not a risk factor for the development of ONJ in breast cancer patients.

Effect of bisphosphonates on orthodontic tooth movement-an update

Bisphosphonates are a synthetic class of pyrophosphate analogues that are powerful inhibitors of bone resorption which are commonly used as a medication for the prevention and therapy of osteoporosis and osteopenia, also used to treat tumor diseases. As it affects bone metabolism, it is said to have an influence on orthodontic treatment and tooth movement. Also, this review gives an insight into the reported effects of Bisphosphonate medication in literature highlighting the status quo of scientific research regarding effects of Bisphosphonates on orthodontic tooth movement. A systematic literature search was done in Medline database (Pubmed) for the appropriate keywords. Manual handsearch was also done. From the available evidence it can be concluded that the duration of orthodontic treatment is increased for patients under Bisphosphonate therapy as they interfere with the osteoclastic resorption. However, they may be beneficial for anchorage procedures. Further long term prospective randomized controlled trials are required to assess possible benefits and adverse effects of bisphosphonate treatment, before Bisphosphonates can be therapeutically used in orthodontics.

Characteristics of the early stages of intravenous bisphosphonate-related osteonecrosis of the jaw in patients with breast cancer

OBJECTIVE

The clinical features of the early stages of bisphosphonate-related osteonecrosis of the jaw (BRONJ) in patients with breast cancer remain unclear. A retrospective cohort study was conducted of patients with breast cancer who received intravenous bisphosphonate (BP) treatment in a single center in order to clarify the status of the early stages of BRONJ.

MATERIALS AND METHODS

A BRONJ oral monitoring program was established in 247 breast cancer patients given intravenous BP treatment at the institution. The differences in age, BP treatment period, number of remaining teeth, oral hygiene status, presence of regular oral monitoring and the existence of suspected BRONJ (stage 0) among eight BRONJ and 36 non-BRONJ subjects who completed oral examinations were then compared.

RESULTS

BRONJ was observed in 0.4% of subjects on the first visit to the oral surgery clinic and in 3.2% of subjects during the follow-up period. Logistic regression analysis revealed that the odds ratio for identifying patients with BRONJ during follow-up by the presence of stage 0 at first visit was 24.0 (95% confidence interval [CI] = 3.6-161.7). The area under the receiver operating characteristic curve for identifying subjects with BRONJ by the presence of stage 0 was 0.82 (95% CI = 0.63-1.00).

CONCLUSION

The results suggest that patients with stage 0 BRONJ on the first visit may progress to advanced BRONJ during the follow-up period. The oral monitoring program may contribute to the early detection of BRONJ.

Immunohistochemical expression of caspase-3, caspase-5, caspase-7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats exposed to zoledronic acid (ZOL) and basic fibroblast growth factor (bFGF)

BACKGROUND

Bisphosphonates (BPs) like zoledronic acid (ZOL) are widely used for the treatment of different diseases such as osteoporosis, metastatic bone diseases and hypercalcaemia. However, the effects of BPs on apoptosis of the liver and kidney after treatment are unclear. Furthermore, basic fibroblast growth factor (bFGF) is an angiogenic molecule, which plays an important role in angiogenesis and tissue repair. The present study investigated the expression of caspase-3, -5, -7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats treated with ZOL and bFGF.

OBJECTIVE

The present study investigated the expression of caspase-3, -5, -7 and apoptotic protease-activating factor-1 (APAF-1) in the liver and kidney of rats treated with ZOL and bFGF.

ANIMALS AND METHODS

An animal model with 32 male Sprague Dawley rats was used. The effects of ZOL and bFGF on liver and kidney with the expressions of different apoptosis markers were studied histopathologically and immunohistochemically. Data were analyzed using Cronbach's alpha, Kruskal-Wallis and Bonnferroni-Dunn tests.

RESULTS

The main microscopic findings were mononuclear cell infiltrations around the bile ducts, binuclear and markedly enlarged hepatocytes (cytomegaly) and mitotic figures in the liver of rats treated with ZOL only. Immunohistochemically, both APAF-1 and caspase-3, -5 and -7 expressions were found elevated significantly (P < 0.05) in the liver and kidney of these rats.

CONCLUSIONS

Our findings showed that ZOL treatment increased while bFGF treatment decreased apoptosis significantly in the liver and kidney of Sprague Dawley rats.

CLINICAL IMPORTANCE

The addition of bFGF to ZOL treatment of various diseases might reduce the ZOL effects.

Oral alendronate can suppress bone turnover but not fracture in kidney transplantation recipients with hyperparathyroidism and chronic kidney disease

Post-transplantation bone diseases negatively affect the quality of life of solid organ recipients. Secondary or tertiary hyperparathyroidism is a frequent complication in kidney transplantation (KTx) recipients. Treatment with immunosuppressive agents including glucocorticoids can lead to deterioration in bone metabolism in these patients. In the present study, we explored the effects of a three-year treatment period with oral alendronate (ALN) in long-term KTx recipients. Post-KTx recipients were recruited (n = 24, M/F = 12/12, mean age 52.0 ± 7.8 years) into this study. All patients were prescribed methylprednisolone (4.07 ± 0.86 mg/day) with various immunosuppressive agents. Before treatment with oral ALN (35 mg/week), the mean concentrations of intact parathyroid hormone (iPTH) and 25-hydroxyvitamin D were 139.2 ± 71.4 pg/mL and 20.8 ± 4.1 ng/mL, respectively. After 36 months of ALN treatment, mean iPTH levels increased slightly (+20.9 %). Treatment with ALN reduced bone-specific alkaline phosphatase (-35.4 %), serum type I collagen N-terminal telopeptide (-31.2 %) and osteocalcin (-55.6 %) levels. ALN did not increase bone mass after 24 months. Four patients with the highest baseline iPTH levels suffered a clinical osteoporotic fracture during the 36-month ALN treatment period. Higher iPTH levels with chronic kidney disease (CKD) at baseline were associated with the incidence of new clinical fractures during ALN treatment. In conclusion, anti-resorptive therapy with ALN can suppress bone turnover even when iPTH concentration is elevated in long-term KTx recipients. However, hyperparathyroidism with CKD seems to be associated with new clinical fractures during ALN treatment.

Effect of rosiglitazone on bone quality in a rat model of insulin resistance and osteoporosis

OBJECTIVE

Rosiglitazone (RSG) is an insulin-sensitizing drug used to treat type 2 diabetes mellitus. The A Diabetes Outcome Progression Trial (ADOPT) shows that women taking RSG experienced more fractures than patients taking other type 2 diabetes drugs. These were not osteoporotic vertebral fractures but, rather, occurred in the limbs. The purpose of this study was to investigate how RSG treatment alters bone quality, which leads to fracture risk, using the Zucker fatty rat as a model.

RESEARCH DESIGN AND METHODS

A total of 61 female 4-month-old rats were divided into six groups. One Sham group was a control and another was administered oral RSG 10 mg/kg/day. Four ovariectomized (OVX) groups were dosed as follows: controls, RSG 10 mg/kg, alendronate (ALN, injected at 0.7 mg/kg/week), and RSG 10 mg/kg plus ALN. After 12 weeks of treatment, bone quality was evaluated by mechanical testing. Microarchitecture, bone mineral density (BMD), cortical bone porosity, and bone remodeling were also measured.

RESULTS

OVX RSG 10 mg/kg rats had lower vertebral BMD and compromised trabecular architecture versus OVX controls. Increased cortical bone porosity and decreased mechanical properties occurred in these rats. ALN treatment prevented decreased BMD and architectural and mechanical properties in the OVX model. Reduced bone formation, increased marrow adiposity, and excess bone resorption were observed in RSG-treated rats.

CONCLUSIONS

RSG decreases bone quality. An unusual finding was an increase in cortical bone porosity induced by RSG, consistent with its effect on long bones of women. ALN, an inhibitor of bone resorption, enhanced mechanical strength and may provide an approach to partially counter the deleterious skeletal effects of RSG.

[Optimizing orthodontic treatment in patients taking bisphosphonates]

Bisphosphonates have unique pharmacological characteristics unlike those of any other drug group. Millions of adults take oral bisphosphonates for long-term treatment of osteoporosis and osteopenia; some of these people will most likely also seek orthodontic treatment. Adverse dental effects from bisphosphonates have been reported, including decreased tooth movement, impaired bone healing, and osteonecrosis in the mandible and the maxilla. Osteonecrosis has been rarely observed after bisphosphonate use for osteoporosis. However, adverse drug effects might occur more frequently in orthodontic patients, and they would probably be noted before the end-stage pathology of osteonecrosis. Adverse effects during orthodontic treatment, including decreased tooth movement, could last for years after the drug therapy is stopped. Successful orthodontic treatment requires optimal bone healing to prevent excessive tooth mobility. Bisphosphonates appear to have two bone elimination rates - a fast elimination of weeks from the bone surface and a slow elimination of years after incorporation into the bone structure. This article presents methods to clinically and radiographically monitor orthodontic patients who are taking oral bisphosphonates. Efforts to minimize adverse effects and optimize orthodontic procedures with physician-approved drug holidays are discussed. The orthodontic treatment results of three patients who received bisphosphonate therapy are reported.

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.

Hydroxyapatite-collagen composites. Part I: can the decrease of the interactions between the two components be a physicochemical component of osteoporosis in aged bone?

The interactions of Type I acid soluble collagen (Col) with both carbonate-free hydroxyapatite (HA(1100)) and carbonate-rich one (CHA) were investigated. The aim was to ascertain whether the increase of bone CO(3) (2-) with ageing could relate to the disease known as osteoporosis. HA(1100)-Col and CHA-Col composites with various ratios were prepared and examined. Scanning electron microscopy and differential scanning calorimetry showed a stronger adhesion of the Col matrix to the granules of HA(1100) than to those of CHA. FT-IR spectroscopy showed that with HA(1100) both multiple hydrogen bonds of Col peptide -NH groups with HA PO(4) (3-), and electrochemical interactions between Col peptide -C=O groups and HA Ca(2+) were present. In the presence of CO(3) (2-), the interactions between -NH and phosphate were diminished, and Ca(2+) interacted more strongly with CO(3) (2-) than with peptide -C=O, so causing a separation between the two components of the bone extra-cellular matrix. The results obtained strengthen the hypothesis that the substitution of PO(4) (3-) ions by CO(3) (2-) ions in the HA lattice might be a significant component of osteoporosis, although further investigation is needed.

WITHDRAWN: Risedronate for the prevention and treatment of postmenopausal osteoporosis

BACKGROUND

Postmenopausal osteoporosis results in an increased susceptibility to low-trauma fractures due to reduced bone volume and microarchitectural deterioration. Risedronate, a third generation bisphosphonate, has been shown in multiple clinical trials to reduce fracture risk and improve bone mineral density in postmenopausal women with osteoporosis. First and second generation bisphosphonates are known to have gastrointestinal side-effects and risedronate may be better tolerated.

OBJECTIVES

To systematically review the efficacy of risedronate on bone density, and fracture reduction in postmenopausal women.

SEARCH STRATEGY

The Cochrane Controlled Trials Registry Medline, and Current Contents were searched from 1990 - 2001. The electronic search was supplemented by handsearching four osteoporosis journals and their conference proceedings, as well as contacting content experts and industry sources for unpublished data.

SELECTION CRITERIA

We included eight trials that randomised women to risedronate or an alternative (placebo or calcium and /or vitamin D) and measured bone mineral density for at least one year.

DATA COLLECTION AND ANALYSIS

For each trial three independent reviewers assessed the methodological quality and abstracted data. Data was extracted for outcomes of fracture, bone mineral density and adverse events. The more conservative random effects model was used to pool data. The quality of trials was assessed according to the Jadad five-point scale.

MAIN RESULTS

Both vertebral and non-vertebral fractures were statistically and clinically reduced with risedronate. Eleven out of one hundred women who received risedronate had a vertebral fracture compared to 17 out of one hundred of those who received calcium and vitamin D (pooled relative risk for vertebral fractures of 0.64 (95% CI 0.52 - 0.77). Three percent of participants who received risedronate had a non-vertebral fracture compared to 4.6% of those who received calcium and vitamin D (pooled relative risk for nonvertebral fractures of 0.73 (95% CI 0.61 - 0.87). The weighted mean difference for the percent change from baseline for bone mineral density with 5 mg daily for lumbar spine, femoral neck and trochanter was 4.54% (95%CI 4.12 - 4.97), p<0.01; 2.75% (95% CI 2.32 - 3.17), p<0.01; and 4.38% (95% CI 3.51 - 5.25), p<0.01 respectively.

AUTHORS' CONCLUSIONS

There is good evidence for the efficacy of risedronate in the reduction of both vertebral and non-vertebral fractures. In addition, there is evidence from randomized trials that risedronate is able to achieve this without increasing risk for overall withdrawals due to adverse effects.

Bisphosphonate treatment: An orthodontic concern calling for a proactive approach

The purpose of this article is to raise awareness among orthodontists of the effects of bisphosphonates, a commonly prescribed type of drug that can inhibit tooth movement and increase serious osteonecrosis risks in the alveolar bones of the maxilla and the mandible. Common medical uses of bisphosphonates, applicable pharmacology, pharmacokinetics, reports of impaired bone healing and induced osteonecrosis, and a drug effect accumulation theory are reviewed. Potential orthodontic issues and proposed orthodontic recommendations for intravenous and oral bisphosphonate treatments are discussed. Bisphosphonate medication screening, patient counseling, informed consent, and, perhaps, changes in treatment planning might be considered.

Low-level, high-frequency mechanical signals enhance musculoskeletal development of young women with low BMD

The potential for brief periods of low-magnitude, high-frequency mechanical signals to enhance the musculoskeletal system was evaluated in young women with low BMD. Twelve months of this noninvasive signal, induced as whole body vibration for at least 2 minutes each day, increased bone and muscle mass in the axial skeleton and lower extremities compared with controls.

INTRODUCTION

The incidence of osteoporosis, a disease that manifests in the elderly, may be reduced by increasing peak bone mass in the young. Preliminary data indicate that extremely low-level mechanical signals are anabolic to bone tissue, and their ability to enhance bone and muscle mass in young women was investigated in this study.

MATERIALS AND METHODS

A 12-month trial was conducted in 48 young women (15-20 years) with low BMD and a history of at least one skeletal fracture. One half of the subjects underwent brief (10 minutes requested), daily, low-level whole body vibration (30 Hz, 0.3g); the remaining women served as controls. Quantitative CT performed at baseline and at the end of study was used to establish changes in muscle and bone mass in the weight-bearing skeleton.

RESULTS

Using an intention-to-treat (ITT) analysis, cancellous bone in the lumbar vertebrae and cortical bone in the femoral midshaft of the experimental group increased by 2.1% (p = 0.025) and 3.4% (p < 0.001), respectively, compared with 0.1% (p = 0.74) and 1.1% (p = 0.14), in controls. Increases in cancellous and cortical bone were 2.0% (p = 0.06) and 2.3% (p = 0.04) greater, respectively, in the experimental group compared with controls. Cross-sectional area of paraspinous musculature was 4.9% greater (p = 0.002) in the experimental group versus controls. When a per protocol analysis was considered, gains in both muscle and bone were strongly correlated to a threshold in compliance, where the benefit of the mechanical intervention compared with controls was realized once subjects used the device for at least 2 minute/day (n = 18), as reflected by a 3.9% increase in cancellous bone of the spine (p = 0.007), 2.9% increase in cortical bone of the femur (p = 0.009), and 7.2% increase in musculature of the spine (p = 0.001) compared with controls and low compliers (n = 30).

CONCLUSIONS

Short bouts of extremely low-level mechanical signals, several orders of magnitude below that associated with vigorous exercise, increased bone and muscle mass in the weight-bearing skeleton of young adult females with low BMD. Should these musculoskeletal enhancements be preserved through adulthood, this intervention may prove to be a deterrent to osteoporosis in the elderly.

Skeletal effects of short-term exposure to dexamethasone and response to risedronate treatment studied in vivo in rabbits by magnetic resonance micro-imaging and spectroscopy

Supraphysiological levels of glucocorticoids (GC) cause bone atrophy and growth retardation. In this study, we examine whether these adverse structural effects are reversible and whether treatment with bisphosphonate is protective by in vivo serial micro-magnetic resonance (micro-MR) imaging and spectroscopy. Rabbits (n = 16) were divided into four groups, a control group (n = 4) and three groups (n = 4 each) receiving GC in the form of dexamethasone (0.45 mg/kg/day). In one of the GC groups dexamethasone exposure was discontinued after 2 weeks, the other two groups were maintained on dexamethasone, with one receiving risedronate (5 microg/kg twice per week) from the beginning of treatment, the other one receiving risedronate after 2 weeks. Animals were imaged at baseline and at 2, 4, and 8 weeks. Trabecular bone volume fraction (trabecular bone volume/tissue volume, TB/TV), trabecular bone thickness (Tb.Th), and topological structural parameters were measured in the distal femoral epiphysis, as was the epiphyseal growth plate (EGP), and marrow fat fraction, which was computed from the integrated proton spectra. Two weeks of dexamethasone exposure substantially reduced TB/TV, along with thinning of the epiphyseal growth plate and conversion of hematopoietic to adipocytic marrow. However, TB/TV recovered to normal levels within 2 weeks after cessation of GC exposure and remained constant throughout the remainder of the protocol. In contrast, neither EGP thickness nor marrow composition returned to control levels after cessation of GC exposure as rapidly as did TB/TV. Besides increased TB/TV, bisphosphonate treatment resulted in a more connected platelike network than observable at baseline, but GP atrophy and marrow conversion caused by GC exposure were not affected. The data lend support to a protective effect of risedronate on trabecular architecture during GC exposure. The improvement in trabecular network parameters beyond baseline values further suggest a therapeutic effect of risedronate.

Managing the care of patients with bisphosphonate-associated osteonecrosis

BACKGROUND

This position paper addresses the prevention of bisphosphonate-associated osteonecrosis (BON) and the management of care of patients with cancer and/or osteoporosis who are receiving bisphosphonates and who have BON or are at risk of developing it.

METHODS

The authors reviewed the literature available on this newly described oral complication. Information of interest included bisphosphonates, the medications associated with this oral complication; the patient population at risk of developing BON and the diseases being treated with this class of medications; the clinical presentation of the oral lesions; guidelines for managing the care of patients who develop BON; the prevention of this complication based on current knowledge; and recommendations for routine dental treatment of patients receiving bisphosphonates.

RESULTS

There is strong evidence that bisphosphonate therapy is the common link in patients with BON. The pathobiological mechanism leading to BON may have to do with the inhibition of bone remodeling and decreased intraosseous blood flow caused by bisphosphonates. People at risk include patients with multiple myeloma and patients with cancer metastatic to bone who are receiving intravenous bisphosphonates, as well as patients taking bisphosphonates for osteoporosis. The risk of developing complications appears to increase with time of use of the medication. There are no guidelines based on evidence, and the clinical management of the oral complication is based on expert opinion.

CONCLUSION

Prevention of BON is the best approach to management of this complication. Existing protocols to manage the care of patients who will receive radiation therapy or chemotherapy may be used until specific guidelines for BON are developed.

Safety and efficacy of risedronate in patients with age-related reduced renal function as estimated by the Cockcroft and Gault method: a pooled analysis of nine clinical trials

The incidences of osteoporosis and renal insufficiency increase with age. We studied the influence of renal function on the safety and efficacy of risedronate 5 mg daily in osteoporotic women. Risedronate was safe and effective in osteoporotic women with mild, moderate, or severe age-related renal impairment.

INTRODUCTION

The incidences of both osteoporosis and renal insufficiency increase with age; thus, the effect of renal impairment on the safety and efficacy of osteoporosis treatments is a clinical concern. Risedronate is a pyridinyl bisphosphonate well established as safe and effective in the treatment and prevention of osteoporosis. Currently, there is little available information about the effect of bisphosphonate treatment in patients with renal insufficiency. This retrospective analysis was conducted to study the influence of renal function on the safety and efficacy of risedronate in a population of osteoporotic women.

MATERIALS AND METHODS

Combined data from nine randomized, double-blind, placebo-controlled phase III risedronate trials were analyzed. The patients in these studies had no markedly abnormal laboratory parameters that were considered clinically significant and no evidence of significant disease. This analysis included patients who received placebo (n = 4,500) or risedronate 5 mg (n = 4,496) for up to 3 years (average duration of exposure, 2 years) and who had renal impairment (creatinine clearance [CrCl] < 80 ml/min). CrCl was estimated by the Cockcroft and Gault method, based on age, weight, and serum creatinine. Patients were categorized as having mild (CrCl >or=50 to <80 ml/min), moderate (CrCl >or=30 to <50 ml/min), or severe (CrCl < 30 ml/min) renal impairment.

RESULTS

Of the patients studied, renal impairment at baseline was mild in 48% (mean [range] serum creatinine, 0.9 [0.4-1.6] mg/dl), moderate in 45% (1.1 [0.6-1.9] mg/dl), and severe in 7% (1.3 [0.7-2.7] mg/dl). In both the placebo and risedronate treatment groups, the patients with the most severe renal impairment were older and had more severe osteoporosis. The incidences of overall adverse events and of renal function-related adverse events were similar in the placebo and risedronate 5 mg groups regardless of renal function. Furthermore, evaluation of changes from baseline in serum creatinine revealed no difference in renal function between the placebo and risedronate 5 mg groups in any of the renal impairment subgroups at any time-point. In all three subgroups, risedronate effectively preserved BMD and reduced the incidence of vertebral fractures.

CONCLUSIONS

These findings show that risedronate is safe and effective in osteoporotic women with age-related mild, moderate, or severe renal impairment.

Postmenopausal osteoporosis and alendronate

Osteoporosis is a systemic metabolic disorder associated with a decreased bone mass and resistance. Bisphosphonates suppress bone resorption and bone turnover by a mechanism that depends on their structure. They are characterized by low gastrointestinal absorption. In postmenopausal women, alendronate (ALN) reduces bone resorption markers and increases bone mineral density (BMD) in the lumbar spine, femoral neck, and total body. Individuals receiving ALN have been studied for up to 10 years with an apparent linear increase in BMD over that time period estimated at 13.7% at the lumbar spine. Treatment with ALN reduced the risk of both vertebral and non-vertebral fractures, including hip fractures, in postmenopausal women with osteoporosis. Direct comparisons of the results obtained with different antiresortive agents is difficult, because the designs of the respective studies, populations and other factors. However, the meta-analysis of available publications seems to indicate that ALN reduces the relative risk of vertebral fractures in a greater proportion than any other agent. Furthermore, ALN prevents the reduction in BMD after hormone replacement therapy discontinuation.

Discovery, clinical development, and therapeutic uses of bisphosphonates

OBJECTIVE

To review the literature concerning the history, development, and therapeutic uses of bisphosphonates.

DATA SOURCES

English-language articles were identified through a search of MEDLINE (through December 2004) using the key word bisphosphonate. Reference lists of pivotal studies, reviews, and full prescribing information for the approved agents were also examined.

STUDY SELECTION AND DATA EXTRACTION

Selected studies included those that discussed the discovery and initial applications of bisphosphonates, as well as their historical development, pharmacokinetic and pharmacodynamic properties, and current therapeutic uses.

DATA SYNTHESIS

Bisphosphonates structurally resemble pyrophosphates (naturally occurring polyphosphates) and have demonstrated similar physicochemical effects to pyrophosphates. In addition, bisphosphonates reduce bone turnover and resist hydrolysis when administered orally. The information gained from initial work with etidronate generated a considerable scientific effort to design new and more effective bisphosphonates. The PCP moiety in the general bisphosphonate structure is essential for binding to hydroxyapatite and allows for a number of chemical variations by changing the 2 lateral side chains (designated R(1) and R(2)). The R(1) side chain determines binding affinity to hydroxyapatite, and the R(2) side chain determines antiresorptive potency. Accordingly, each bisphosphonate has its own characteristic profile of activity.

CONCLUSIONS

The bisphosphonates reduce bone turnover, increase bone mass, and decrease fracture risk and therefore have a significant place in the management of skeletal disorders including osteoporosis, Paget's disease, bone metastases, osteogenesis imperfecta, and heterotopic ossification.

Relationship between age, renal function and bone mineral density in the US population

Bisphosphonate drugs for treating osteoporosis are excreted by the kidney. However, many of the major trials on efficacy and safety of the bisphophonates for treating osteoporosis excluded patients with significant renal compromise. Since both osteoporosis and renal insufficiency become more prevalent with age, it seems prudent for physicians to be aware of the prevalence of renal dysfunction in patients with osteoporosis who are candidates for treatment with bisphosphonates. Data on 13,831 men and women aged 20+ from the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III) were used to study the occurrence of compromise in renal clearance function in men and women with osteopenia and osteoporosis. To estimate creatinine clearance (CCr), a measure of renal function, serum creatinine (sCr), weight and age were inserted into the Cockcoft-Gault (C-G) formula. The World Health Organization gender specific bone mineral density (BMD) cut-offs were used to define the populations with osteopenia and osteoporosis. For women ages 20-80+ with osteoporosis, the percent prevalence (95% CI) for mild to moderate compromise of CCr </=60 ml/min is estimated to be 85% (79%, 91%) and for severe renal compromise of CCr <35 ml/min to be 24% (19%, 29%). In women with osteoporosis and severe compromise, the age specific prevalence is negligible through ages 50-59 and then rises steeply to 54% (46%, 62%) for ages 80+. Similarly, in women with osteopenia and severe renal compromise, the age specific prevalence is also negligible through ages 50-59 and then rises to 37% (28%, 45%) for ages 80+. Lower prevalence estimates hold for men with about 11% of men with osteoporosis having severe renal compromise as compared to 24% for women. These data suggest that there is a substantial prevalence of candidates for treatment of osteoporosis and osteopenia who have significant renal compromise but for whom there is a dearth of clinical trial data on the impact of treatment.

The efficacy of 48-week oral ibandronate treatment in postmenopausal osteoporosis when taken 30 versus 60 minutes before breakfast

Since effective prevention and treatment of osteoporosis demands a high degree of long-term compliance, optimization of the dosing regimen in terms of efficacy and convenience of drug intake is a critical issue of oral bisphosphonate treatment. The purpose of the present study was to investigate whether the efficacy of the treatment with oral ibandronate, 2.5 mg daily, can be maintained if changing the postdose fast from 60 to 30 min. This was a 48-week, multicenter, open-label, randomized, parallel-group noninferiority study. Subjects were postmenopausal women 55-80 years old with lumbar spine (L1-L4) bone mineral density (BMD) corresponding to a T score < or =2.5. Women were randomly assigned to take 2.5 mg ibandronate exactly 30 or 60 min before breakfast. Lumbar spine and proximal femur (trochanter, femoral neck, total hip) BMD were measured by dual energy X-ray absorptiometry; serum osteocalcin and creatinine-corrected urinary C-telopeptide of type I collagen (u-CTX/Cr) excretion were measured by ELISA. After 48 weeks of treatment, the relative increase in lumbar spine BMD from baseline in the 30-min fast group was lower than that in the 60-min fast group (3.07% versus 4.95%, one-sided 97.5% CI = -2.89%) such that the prespecified noninferiority criteria were not met. The mean relative increases in BMD at the trochanter (3.04% versus 4.36%), femoral neck (1.82% versus 2.19%), and total hip (2.35% versus 3.21%) in the 30-min fast group were also lower than those in the 60-min fast group. Less suppression of the markers of bone turnover (u-CTX/Cr, -48.5% vs -61.8%; serum osteocalcin, -34.8% vs 43.8%) was observed in the 30-min compared with the 60-min group. In conclusion, if reducing the postdose fasting interval, dose-increase compensation would likely to be required to maintain efficacy of oral ibandronate treatment. Another potential solution for improving the convenience with bisphosphonate treatment is expected from weekly or monthly dosing regimens currently under clinical investigations.

What predicts early fracture or bone loss on bisphosphonate therapy?

Factors predicting early fracture or bone loss on bisphosphonate therapy are not well defined. We studied 1588 patients over the age of 50 yr who were started on cyclic etidronate (1119) or alendronate (469) in the CANDOO (Canadian Database for Osteoporosis and Osteopenia Patients) Study. Incident fracture within 2 yr of starting therapy occurred in 31 patients and was independently predicted by a previous history of nonvertebral fracture (odds ratio [OR], 2.98, 95% confidence interval [CI], 1.30, 6.83, p = 0.010). Two hundred and fifty-seven patients lost >/=3% bone mass at the hip or spine (early bone loss) while on bisphosphonate therapy. Protection from early bone loss was most strongly independently predicted by treatment with alendronate with no previous history of etidronate use (OR, 0.29, CI, 0.13, 0.62, p = 0.002). In conclusion, early fracture on bisphosphonate therapy is most strongly predicted by a previous history of fracture and early bone loss is most strongly predicted by the potency of the prescribed bisphosphonate.

Intermittent intravenous administration of the bisphosphonate ibandronate prevents bone loss and maintains bone strength and quality in ovariectomized cynomolgus monkeys

Using a clinically relevant regimen, this study investigated the effects of treatment with ibandronate, a highly potent nitrogen-containing bisphosphonate, on bone loss, biochemical markers of bone turnover, densitometry, histomorphometry, biomechanical properties, and bone concentration in aged ovariectomized monkeys. Sixty-six female cynomolgus monkeys, aged 9 years and older, were ovariectomized (OVX) or sham operated. Intravenous (iv) bolus injections of ibandronate at 10, 30, or 150 microg/kg or placebo were administered at 30-day intervals (corresponding to intervals of 3 months in humans), starting at OVX, for 16 months. OVX significantly decreased bone mass at the lumbar spine, proximal femur, femoral neck, and radius and increased bone turnover in a time-dependent manner, as assessed by dual energy X-ray absorptiometry, peripheral quantitative computed tomography, or histomorphometry. Ibandronate iv bolus injections administered at 30 microg/kg every 30 days prevented osteopenia induced by estrogen depletion. OVX-induced increases in bone turnover (as determined by activation frequency, bone formation rate, and biochemical markers of bone turnover, including urinary N-telopeptide and deoxypyridinoline excretion and serum values for osteocalcin and bone-specific alkaline phosphatase) were suppressed on treatment, and bone mass, architecture, and strength were preserved at clinically relevant sites. Treatment with high-dose (150 microg/kg/dose) iv bolus injections of ibandronate further increased bone mass and improved bone strength at both the spine and femoral neck, without adversely affecting bone quality. In contrast, treatment with a 10 microg/kg/dose only partially prevented the OVX-induced effects. These data support the potential for the long-term administration of ibandronate by intermittent iv bolus injections in humans to prevent osteoporosis and improve bone quality at clinically relevant sites.

Severe osteopenia in a young boy with Kostmann's congenital neutropenia treated with granulocyte colony-stimulating factor: suggested therapeutic approach

Kostmann's syndrome is a congenital disorder that causes an impairment of myeloid differentiation in the bone marrow characterized by severe neutropenia, which can be treated with recombinant human granulocyte colony-stimulating factor (G-CSF). We present the case of a 13-year-old boy with Kostmann's syndrome who was treated with recombinant human G-CSF from age 3.5 years. His growth and development was normal, although complicated by intermittent infections. Bone mineral density (BMD) measurement revealed severe osteopenia at the spine and hips (lumbar spine BMD 0.486 g/cm(2); Z score -3.6), and he was referred to the Endocrine Service. Relevant laboratory evaluation showed a pretreatment ionized calcium level at the upper limit of normal (1.28 mmol/L; range: 1.13-1.32 mmol/L), suppressed intact parathyroid hormone (iPTH) level (12 pg/mL; range: 10-65 pg/mL), and a low 1,25-dihydroxy vitamin D level (21 pg/mL; range: 24-65 pg/mL). He had evidence of increased bone turnover evidenced by elevated urinary deoxypyridinoline (DPD) cross-links (46.9 nmol/mmol creatinine; range: 2-34 nmol/mmol creatinine) and a simultaneous increase in markers of bone formation with elevated osteocalcin level (200 ng/mL; normal: 20-80 ng/mL) and alkaline phosphatase level (236 IU/mL; normal: 38-126 IU/mL). Because of clinical concern for his skeletal health, bisphosphonate therapy with intravenous pamidronate was initiated. One month after treatment, the iPTH and DPD cross-links were in the normal range (54 pg/mL and 17.7 nmol/mmol creatinine, respectively) and the 1,25-dihydroxy vitamin D level was elevated (111 pg/mL). Four months after treatment, there was a striking increase in BMD at the lumbar spine (+30.86%), femoral necks (left, +20.02%; right, +17.98%), and total hips (left, +18.40%; right, +15.94%). Seven months after bisphosphonate therapy, his biochemical parameters showed a return toward pretreatment levels with increasing urinary DPD cross-links (28.7 nmol/mmol creatinine) and decreasing iPTH (26 pg/mL). However, the BMD continued to increase (8 months posttreatment), but the magnitude of the increment was attenuated (lumbar-spine, +4.8%; left total hip, +1.2% and right total hip +2.4%), relative to BMD at 4 months. Eight months after the initial treatment, his iPTH was suppressed at 14 pg/mL and he again received pamidronate (at a lower dose); 3 months later, he had an additional increase in BMD (lumbar spine +7.4%, left total hip +3.9%, right total hip +2.7%), relative to the previous study. We hypothesize that prolonged administration of G-CSF as treatment for Kostmann's syndrome is associated with increased bone resorption, mediated by osteoclast activation and leading to bone loss. In children, the resulting osteopenia can be successfully managed with antisreorptive bisphosphonate therapy with significant improvement in bone density. Measurements of biochemical parameters of bone turnover can be used to monitor the magnitude and duration of the therapeutic response and the need for BMD reassessment and, perhaps, retreatment.

Expanding the role of the orthopaedic surgeon in the treatment of osteoporosis

Osteoporosis is an increasingly prevalent disease among the aging population, and osteoporotic features account for substantial morbidity, mortality, and healthcare costs associated with this disease. Because the disease is silent until a fracture occurs, the orthopaedic surgeon often may be the physician in the best position to establish the diagnosis and consider the initiation of appropriate treatment. Historically, osteoporosis has been underdiagnosed and treated, but new methods allow accurate diagnosis using bone densitometry, and a range of effective treatment options that can reduce fracture risk. Diagnosis and treatment of osteoporosis fits readily into an efficient algorithmic approach in the office practice of orthopaedics. Orthopaedic surgeons can play a major role in improving the treatment of osteoporosis and decreasing morbidity from this disease. In addition, this can augment the office practice of orthopaedics with a large yet relatively underserved patient population. Finally, densitometry services can provide modest supplemental revenue sources for an orthopaedic practice.

Novel drug delivery system to bone using acidic oligopeptide: pharmacokinetic characteristics and pharmacological potential

We synthesized fifteen oligopeptides consisting of Asp or Glu conjugated with a fluorescent probe, 9- fluorenylmethylchloroformate (Fmoc). In the in vitro binding assay to putative hydroxyapatite (HA), the affinities of these conjugates depended only on the number of amino acid residues, not on their optical characters (L or D) or their species (Asp or Glu). In an in vivo experiment involving a single i.v. injection of Fmoc-D-Asp oligopeptides into mice, peptides consisting of over six Asp residues were selectively distributed to the bone. Then, we synthesized estradiol-17 beta-succinate-(L-Asp)6 [E2-(L-Asp)6] and studied its pharmacokinetic characteristics and its antiosteoporotic effects on ovariectomized (OVX) mice. Although the distribution volume of E2-(L-Asp)6 was significantly smaller than that of E2, E2-(L-Asp)6 was selectively distributed in the bone after i.v. injection and gradually decreased during 7 days. E2-(L-Asp)6 effectively prevented OVX-induced bone loss, without altering the uterine weight, in the dosage range of 0.11 to 1.1 mumol/kg once a week, while E2 increased both the bone mineral density and uterine weight at 0.37 mumol/kg every third day. The results suggest that acidic oligopeptide may be useful for drug delivery to bone and E2-(L-Asp)6 is a good candidate as an anti-osteoporosis drug without the adverse side effects of E2.

Osteoporosis therapies for rheumatoid arthritis patients: minimizing gastrointestinal side effects

OBJECTIVE

This manuscript identifies characteristics that put people with rheumatoid arthritis (RA) at high risk for osteoporosis or gastrointestinal (GI) disturbances. The manuscript then reviews therapies available for osteoporosis in the United States and makes recommendations about choosing therapies that minimize GI adverse effects in RA patients at high risk for such events.

DATA SOURCES

References identified through MEDLINE, abstracts, and prescribing information for individual drugs.

DATA EXTRACTION

Characteristics that predispose patients to osteoporosis and GI problems were identified. Data on individual osteoporosis therapies were assessed by risk-benefit analysis and appropriateness for use in patients at risk for GI disturbances.

DATA SYNTHESIS

High risk of osteoporosis in people with RA is caused by disease activity, medication effects, physical inactivity, and standard risk factors such as postmenopausal status and increased age. Patients with RA are frequently at high GI risk if they are receiving nonsteroidal anti-inflammatory drugs or corticosteroids. Because of the high potential for erosive esophagitis and other upper GI disorders with alendronate, caution is warranted in prescribing alendronate to RA patients with high GI risk. In such patients, estrogen replacement therapy, selective estrogen receptor modulators, or calcitonin should be considered for treatment, and either estrogen replacement therapy or selective estrogen receptor modulators should be considered for osteoporosis prevention.

CONCLUSIONS

Assessment of GI risk is important in patients with RA and osteoporosis. Risk factors should be considered when choosing osteoporosis therapies.

An update on glucocorticoid-induced osteoporosis

In general, bone loss from glucocorticoid treatment occurs rapidly within the first 6 months of therapy. Glucocorticoids alter bone metabolism by multiple pathways; however, the bone loss is greatest in areas rich in trabecular bone. Preventive measures should be initiated early. It is the author's opinion that all subjects initiating treatment with prednisone at 7.5 mg or greater require calcium supplementation (diet plus supplement) at a dose of 1500 mg and vitamin D at a dose of 400 to 800 IU/d. If the patient is going to remain on this dose of glucocorticoid for more than 4 weeks, an antiresorptive agent should be started (e.g., estrogen, bisphosphonate, raloxifene). If a patient has established osteoporosis and is either initiating glucocorticoid therapy or is chronically treated with prednisone at 5 mg d or greater in addition to calcium and vitamin D supplementation, a potent antiresorptive agent (bisphosphonate) should be started. A bone mineral density measurement of either the lumbar spine or the hip may be helpful is assessing an individual's risk of osteoporosis, may improve compliance with treatment, and can be used to monitor the efficacy of the prescribed therapy. There is no reason to withhold treatment for glucocorticoid-induced bone loss until a bone mass measurement is taken, however. In motivated patients, a weight-bearing and resistance exercise program should be prescribed to help retain muscle strength and prevent depression. If hypercalciuria develops with glucocorticoid use, either thiazide diuretics or sodium restriction may be helpful. In patients who continue to lose bone or experience fracture's despite antiresorptive therapy while on glucocorticoids, bone-building anabolic agents (e.g., hPTH 1-34 or PTH 1-84) may be available someday soon.

Nonoperative management of hyperparathyroidism: present and future

Parathyroidectomy provides effective treatment for primary and secondary hyperparathyroidism with a predictable response of symptoms related to hypercalcemia and elevated parathyroid hormone. Calcium and vitamin D supplementation has reduced the need for parathyroidectomy in dialysis patients with secondary hyperparathyroidism. However, surgery continues to be the only effective treatment of primary hyperparathyroidism. Potential nonoperative treatments for hyperparathyroidism have included the use of estrogen replacement, bisphosphonates, and a new class of drugs known as calcimimetics. Hormone replacement therapy with estrogen has been reported to improve cortical bone density in postmenopausal women with asymptomatic or mildly symptomatic primary hyperparathyroidism. Calcimimetic agents are a new class of drugs that increase the sensitivity of the calcium receptor to ionized calcium. Initial studies have shown that calcimimetics can acutely lower parathyroid hormone levels in patients with primary and secondary hyperparathyroidism. These drugs are currently being evaluated in phase II clinical trials. Ultimately, these medical modalities will need to be compared to parathyroidectomy in randomized controlled clinical trials.

Biochemical response to treatment of bone hyperresorption in chronically critically ill patients

STUDY OBJECTIVE

The chronically critically ill (CCI) are a subgroup of critically ill patients who have survived an acute critical illness but remain profoundly debilitated and ventilator dependent. We have previously shown that CCI patients have a very high prevalence of bone hyperresorption. The objective of this present study was to determine the biochemical response of bone hyperresorption in CCI patients to treatment with either calcitriol alone or calcitriol and pamidronate.

DESIGN

Retrospective survey.

SETTING

Respiratory care step-down unit (RCU) at a tertiary-care teaching hospital.

PATIENTS

Fifty-five ventilator-dependent CCI patients transferred from ICUs within the same institution who had elevated urine N-telopeptide (NTx) levels at RCU admission, who were treated with either calcitriol alone (n = 44) or calcitriol and pamidronate (n = 11), and who had urine NTx levels remeasured following treatment.

INTERVENTION

None.

MEASUREMENTS AND RESULTS

Patients treated with calcitriol alone had a significant reduction in serum parathyroid hormone (PTH; 93+/-145 pg/mL vs 40+/-28 pg/mL; p = 0.02) but not in urinary NTx (187+/-146 nmol bone collagen equivalents [BCE]/mmol creatinine [Cr] vs. 178+/-123 nmol BCE/mmol Cr, p = 0.59). In contrast, patients treated with both calcitriol and pamidronate had a significant decrease in urine NTx at follow-up (329+/-238 to 100+/-85 nmol BCE/mmol Cr; p<0.01) but not in serum PTH (36+/-29 to 53+/-51 pg/mL; p = 0.44).

CONCLUSION

The bone hyperresorption of CCI patients is PTH independent and biochemically responds to treatment with calcitriol and pamidronate but not calcitriol alone.

Steroid-induced osteoporosis in systemic lupus erythematosus

The patient with SLE is at considerable risk of osteoporosis, because of the inflammatory disease itself, its consequences, and its treatments. Because of their extensive use, glucocorticoids are thought to be the most frequent cause of drug-related osteoporosis and may be responsible for much of the bone loss in lupus. This article focuses on the mechanisms of steroid-induced osteoporosis in SLE and outlines strategies for prevention and treatment.

Intermittent and continuous administration of the bisphosphonate ibandronate in ovariohysterectomized beagle dogs: effects on bone morphometry and mineral properties

Bisphosphonates have emerged as a valuable treatment for postmenopausal osteoporosis. Bisphosphonate treatment is usually accompanied by a 3-6% gain in bone mineral density (BMD) during the first year of treatment and by a decrease in bone turnover. Despite low bone turnover, BMD continues to increase slowly beyond the first year of treatment. There is evidence that bisphosphonates not only increase bone volume but also enhance secondary mineralization. The present study was conducted to address this issue and to compare the effects of continuous and intermittent bisphosphonate therapy on static and dynamic parameters of bone structure, formation, and resorption and on mineral properties of bone. Sixty dogs were ovariohysterectomized (OHX) and 10 animals were sham-operated (Sham). Four months after surgery, OHX dogs were divided in six groups (n = 10 each). They received for 1 year ibandronate daily (5 out of 7 days) at a dose of 0, 0.8, 1.2, 4.1, and 14 microg/kg/day or intermittently (65 microg/kg/day, 2 weeks on, 11 weeks off). Sham dogs received vehicle daily. At month 4, there was a significant decrease in bone volume in OHX animals (p < 0.05). Doses of ibandronate >/= 4.1 microg/kg/day stopped or completely reversed bone loss. Bone turnover (activation frequency) was significantly depressed in OHX dogs given ibandronate at the dose of 14 microg/kg/day. This was accompanied by significantly higher crystal size, a higher mineral-to-matrix ratio, and a more uniformly mineralized bone matrix than in control dogs. This finding lends support to the hypothesis that an increase in secondary mineralization plays a role in gain in BMD associated with bisphosphonate treatment. Moreover, intermittent and continuous therapies had a similar effect on bone volume. However, intermittent therapy was more sparing on bone turnover and bone mineral properties. Intermittent therapy could therefore represent an attractive alternative approach to continuous therapy.