Intravenous ibandronate injections given every three months: a new treatment option to prevent bone loss in postmenopausal women

Bisphosphonates Preserve Bone Mineral Density and Suppress Bone Turnover Markers in Early Menopausal Women: A Systematic Review and Meta-Analysis of Randomized Trials

Most women do not qualify for pharmacologic osteoporosis treatment until more than a decade after menopause, by which time they will have lost up to 30% of their bone mass and may have already sustained fractures. Short or intermittent courses of bisphosphonate therapy, initiated around the time of menopause, might prevent excessive bone loss and lower long-term fracture risk. We undertook a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the effects of nitrogen-containing bisphosphonates on fracture incidence, bone mineral density (BMD), and bone turnover markers in early menopausal women (ie, perimenopausal or <5 years postmenopausal) over ≥12 months. Medline, Embase, CENTRAL, and CINAHL were searched in July 2022. Risk of bias was evaluated using the Cochrane Risk of Bias 2 tool. Random effect meta-analysis was undertaken using RevMan v5.3. In total, 12 trials were included (n = 1722 women); five evaluated alendronate, three risedronate, three ibandronate, and one zoledronate. Four were at low risk of bias; eight raised some concerns. Fractures were infrequent in the three studies that reported them. Compared with placebo, bisphosphonates improved BMD over 12 months (mean percentage difference, 95% confidence interval [CI]) at the spine (4.32%, 95% CI, 3.10%-5.54%, p < 0.0001, n = 8 studies), the femoral neck (2.56%, 95% CI, 1.85%-3.27%, p = 0.001, n = 6 studies), and the total hip (1.22%, 95% CI 0.16%-2.28%, p = 0.002, n = 4 studies). Over treatment durations of 24 to 72 months, bisphosphonates improved BMD at the spine (5.81%, 95% CI 4.71%-6.91%, p < 0.0001, n = 8 studies), femoral neck (3.89%, 95% CI 2.73%-5.05%, p = 0.0001, n = 5 studies) and total hip (4.09%, 95% CI 2.81%-5.37%, p < 0.0001, n = 4 studies). Bisphosphonates reduced urinary N-telopeptide (-52.2%, 95% CI -60.3% to -44.2%, p < 0.00001, n = 3 studies) and bone-specific alkaline phosphatase (-34.2%, 95% CI -42.6% to -25.8%, p < 0.00001, n = 4 studies) more than placebo at 12 months. This systematic review and meta-analysis shows that bisphosphonates improve BMD and lower bone turnover markers in early menopause, warranting further investigation of these agents for osteoporosis prevention. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

Validation of the Surrogate Threshold Effect for Change in Bone Mineral Density as a Surrogate Endpoint for Fracture Outcomes: The FNIH-ASBMR SABRE Project

The surrogate threshold effect (STE) is defined as the minimum treatment effect on a surrogate that is reliably predictive of a treatment effect on the clinical outcome. It provides a framework for implementing a clinical trial with a surrogate endpoint. The aim of this study was to update our previous analysis by validating the STE for change in total hip (TH) BMD as a surrogate for fracture risk reduction; the novelty of this study was this validation. To do so, we used individual patient data from 61,415 participants in 16 RCTs that evaluated bisphosphonates (nine trials), selective estrogen receptor modulators (four trials), denosumab (one trial), odanacatib (one trial), and teriparatide (one trial) to estimate trial-specific treatment effects on TH BMD and all, vertebral, hip, and nonvertebral fractures. We then conducted a random effects meta-regression of the log relative fracture risk reduction against 24-month change in TH BMD, and computed the STE as the intersection of the upper 95% prediction limit of this regression with the line of no fracture reduction. We validated the STE by checking whether the number of fractures in each trial provided 80% power and determining what proportion of trials with BMD changes ≥ STE reported significant reductions in fracture risk. We applied this analysis to (i) the trials on which we estimated the STE; and (ii) trials on which we did not estimate the STE. We found that the STEs for all, vertebral, hip, and nonvertebral fractures were 1.83%, 1.42%, 3.18%, and 2.13%, respectively. Among trials used to estimate STE, 27 of 28 were adequately powered, showed BMD effects exceeding the STE, and showed significant reductions in fracture risk. Among the validation set of 11 trials, 10 met these criteria. Thus STE differs by fracture type and has been validated in trials not used to develop the approach. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Adjuvant drug-assisted bone healing: Part III - Further strategies for local and systemic modulation

In this third in a series of reviews on adjuvant drug-assisted bone healing, further approaches aiming at influencing the healing process are discussed. Local and systemic modulation of bone metabolism is pursued with use of a number of drugs with completely different indications, which are characterized by a pleiotropic spectrum of action. These include drugs used to treat lipid disorders (HMG-CoA reductase inhibitors), hypertension (ACE inhibitors), osteoporosis (bisphosphonates), cancer (proteasome inhibitors) and others. Potential applications to enhance bone healing are discussed.

Use of bone turnover markers in postmenopausal osteoporosis

Bone turnover comprises two processes: the removal of old bone (resorption) and the laying down of new bone (formation). N-terminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX-I) are markers of bone formation and resorption, respectively, that are recommended for clinical use. Bone turnover markers can be measured on several occasions in one individual with good precision. However, these markers are subject to several sources of variability, including feeding (resorption decreases) and recent fracture (all markers increase for several months). Bone turnover markers are not used for diagnosis of osteoporosis and do not improve prediction of bone loss or fracture within an individual. In untreated women, very high bone turnover marker concentrations suggest secondary causes of high bone turnover (eg, bone metastases or multiple myeloma). In people with osteoporosis, bone turnover markers might be useful to assess the response to anabolic and antiresorptive therapies, to assess compliance to therapy, or to indicate possible secondary osteoporosis. Much remains to be learnt about how bone turnover markers can be used to monitor the effect of stopping bisphosphonate therapy (eg, to identify a threshold above which restarting therapy should be considered). More studies are needed to investigate the use of bone turnover markers for assessment of the bone safety of new medications.

Ibandronate: its pharmacology and clinical efficacy in the management of tumor-induced hypercalcemia and metastatic bone disease

It is well accepted that tumor cells in the bone, especially from breast cancer, prostate cancer and multiple myeloma, can stimulate osteoclast formation and activity. Bisphosphonates are potent inhibitors of osteoclast-mediated normal and pathologic bone resorption. Besides their apoptotic and antiproliferative activity on osteoclasts, bisphosphonates can also exert similar effects on macrophages and tumor cells. Currently, it is unknown if this effect can be translated into clinical practice with regard to an effective adjuvant therapeutic regimen for high-risk patients with systemic recurrences following primary treatment of a given cancer. There are several new aspects that might extend the clinical use of ibandronate, a bisphosphate, in oncology: prevention of hypogonadal osteoporosis in men, palliative management of painful osseous metastases and adjuvant therapy of high-risk prostate cancer patients. Safety and tolerability are excellent for the oral and intravenous formulations, and ibandronate can even be safely applied in pre-existing renal insufficiency. The purpose of this review is to critically reflect the pharmacology and clinical efficacy of ibandronate in the management of tumor-induced hypercalcemia, osteoporosis and metastatic bone disease.

Ibandronate for prevention and treatment of glucocorticoid-induced osteoporosis in rabbits

The objective of this study is to evaluate the efficacy of ibandronate (IBN) in prevention and treatment of glucocorticoid-induced osteoporosis in rabbits. A total of 60 New Zealand white rabbits were randomly allocated into six groups. Twenty rabbits in the control group were injected with saline. Forty rabbits received dexamethasone (DX) treatment at a dose of 3 mg/kg twice weekly during the first 6 weeks, while 10 of these rabbits (group IBN&DX) were injected additionally with IBN at a dose of 2 mg/kg before DX treatment. At week 6, the rabbits from IBN&DX group, 10 rabbits from control group (group CNTR-1) and 10 rabbits treated with DX (group DX6) were killed. Half (10) of the remaining rabbits in DX group were continued for DX treatment at a dose of 3 mg/kg once weekly (group DX12), while the other half (10) rabbits (group DX&IBN) additionally received IBN injection (2 mg/kg) once before continuing DX treatment. The remaining rabbits (10) in an additional of control group (group CNTR-2) continuously received saline. At week 12, all rabbits were killed for bone biomechanical analysis and histological examination. At week 6, the analysis of bone biomechanical and histological results of group CNTR-1 and DX6 showed that GIOP rabbit models were successfully established. Compared with group DX6, bone volume/tissue volume (BV/TV), trabecular number (Tb.N) and trabecular thickness (Tb.Th) of lumbar spine in group IBN&DX were increased by 100, 45.74 and 40.55%, respectively (P < 0.01). Meanwhile, BV/TV and Tb.N of femoral neck were increased by 30.29 and 16.86%, respectively (P < 0.01). The maximum compressive load, the maximum bending stress and the maximum torque were increased by 24.19, 29.91 and 37.24%, respectively (P < 0.01). At week 12, in comparison of the results between group DX12 and group DX6, the histomorphometric and mechanical analysis demonstrated that prolonged DX treatment could lead to further loss of bone mass and strength. Compared with group DX12, BV/TV, Tb.N and Tb.Th of lumbar spine in group DX&IBN were increased by 73.34, 39.02 and 23.87%, respectively (P < 0.05), the parameters of femoral neck were increased by 88.75, 31.29 and 42.01%, respectively (P < 0.01), and the biomechanical parameters were increased by 54.36, 21.38 and 105.75%, respectively (P < 0.05). IBN could effectively prevent and treat high-dosing glucocorticoid-induced loss of bone mass and strength in rabbits.

The silent thief: diagnosis and management of osteoporosis

Osteoporosis causes approximately 1.5 million fractures every year in the United States. Not only can these fractures be painful and disfiguring but they may reduce a person's ability to lead an active life as well. Osteoporosis affects every bone in the body, but the most common places where fractures occur are the back, hips, and wrists. Because osteoporosis thins bones, weakening them and making them more susceptible to fractures, practitioners must understand the risk factors and the diagnosis and management of this very common problem. This article, geared toward advanced practice nurses, presents a summary of the latest diagnostic tests and medication treatments available and approved by the Food and Drug Administration for the management of osteoporosis.

Efficacy and safety of bazedoxifene, a novel selective estrogen receptor modulator for the prevention and treatment of postmenopausal osteoporosis

OBJECTIVE

Osteoporosis affects millions of individuals, particularly postmenopausal women, and imposes a severe burden on patients and the healthcare system. Several therapeutic options are commercially available for the prevention and treatment of osteoporosis, including bisphosphonates, hormone therapy, and the selective estrogen receptor modulator (SERM), raloxifene. Because each of these agents has its own individual risk-benefit profile, their use should be tailored to specific patient populations. While many agents are approved for osteoporosis, new therapies are needed that maximize efficacy outcomes and minimize safety concerns. Several new SERMs are being evaluated in an effort to achieve an ideal tissue selectivity profile, with beneficial effects on bone without negative effects on the endometrium and breast. Bazedoxifene is a novel SERM that was recently approved in the European Union and is undergoing regulatory review in the United States for the prevention and treatment of postmenopausal osteoporosis. This article reviews the clinical efficacy and safety data for bazedoxifene in postmenopausal women with or at risk for osteoporosis.

METHODS

The PubMed database and relevant congress abstract databases were searched to identify all pertinent literature on bazedoxifene for the prevention and/or treatment of postmenopausal osteoporosis.

RESULTS

In phase 3 clinical studies, bazedoxifene has demonstrated significant reduction in the risk of new vertebral fracture versus placebo and positive effects on bone mineral density and bone turnover. Moreover, in a subgroup analysis of women at high risk for fracture, bazedoxifene significantly reduced the risk of nonvertebral fracture versus both placebo and raloxifene. Bazedoxifene was generally safe and well-tolerated in women with and at risk for osteoporosis, with no evidence of endometrial or breast stimulation. Data inclusion for this review article was limited by what was available in the public domain.

CONCLUSION

The available clinical data suggest that bazedoxifene may offer a favorable risk-benefit profile for the prevention and treatment of postmenopausal osteoporosis.

Infusion of ibandronate once every 3 months effectively decreases bone resorption markers and increases bone mineral density in Chinese postmenopausal osteoporotic women: a 1-year study

The efficacy and safety of intravenous ibandronate were evaluated in postmenopausal osteoporosis women in China. In this multicenter, positive drug-controlled study, 158 postmenopausal osteoporotic women were randomized to receive 2 mg ibandronate given intravenously once every 3 months or 70 mg alendronate given orally once per week. All women also received supplemental calcium (500 mg) and vitamin D (200 IU) daily. One hundred fifty-one patients completed the 1-year study. Ibandronate produced mean increases in bone mineral density (BMD) by 4.27% at the lumbar spine, 3.48% at the femoral neck, and 2.03% at the trochanter. Mean increases in BMD by 4.24% at the lumbar spine, 2.72% at the femoral neck, and 2.99% at the trochanter were observed in the alendronate group. No significant difference was found between the two groups in BMD in all sites measured. Significant decreases in serum c-telopeptide of type I collagen (CTX) and alkaline phosphatase (ALP) were found in the two groups after 1 and 3 months of treatment, respectively; these serum CTX and ALP levels were then maintained at the decreased levels throughout the study period (12 months). No changes of stature were found in the patients of the two groups. Adverse events were similar in the two groups, except more mild muscle pain was observed in the first month after infusion of ibandronate than with oral alendronate (P < 0.001). The results observed in Chinese patients may support the observation that intravenous ibandronate significantly reduced bone resorption and increased BMD with good tolerance in Chinese postmenopausal osteoporotic women. Use of intravenous ibandronate possibly could potentially improve compliance as compared with other oral bisphosphonates because it may avoid the peptic side effects of oral bisphosphonate.

Intravenous bisphosphonates for postmenopausal osteoporosis

Numerous clinical studies have shown bisphoshonates (BPs) to be useful and cost-effective options for the fractures prevention and postmenopausal bone loss. The use of oral bisphoshonates is an established option for managment of osteoporosis in postmenopausal women, but many of them complaint from gastrointestinal side effect or frequently dosed oral regimens. To improve upon the suboptimal therapeutic compliance in postmenopausal women, newer, longer-acting intravenous formulations of BPs has been approved for intermittent administration in postmenopausal women. These preparations would become an option for patients who can not tolerate oral BPs or it was ineffective in increasing their bone density.This article proposed to review effectiveness and tolerability of intravenous BPs in postmenopausal women with osteoporosis.

Medical treatment of osteoporosis in the elderly

Fractures, mostly of the hip and pelvis, wrist, and sometimes of the vertebra, account for nearly half of emergency department treatments for elderly individuals seen because of a fall. Bone density measurements show that more than half of these patients have osteoporosis. The notion that it is too late to start treatment in a late stage of the disease forms a barrier to treatment. The aim of this article is to evaluate the effectiveness of therapeutic options for osteoporosis in the elderly, with a view to reducing the incidence of fractures. Although most studies of fracture reduction with medical treatment were not designed for the "geriatric" population, the average age of participants in most clinical trials was about 70 years. Nowadays, clinicians can choose from several effective treatments for the prevention of osteoporotic fractures in high-risk postmenopausal women. Data on the antifracture potential of calcium/vitamin D, raloxifene, bisphosphonates, strontium ralenate, and parathyroid hormone are now available. In all major studies patients also received calcium and vitamin D supplements. Bisphosphonates and strontium ranelate are good choices for first- or second-line treatment, while for the time being parathyroid hormone should only be used for the second-line treatment of osteoporosis in the elderly. The ease of use of bisphosphonates, with once weekly, once monthly, or intravenous administration, may be advantageous for elderly patients already taking multiple medications.

New and emerging treatments for osteoporosis

A variety of new treatments for osteoporosis have become available within the last several years, and a number of emerging treatments remain in late clinical stage development. New and emerging treatments include more potent members, or more convenient formulations, of existing classes of therapy, but a number of the emerging treatments are first-generation compounds addressing specific therapeutic targets based on recent advances in understanding of basic bone biology. These new and emerging treatments include agents with anticatabolic effects, compounds with anabolic effects, and one agent possibly containing both anticatabolic and anabolic effects. The increasing variety of new and emerging treatments increases the possibility that effective therapy will be targeted to the specific needs of the individual patient.

Management of osteoporosis among home health and long-term care patients with a prior fracture

Osteoporosis is a growing health concern as the number of senior adults continues to increase worldwide. Falls and fractures are very common among frail older adults requiring home health and long-term care. Preventative strategies for reducing falls have been identified and many therapies (both prescription and nonprescription) with proven efficacy for reducing fracture risk are available. However, many practitioners overlook the fact that a fragility fracture is diagnostic for osteoporosis even without knowledge of bone mineral density testing. As a result, osteoporosis is infrequently diagnosed and treated in the elderly after a fracture. Based on existing literature, we have developed an algorithm for the assessment and treatment of osteoporosis among persons with known prior fracture(s) living in long-term care facilities or receiving home health care based on the data available in the literature.

Ibandronate: a review of its use in the management of postmenopausal osteoporosis

Ibandronate (ibandronic acid; Bonviva, Boniva), a nitrogen-containing bisphosphonate available in once-monthly oral and quarterly intravenous formulations for intermittent administration, has been approved for the treatment of osteoporosis in postmenopausal women in the EU, the US and many other countries worldwide. The once-monthly oral formulation has also been approved for the prevention of postmenopausal osteoporosis in the US. Ibandronate is an effective and generally well tolerated bisphosphonate that offers an alternative to other bisphosphonates as a first-line treatment for postmenopausal osteoporosis. It occupies a similar position with respect to the prevention of osteoporosis in postmenopausal women at risk for the disease. The once-monthly oral and quarterly intravenous dosage regimens have the potential to improve treatment adherence and persistence, and hence clinical outcomes, compared with more frequently administered oral bisphosphonates. Intravenous ibandronate may be particularly useful for postmenopausal osteoporotic women who are noncompliant with, or are unable to tolerate or receive, oral bisphosphonates. Thus, intermittent ibandronate extends the range of pharmacological therapies for the treatment and prevention of postmenopausal osteoporosis.

[Treatment of osteoporosis in the elderly: what is the evidence?]

Many older people, especially women, and their doctors still see osteoporosis as part of the natural course of ageing instead of as a preventable or treatable disorder. Height loss, hyperkyphosis, back pain, and fractures are accepted as consequences of ageing. The notion that it is too late to start treatment in a late stage of the disease forms another barrier to treatment. Although most studies of fracture reduction with medical treatment were not designed for the "geriatric" population, the average age of participants in most clinical trials was about 70 years. In all major studies patients also received calcium and vitamin D supplements. Nowadays, clinicians can choose from several effective treatments for the prevention of osteoporotic fractures in high-risk postmenopausal women. Data on the anti-fracture potential of calcium/vitamin D, raloxifene, bisphosphonates, strontium ralenate, and parathyroid hormone are now available. Bisphosphonates and strontium ralenate are good choices for first- or second-line treatment, while for the time being parathyroid hormone should only be used for the second-line treatment of osteoporosis in the elderly.

Quarterly intravenous ibandronate for postmenopausal osteoporosis

Osteoporosis is under-recognized and undertreated among postmenopausal women. Nitrogen-containing bisphosphonates are its first-line pharmacotherapy. Oral bisphosphonate treatment requires stringent dosing guidelines to minimize gastrointestinal irritation and enhance absorption. This paper reviews the efficacy, safety and tolerability of quarterly intravenous ibandronate 3 mg injection, approved in 2006 in the USA and Europe. Quarterly intravenous ibandronate injection has shown superior efficacy to daily oral ibandronate for bone mineral density increase and fracture prevention. No drug-related serious atrial fibrillation events have been reported with intravenous ibandronate. The regimen has a favorable renal safety profile. Quarterly intravenous ibandronate is administered as a simple 15-30-s intravenous injection in a physician's office and provides a beneficial option for patients who are unable to tolerate oral administration.

Quarterly intravenous injection of ibandronate to treat osteoporosis in postmenopausal women

Osteoporosis is a chronic condition that generally requires long-term therapy for fracture risk reduction to become apparent. Although the bisphosphonates have made a major contribution to how clinicians manage osteoporosis, compliance with therapy has generally been less in the real-world setting than seen in clinical trials. Less-frequently administered dosage regimens or nonoral routes may enhance compliance and so maximize the therapeutic benefit of bisphosphonates. Ibandronate is a nitrogen-containing bisphosphonate, whose high potency allows it to be administered orally or intravenously with extended dosing intervals. This paper will review the role of intravenous ibandronate in the treatment of postmenopausal osteoporosis.

Long dosing intervals in the treatment of postmenopausal osteoporosis

BACKGROUND

Osteoporosis is a common disease associated with diminished bone strength and increased risk of fracture. With the aging of the population, the number of people with osteoporosis, particularly postmenopausal women, is expected to increase. There are excellent tools for diagnosing osteoporosis and widely available treatments that are safe and effective. Nevertheless, osteoporosis is underdiagnosed and undertreated. Even among those who are diagnosed and treated, widespread nonadherence with treatment regimens undermines the efficacy of osteoporosis therapy.

PURPOSE

To examine the pharmacological options for the treatment of postmenopausal osteoporosis and the influence of extended dosing intervals upon outcomes, medication adherence, and patient preference.

METHODS

A Medline and Cochrane Review database search was conducted for appropriate clinical trials, meta-analyses, and systematic reviews published between 1987 and 2007.

FINDINGS

The causes of nonadherence include poor understanding of the consequences of a silent disease, concern regarding potential side-effects of medications, the inconvenience associated with administration of some osteoporosis medications, and medication costs. The recent development of effective oral and injectable osteoporosis medications that can be given with long dosing intervals may improve patient adherence. Less frequent dosing lessens the inconvenience of administration, and dosing by injection assures that the medication is 100% bioavailable. Osteoporosis patients have shown a preference for monthly bisphosphonate dosing compared with weekly dosing.

CONCLUSION

Enhanced adherence with new dosing regimens can be expected to improve treatment efficacy, reduce fracture risk, and lessen the burden of osteoporosis on patients and society. Further study is required to fully elucidate the relationship between extended dosing, adherence, and positive outcomes.

Update on Osteoporosis Management in Long-term Care: Focus on Bisphosphonates

Osteoporotic fractures are potentially devastating and associated with high morbidity and substantial economic burden. Residents of long-term care facilities are at greater risk of osteoporosis and its related fractures than those living in the community, yet osteoporosis is underdiagnosed and undertreated in these settings. Bisphosphonates are approved by the Food and Drug Administration for the treatment and prevention of osteoporosis in postmenopausal women. As a class, bisphosphonates have been shown to increase bone mineral density, decrease the markers of bone resorption, and reduce the risk of osteoporotic fractures. The 3 approved bisphosphonates are alendronate, risedronate, and ibandronate. Alendronate and risedronate are dosed daily or weekly and ibandronate, the most recently approved bisphosphonate, has been approved for monthly oral dosing or as an intravenous formulation to be given intermittently (every 3 months). In addition, other products with different mechanisms of action are in the pharmaceutical pipeline and may offer additional management options.

Use of intravenous bisphosphonates in osteoporosis

Bisphosphonates, which are potent bone resorption inhibitors, currently are the mainstay of treatment for osteoporosis. Antifracture efficacy has been demonstrated for at least three nitrogen-containing bisphosphonates in oral formulations that are designed to be administered in weekly or monthly dosing regimens. Frequent reports of adverse events, primarily related to the upper gastrointestinal tract, and the strict dosing schedule necessary for oral bisphosphonate therapy are considered the major reasons for disappointing adherence to therapy. New intravenous formulations have been developed that allow dosing at very long intervals, thus avoiding the gastrointestinal complications associated with oral bisphosphonates and, it is hoped, improving compliance, particularly for patients who are intolerant of oral bisphosphonates or have contraindications to their use. This alternative approach holds promise for improved outcomes of osteoporosis treatment and ultimately for reduced health care costs related to caring for people with fragility fractures.

Tolerability of different dosing regimens of bisphosphonates for the treatment of osteoporosis and malignant bone disease

Bisphosphonates are the primary pharmacological agents used for the management of osteoporosis and hypercalcaemia of malignant bone disease. The efficacy of these agents in these two conditions has been demonstrated in many well designed trials published over the past 2 decades. The variety of bisphosphonates currently available to us provides a wide range of tolerability and dosing profiles thus necessitating a thorough comparison of the most recent oral and intravenous bisphosphonates to differentiate the clinical context in which they should be used. Despite the fact that bisphosphonates are generally well accepted, their tolerability is dependent on complications which encompass gastrointestinal (GI) and renal toxicity. Other adverse events include osteonecrosis of the jaw, arthralgias, flu-like symptoms and uveitis. Studies have shown that various dosing regimens are able to modulate these rates of toxicity. To maximise tolerability, the direction of future therapy will likely fall into a pattern of decreasing the frequency of administration of bisphosphonates, whether it is oral or intravenous formulations, thus improving patient adherence. To review the literature on different dosing regimens of various bisphosphonates and their associated tolerability, we searched MEDLINE for articles from 1975 to 2006. Oral bisphosphonates, in particular alendronate and risedronate, have been systematically evaluated with regards to GI toxicity. Overall tolerability with these oral formulations has found GI toxicity to be the primary adverse event of interest. Both alendronate and risedronate have been found to have similar rates of GI toxicity when compared with placebo. Mounting evidence has developed validating the use of intravenous ibandronate and zoledronic acid for the purpose of treating hypercalcaemia secondary to malignancy. Unique to all other bisphosphonates, ibandronate also has an oral form which has a similar GI-toxicity profile to placebo. In addition, no significant differences in renal toxicity have been observed between those receiving intravenous ibandronate compared with placebo. Because of its potency and mode of administration, zoledronic acid has been widely accepted for the treatment of hypercalcaemia secondary to malignancy. However, a decrease in renal function, albeit rare, remains a significant complication of zoledronic acid; therefore, regular renal monitoring is recommended.

Recent developments in bisphosphonate therapy

OBJECTIVE

To provide a review of current developments in bisphosphonates indicated for the treatment of several rheumatologic conditions, including postmenopausal and glucocorticoid-induced osteoporosis.

METHODS

This review summarizes the pathology, diagnosis, and treatment of both postmenopausal and glucocorticoid-induced osteoporosis and examines the results of current clinical trials of the newest oral and intravenous formulations of nitrogen-containing bisphosphonates. We discuss important adverse events, including upper gastrointestinal symptoms and osteonecrosis of the jaw. Additionally, we explore methods that may improve patient adherence to bisphosphonate therapy, which is currently suboptimal.

RESULTS

Clinical studies have shown that oral bisphosphonates are efficacious in increasing bone mineral density and reducing risk of fracture. Despite concerns of upper gastrointestinal irritation, most of the newer oral bisphosphonates display a safety profile similar to placebo. Many of the newest formulations offer patients a choice in both dosing frequency and method of administration (either oral or intravenous).

CONCLUSIONS

Nitrogen-containing bisphosphonates are important therapeutic options for the prevention and treatment of osteoporosis.

Advances in the management of corticosteroid-induced osteoporosis with bisphosphonates

Corticosteroids are widely used as anti-inflammatory and immunosuppressive agents to treat a variety of chronic conditions. Long-term (>1 year) corticosteroid use can lead to bone loss, and therefore, osteopenia or osteoporosis. Corticosteroid-induced osteoporosis (CIO) leads to increased bone fragility and subsequently fractures, which, in turn, lead to a loss of physical, emotional and social health for the patient and increased costs for healthcare providers. A wealth of data exists demonstrating the efficacy of the oral bisphosphonates, etidronate, alendronate and risedronate in increasing bone mineral density in patients with CIO or preventing bone loss in patients commencing corticosteroid therapy. Data regarding fracture prevention are less clear, as statistically significant reductions in the incidence of fractures have only been reported for patient subgroups or meta-analyses. However, many treatment guidelines recommend the use of oral bisphosphonates for the prevention and treatment of CIO. These guidelines are, however, not reflected in prescribing practice, and the majority of patients do not receive adequate concomitant therapy. This review summarizes the available data for bisphosphonates in CIO. Therapeutic adherence with oral bisphosphonates is an issue, with approximately 50% of patients discontinuing therapy within the first year. The primary reasons for this are poor gastrointestinal tolerability and the frequency with which complex dosing requirements must be followed. The inconvenience of taking daily or weekly bisphosphonate therapy is of particular importance in patients with CIO who may be regularly taking several other medications. Data obtained in studies with ibandronate indicate that bisphosphonate administration by rapid intravenous injection provides an effective, well-tolerated and practical alternative to current oral regimens in the management of patients with CIO.

Ibandronate, an experimental intravenous bisphosphonate for osteoporosis, bone metastases, and hypercalcemia of malignancy

Ibandronate is an experimental intravenous bisphosphonate under study for the prevention or treatment of osteoporosis and skeletal complications of bone metastases, as well as hypercalcemia of malignancy. To review the data on this drug, PubMed/MEDLINE was searched for pertinent studies in English; data from January 1986-October 2005 were reviewed. In preclinical studies, ibandronate was an extremely potent bisphosphonate compared with its predecessors and was active in all animal models of human postmenopausal and corticosteroid-associated osteoporosis. Similar to other bisphosphonates, ibandronate exhibits antitumor activity and prevents or reduces bone metastases. Forty to fifty percent of the dose is bound to bone; renal clearance of unchanged drug accounts for 70% of total body clearance. Early clinical trials demonstrated efficacy and tolerability of intravenous ibandronate in the prevention or treatment of postmenopausal and corticosteroid-associated osteoporosis when administered once every 3 months. Intravenous ibandronate also reduces skeletal complications of bone metastases, including pain, although the cumulative dose used is much higher than that used in osteoporosis, as the drug is administered every 3-4 weeks. Single doses of intravenous ibandronate are probably also effective in the treatment of hypercalcemia of malignancy. The major tolerability issue with intravenous bisphosphonates is renal safety, thus the drugs generally require infusion (e.g., 0.25 hr for zoledronic acid, 2-24 hrs for pamidronate). However, intravenous ibandronate can be administered by bolus injection over a few minutes without an elevated risk of nephrotoxicity. The experimental intravenous dosage is 2 mg every 3 months for treatment or prevention of osteoporosis, and 2-6 mg every 3-4 weeks or in a single dose for treatment of bone metastases or hypercalcemia of malignancy, respectively. Ibandronate can be used in the presence of severe renal impairment with proper dosage adjustment. The drug will be an interesting addition to the available drugs for osteoporosis, bone metastases, and hypercalcemia of malignancy. Studies of intravenous ibandronate as an adjunctive treatment for cancers that tend to metastasize to bone are under way. Whether intravenous ibandronate will be a therapeutic advance is best answered by randomized, controlled trials. These are ongoing and should provide data with which to make better-informed choices concerning intravenous bisphosphonates.

Ibandronate Intravenous

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Once-monthly Ibandronate for postmenopausal Osteoporosis: Review of a new dosing regimen

BACKGROUND

Ibandronate, a nitrogen-containing bisphosphonate, was approved by the US Food and Drug Administration (FDA) in May 2003 as a daily oral regimen for the treatment and prevention of post-menopausal osteoporosis. In March 2005, the FDA approved once-monthly dosing with ibandronate for the same indications.

OBJECTIVE

The purpose of this article was to review the efficacy and tolerability of ibandronate 150 mg once monthly in the treatment and prevention of post-menopausal osteoporosis.

METHODS

A search of MEDLINE (1966-September 2005) and International Pharmaceutical Abstracts (1971-September 2005) for articles relating to the efficacy and tolerability of once-monthly ibandronate in the treatment of postmenopausal osteoporosis was conducted using the terms ibandronate and ibandronic acid. Additional searches were conducted to identify publications relevant to compliance and pharmacoeconomic considerations using the terms bispbospbonate, compliance, cost, and pharmacoeconomics. The reference lists of identified articles and presentations from recent scientific meetings also were reviewed. Selected safety information from the manufacturer was incorporated.

RESULTS

Ibandronate 2.5 mg/d and intermittent ibandronate (20 mg QOD for 12 doses every 3 months) have been shown to effectively reduce the incidence of vertebral fractures; after 3 years of therapy in a placebo-controlled clinical trial, the relative risk reductions for new vertebral fractures with daily and intermittent ibandronate were 62% and 50%, respectively (both, P<0.001 vs placebo). Once-monthly ibandronate has been evaluated in 2 clinical trials: a Phase I dose-ranging trial in 144 healthy postmenopausal women and a Phase III noninferiority trial in 1609 women with postmenopausal osteoporosis who were randomized to receive ibandronate 2.5 mg/d or 1 of 3 monthly ibandronate regimens: 50/50 mg (50 mg given on 2 consecutive days) once monthly; 100 mg once monthly; and 150 mg once monthly. The primary end point of the Phase III trial was the change from baseline in lumbar spine bone mineral density (BMD). After 1 year of therapy, patients who received ibandronate 150 mg once monthly had a significantly greater increase from baseline in lumbar spine BMD compared with those who received ibandronate 2.5 mg/d (4.9% vs 3.9%, respectively; P=0.002). The overall adverse-event profile was similar between the daily and monthly regimens. Drug-related adverse events were reported in 32.4% of patients receiving ibandronate 2.5 mg/d and 36.9% of patients receiving ibandronate 150 mg monthly. Upper gastrointestinal adverse events occurred in a respective 22.8% and 22.5% of the 2 groups. After 1 year of therapy, patients receiving ibandronate 150 mg monthly reported more flulike symptoms (8.3%) compared with those receiving ibandronate 2.5 mg/d (2.8%). In a crossover study comparing preference for and convenience of monthly ibandronate and weekly alendronate in 342 ambulatory women with postmenopausal osteoporosis, significantly more patients preferred the monthly ibandronate regimen to the weekly alendronate regimen (71.4% vs 28.5%, respectively; P<0.001).

CONCLUSION

Once-monthly ibandronate is an effective and well-tolerated treatment option for postmenopausal osteoporosis.

Ibandronate: the evolution of a once-a-month oral therapy for postmenopausal osteoporosis

Bisphosphonates have been shown to be highly effective in preventing and treating postmenopausal osteoporosis (PMO) and the associated risk of fracture. However, poor adherence with bisphosphonate therapies for PMO results in a high incidence of otherwise preventable fractures. The chronicity of this condition requires long-term treatment, but fewer than one in two women remains on daily bisphosphonate therapy for 1 yr. A good way to reduce the risk of osteoporotic fractures is through development of equally efficacious formulations with more convenient dosing regimens. Weekly formulations of bisphosphonates have been introduced that demonstrate comparable efficacy to daily formulations with slightly improved adherence. Recently, a new formulation utilizing a third-generation nitrogen-containing bisphosphonate--ibandronate--has been approved with a monthly dosing regimen. The pharmacokinetics and high potency of ibandronate, similar with other bisphosphonates, facilitate lower mg doses and longer-interval dosing frequencies with similar efficacy and enhanced tolerability. Preclinical studies and clinical trials have consistently demonstrated that it is the total cumulative dose of ibandronate that determines efficacy. The convenience of once-monthly dosing may ultimately improve adherence and clinical outcomes among the growing population of postmenopausal women at risk of osteoporosis.

Intravenous Ibandronate

Ibandronate (ibandronic acid) is a potent nitrogen-containing bisphosphonate that inhibits osteoclast-mediated bone resorption in women with postmenopausal osteoporosis. Recently, an intravenous (IV) formulation of ibandronate for intermittent injection, which circumvents the fasting and posture requirements associated with administration of oral bisphosphonates, was approved for use in this patient population. In initial placebo-controlled studies of 1 year's duration, IV ibandronate (< or =2mg once every 3 months) increased lumbar spine bone mineral density (BMD) and reduced levels of biochemical markers of bone turnover in a dose-dependent manner. Dosages < or =1mg every 3 months were found to be suboptimal in terms of fracture prevention in a 3-year trial. Subsequently, the large randomised, double-blind, noninferiority DIVA trial showed that, in terms of increasing lumbar spine BMD (primary endpoint), IV ibandronate 3mg once every 3 months and 2mg once every 2 months for 1 year were noninferior and also superior to oral ibandronate 2.5mg once daily, a regimen with proven antifracture efficacy. Median reductions from baseline in biochemical markers of bone turnover were similar for the IV and oral regimens. IV ibandronate was generally well tolerated in clinical trials. Treatment-related adverse events included musculoskeletal events and transient influenza-like symptoms, the latter mainly associated with the first dose.

Effective and rapid treatment of painful localized transient osteoporosis (bone marrow edema) with intravenous ibandronate

Localized transient osteoporosis (LTO; bone marrow edema syndrome) is a rare disorder of generally unknown etiology that is characterized by acute onset of disabling bone pain. Treatment options are currently limited and largely ineffective. The locally increased bone turnover and low bone mineral density (BMD) typical of LTO indicate a potential role for bisphosphonate therapy. Ibandronate, a potent nitrogen-containing bisphosphonate, has proven efficacy in the management of postmenopausal osteoporosis and corticosteroid-induced osteoporosis when administered as a convenient intermittent intravenous (i.v.) injection with a between-dose interval of 2 or 3 months. In a study of 12 patients with LTO, ibandronate was administered as an initial 4-mg i.v. dose with a second, optional injection of 2 mg at 3 months. Daily calcium and vitamin D supplements were provided. Pain was measured at baseline and at 1, 2, 3, and 6 months using a visual analog scale (VAS) of 1-10, and BMD was measured at baseline and 6 months. I.v. ibandronate provided rapid and substantial pain relief. The mean (SD) VAS score decreased from 8.4 (1.3) at baseline to 0.5 (0.7) at 6 months, at which time seven patients had achieved complete pain relief. At 6 months, mean lumbar spine BMD had increased by 4.0% (range -0.8 to 7.7%) in the overall population. I.v. ibandronate injection affords advantages over currently available oral and i.v. bisphosphonates and thus offers a promising therapeutic advance in the treatment of LTO.

Oral ibandronate: a less frequently administered therapeutic option for postmenopausal osteoporosis

Osteoporosis is a severe condition, associated with significant disability as a result of fragility fractures and increased mortality. Oral bisphosphonates effectively reduce the risk of osteoporotic fracture and are generally well tolerated. Unfortunately, patient outcomes are often compromised by suboptimal therapeutic adherence. In other disease areas, reduced dosing frequency has been shown to improve therapeutic adherence. A positive impact for adherence has been observed with a reduction in the bisphosphonate dosing frequency from daily to weekly. However, overall adherence remains suboptimal. Ibandronate is a potent nitrogen-containing bisphosphonate specifically designed for less frequent than weekly administration, without compromise for efficacy or tolerability. This article reviews the pharmacology, efficacy and tolerability of oral ibandronate when administered with extended dosing intervals in postmenopausal osteoporosis.

Biological properties and mechanism of action of ibandronate: application to the treatment of osteoporosis

Bisphosphonates, with their proven efficacy and safety, are the most commonly prescribed treatment for women with postmenopausal osteoporosis; however, optimal efficacy is often not achieved due to poor patient adherence to medication. Poor adherence leads to an increased risk of fracture, which itself results in morbidity, elevated healthcare costs and potentially, mortality. Although weekly rather than daily dosing of bisphosphonates has improved adherence, there remains a significant problem, and dosing less frequently than weekly has been suggested as a possible means for further improving adherence. Ibandronate is a new bisphosphonate that has a specific structure and set of characteristics that enable less frequent dosing than currently available bisphosphonates. This review provides details of the general structural features of all bisphosphonates and how these are understood to contribute to their functions in osteoporosis treatment. From this, the unique structure of ibandronate is described, along with how this translates into the high antiresorptive potency, favorable bone-binding, persistence in bone, and good tolerability that permits less frequent dosing. Finally, the clinical evidence for ibandronate is briefly presented, demonstrating the viability of less frequent dosing, with its potential benefits for patient convenience and adherence to therapy.

Analytical methods for the quantification of ibandronate in body fluids and bone

The accurate determination of bisphosphonate levels in bone and biological fluids is important in both clinical and pharmacological/toxicological studies. Ibandronate is a potent nitrogen-containing bisphosphonate containing a tertiary amine group, which does not easily form chromophore derivatives that can be detected by UV light or fluorescence emissions. The current report describes the methodology and validation of a GC-MS assay for ibandronate in serum/plasma and urine, a similar, modified GC-MS method for measurement of bone ibandronate levels, and an ELISA for ibandronate determination in serum/plasma. The range of quantification for the GC-MS was 1-100 ng/ml and 2-7500 ng/ml in plasma or serum and urine, respectively, and 50-1600 pg/ml (potentially 10-320 pg/ml depending on sample size) for the ELISA in plasma or serum. These assays were comparable. The practical application of the assays in preclinical and clinical studies is briefly reviewed.

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.

Bisfosfonatos intravenosos

Bisphosphonates possess a fundamental role in the treatment of bone metabolic diseases. Yet their main limitations are poor oral absorption and gastrointestinal side effects, mainly esophageal irritation. Indeed, oral administration is unpleasant for many patients, and it is difficult in bed-confined subjects. Therefore, intravenous administration of these agents can be very useful in several clinical scenarios, especially to improve the compliance. Recently, it has been showed that intravenous bisphosphonates are very useful to control hypercalcemia of malignancy, and to prevent bone complications related to metastases. Their use has also been analyzed in the prevention of bone disease after organ transplantation. Thus, their application to control Paget's disease of bone is well-known, and probably they could have an important role as antiresorptive agents in postmenopausal and steroidal osteoporosis. We present here a state of the art of the use of intravenous bisphosphonates for the aforementioned disorders.

New model for simulation of fracture repair in full-grown beagle dogs: model characterization and results from a long-term study with ibandronate

INTRODUCTION

Given that bisphosphonates reduce bone turnover, it is important to establish that their long-term administration does not impair bone quality. This paper describes a new model for simulation of fracture repair to evaluate several aspects of bone quality following long-term administration (34 or 36 weeks) of ibandronate in full-grown beagle dogs.

METHODS

The treatment schedule consisted of continuous daily subcutaneous administration of a pharmacologically active dose (1 microg/kg/day) and two cyclical intermittent regimens providing a similar total dose per animal at the end of the experiment. Seven or 8 weeks before study end, 10 holes were drilled in the left tibia and bone marrow ablation was performed in the ipsilateral femur. Serial measurements for blood biochemistry (osteocalcin and iso-alkaline phosphatase) and bone mineral density (BMD; whole body and L1-L7) by dual-energy X-ray absorptiometry (DEXA) were performed during the experiment. Bone quality was determined at the end of the experiment by assessing early and late stage defect healing and structural, cellular, and dynamic histomorphometry (femur, tibia, and lumbar vertebrae L3 and L4).

RESULTS

Healing of the drill hole defects, which simulate the first stage of fracture healing, was neither qualitatively nor quantitatively influenced by ibandronate. The same was true for the activation of cortical remodeling that occurs in the later stage of fracture healing, which started in Week 4 after surgery and declined after Week 8 in all groups. Additionally, no difference was found between the various regimens and the controls with respect to DEXA analyses, trabecular bone volume, cancellous bone tissue area, cancellous bone perimeter, osteoclast count, serum osteocalcin, or bone-specific alkaline phosphatase.

DISCUSSION

In conclusion, the presence of the first and second steps of fracture healing and the fact that the histological features closely resemble those of fracture repair validate the development and characterization of a new model for simulation of fracture repair. A long-term study with a therapeutically active dose of ibandronate shows that ibandronate does not impair BMD, bone structure, bone repair, coupling, and serum parameters for bone formation and turnover after long-term administration.

Optimizing Administration of Bisphosphonates in Women with Postmenopausal Osteoporosis

Bisphosphonates have been approved in the US as oral medication for the treatment of osteoporosis for about 10 years. Efficacy data exists for fracture reduction for the commonly used oral bisphosphonates but not for intravenous formulations. Based on the mechanism of action that appears to allow for longer intervals between doses, it has been possible to extend the treatment choices from the original more demanding daily oral dose to an array of options including oral weekly and more recently monthly treatment (so-called cyclical therapy) and intravenous treatment with various administration regimens. The possibility of treatment with an annual (or less frequent) intravenous administration with zoledronic acid exists. Compliance, adverse effects, and efficacy vary with each administration regimen.

Clinical Pharmacology of Potent New Bisphosphonates for Postmenopausal Osteoporosis

Bisphosphonates are potent inhibitors of bone resorption, used in most bone diseases associated with high bone resorption levels. Several bisphosphonates, developed to prevent and treat postmenopausal osteoporosis, increase bone mineral density and decrease biochemical markers of bone turnover, and more importantly, reduce fracture risk. Alendronate and risedronate have proven their efficacy to reduce vertebral and hip fracture risk among postmenopausal osteoporotic women, using daily regimens. Weekly intermittent schedules, however, are now most commonly prescribed, because they have shown pharmacologic equivalence to the daily regimen. Ibandronate has been the first bisphosphonate to demonstrate vertebral fracture risk reduction using an intermittent regimen. Studies using ibandronate as intravenous injections every 3 months are under way. Zoledronic acid may also be an attractive option for the treatment of postmenopausal osteoporosis if a large ongoing trial proves that a single annual injection of this compound allows osteoporotic fracture risk reduction.

Ibandronate: a clinical pharmacological and pharmacokinetic update

Ibandronate is a potent nitrogen-containing bisphosphonate. It has a strong affinity for bone mineral and potently inhibits osteoclast-mediated bone resorption. Ibandronate is effective for the treatment of hypercalcemia of malignancy, metastatic bone disease, postmenopausal osteoporosis, corticosteroid-induced osteoporosis, and Paget's disease. Oral ibandronate is rapidly absorbed (t(max) < 1 hour), with a low bioavailability (0.63%) that is further reduced (by up to 90%) in the presence of food. Ibandronate has a wide therapeutic index and is not metabolized and, therefore, has a low potential for drug interactions. Given its metabolic stability, ibandronate is eliminated from the blood by partitioning into bone (40%-50%) and through renal clearance (CL(R) approximately 60 mL/min). The CL(R) of ibandronate is linearly related to creatinine clearance. The sequestration of ibandronate in bone (V(D) > 90 L) results in a multiphasic elimination (t((1/2)) range approximately 10-60 hours), characterized by the slow release of ibandronate from the bone compartment. The potency of ibandronate and its sequestration into bone allow ibandronate to be developed as oral and intravenous injection formulations that can be administered with convenient extended between-dose intervals.

Nouveaux traitements de l'ostéoporose

New intermittent regimens with bisphosphonates such as oral ibandronate, and maybe annual intra-venous zoledronate, will be useful additions to the treatment of post-menopausal osteoporosis. Strontium ranelate is a new molecule that both inhibits bone resorption and stimulates bone formation, with proven efficacy to reduce fracture incidence. Teriparatide (1-34 fragment of parathyroid hormone), using daily subcutaneous injections, has also proven its efficacy to decrease vertebral and peripheral fracture risk in postmenopausal osteoporotic women. In the next five years, new SERMs and inhibitors of RANK-ligand might be new treatment options.

A semimechanistic and mechanistic population PK-PD model for biomarker response to ibandronate, a new bisphosphonate for the treatment of osteoporosis

AIMS

Ibandronate, a highly potent nitrogen-containing bisphosphonate, is the subject of an ongoing clinical development programme that aims to maximize the potential of simplified, less frequent oral and intravenous (i.v.) administration in osteoporosis. A modelling and simulation project was undertaken to characterize further the clinical pharmacology of ibandronate and identify convenient intermittent oral and i.v. regimens for clinical evaluation.

METHODS AND RESULTS

Using selected data from clinical studies involving 174 women with postmenopausal osteoporosis (PMO), a classical multicompartmental pharmacokinetic-pharmacodynamic (PK-PD) model was developed that accurately described the PK of i.v. ibandronate in plasma and urine and urinary excretion of the C-telopeptide of the alpha chain of type I collagen (uCTX), a sensitive biomarker of PD response to ibandronate. To reduce processing times, the classical PK-PD model was simplified using a "kinetics of drug action" or kinetic (K)-PD model (i.e. a dose-response model as opposed to a dose-concentration-response model). The performance of the K-PD model was evaluated by fitting data simulated with the PK-PD model under various dosing regimens. The simplified model produced a virtually indistinguishable fit of the data from that of the PK-PD model. The K-PD model was extended to consider the influence of supplemental therapy (calcium with or without vitamin D) on the PD response and validated by retrospectively simulating the uCTX response in a prior Phase III and Phase II/III study of i.v. ibandronate, given once every 3 months, in 3380 women with PMO. The observed median uCTX responses at the scheduled assessment points in the completed studies were within the distribution of the simulated responses. The K-PD model for i.v. ibandronate was extended further to allow simultaneous fitting of uCTX responses after i.v. and oral administration in 676 postmenopausal women with osteoporosis, and validated by retrospectively simulating the data observed in a Phase I study of oral daily ibandronate in 180 women with PMO. The K-PD model adequately described the uCTX response after oral dosing.

CONCLUSIONS

This validated K-PD model is currently being used to evaluate a range of novel intermittent oral and i.v. ibandronate regimens in an ongoing clinical development programme.

Intermittent ibandronate preserves bone quality and bone strength in the lumbar spine after 16 months of treatment in the ovariectomized cynomolgus monkey

The dose-dependent effect of ibandronate treatment on bone mass and architecture was assessed in a large animal study of OVX monkeys using microCT for quantitative bone morphometry and biomechanical testing for measures of bone strength. The study showed that intermittent ibandronate preserved lumbar spine bone quality and strength in these animals after 16 months of treatment.

INTRODUCTION

Ibandronate is a bisphosphonate, which is a class of compounds that, in pharmacologically active doses, not only suppresses bone resorption and turnover but also prevents loss of bone mass and strength in the ovariectomized (OVX) rat.

MATERIALS AND METHODS

We evaluated the effects of ibandronate on bone mass and architecture in the OVX cynomolgus macaque. Sixty-one adult female macaques were divided into five groups (N = 11-15): sham control, OVX control, and OVX low- (10 microg/kg), medium- (30 microg/kg), and high- (150 microg/kg) dose ibandronate. Treatment was administered by intravenous bolus injection every 30 days for 16 months starting at ovariectomy. This dosing schedule is equivalent to a 3-monthly dosing regimen in human subjects over 4 years. Animals were killed at the conclusion of the study, and excised bone specimens of the first lumbar vertebra (L1) were evaluated for quantitative bone densitometry, morphometry, and mechanical properties. Architectural parameters were assessed by microCT including direct 3D bone morphometry. A measure of specimen strength was obtained using destructive compression testing.

RESULTS AND CONCLUSIONS

A significant loss of bone mass and related changes in bone architecture after ovariectomy resulted in a reduction of whole bone strength as expressed by high correlations between architectural and mechanical properties. In this analysis, BMC was the best single predictor of whole bone strength (r2 = 67%). Nevertheless, including architectural indices in a multiple linear regression analysis increased that prediction to 88%. With respect to the treatment, the medium- and high-dose groups were not significantly different from the sham group for all bone mineral and structural parameters. Additionally, significant differences were seen for all measured parameters between the high-dose group and the OVX group, and for some parameters, between the medium-dose group and the OVX group. Intermittent ibandronate treatment effectively and dose-dependently prevented bone loss, architectural deterioration, and strength reduction in the lumbar spine of OVX monkeys.

Postmenopausal osteoporosis

The postmenopausal state is the most common underlying cause for osteoporosis and most of our understanding of the condition relates to this group. Recent evidence has suggested that hormone therapy may no longer have the pre-eminent place it once held but the same studies have also confirmed its antifracture efficacy. However, an increasing variety of alternative therapies are available for the postmenopausal woman. Furthermore, recent understanding of the mechanisms of bone loss after estrogen withdrawal, suggest that newer even better targeted therapies might be developed in the future.

Effective doses of ibandronate do not influence the 3-year progression of aortic calcification in elderly osteoporotic women

Animal experiments revealed conflicting results as to the impact of bisphosphonate treatment on atherosclerosis and related vascular calcification. The effect of long-term treatment with clinical doses of bisphosphonates on aortic calcification (AC) in an "at-risk" population of osteoporotic elderly women has not been assessed systematically. In the present analysis including 474 women (55-80 years) participating in two 3-year randomized, placebo-controlled clinical trials, we assessed the simultaneous impact of ibandronate given either orally (2.5 mg daily or 20 mg intermittently) or intravenously (0.5 mg or 1.0 mg IV every 3 months) on bone mass and AC. All women received calcium and vitamin D supplements. Bone mineral density (BMD) was measured at the lumbar spine and the total hip using dual-energy X-ray absorptiometry (DXA). Calcified deposits of the lumbar aorta (L1-L4) were visualized on lateral radiographs and severity was graded by a validated scoring system. Measurements were performed at baseline and at years 1, 2, and 3. At baseline, there was a significant inverse correlation between the severity of AC and BMD at the hip (r=-0.151, P=0.003), but not at the lumbar spine. The two oral doses and the 1.0 mg IV dose evoked statistically significant increases in both hip and spine BMD compared with placebo, whereas the effect of 0.5 mg was significant only at the hip (P<0.05). No differences in the yearly rate of progression or the 3-year change in AC was observed between the different intervention groups. Furthermore, there were no statistically significant correlations between the 3-year change in BMD and the simultaneous change in AC. These findings thus suggest that 3-year treatment with effective doses of ibandronate does not pose any cardiovascular risk in terms of altering vascular calcification.

Ibandronate in osteoporosis: preclinical data and rationale for intermittent dosing

Ibandronate is a highly potent, nitrogen-containing bisphosphonate. Unlike most other bisphosphonates, it is under clinical development for both oral and intravenous (i.v.) administration. Ibandronate can be used in convenient intermittent regimens that may optimize therapeutic outcome with enhanced compliance by patients. The preclinical pharmacokinetics (PK) and pharmacology of ibandronate have been extensively explored in a large preclinical development program involving various recommended animal models of human osteoporosis. These experimental studies of ibandronate indicate that the preclinical pharmacology and PK profile of ibandronate are broadly similar to those of other nitrogen-containing bisphosphonates. The efficacy of intermittent administration of subcutaneous (s.c.) and i.v. ibandronate has been demonstrated in four animal models (rat, dog, minipig, and monkey). Thus in rats, dogs, and monkeys with estrogen depletion, and in minipigs with glucocorticoid-induced bone loss, ibandronate administered s.c. or i.v. with extended intervals between doses reduces bone turnover, increases bone mineral density, and maintains bone quality in a dose-dependent manner. Furthermore, studies in rats and dogs comparing continuous and intermittent treatment schedules indicate similar efficacy when the same cumulative dose is applied over the duration of the study. These studies with ibandronate illustrate the concept that the total cumulative dose of bisphosphonate administered determines the response, independent of whether the dose is given daily or less frequently in a given time period. The efficacy of intermittent regimens has also been verified in models of secondary osteoporosis due to secondary hyperparathyroidism or immobilization (both in rats), or due to glucocorticoids in minipigs. Important factors for determining efficacy and the magnitude of response are the doses given, the length of the interval between doses, and the underlying bone turnover rate. The mechanisms underlying the remarkable efficacy of intermittent bisphosphonate dosing are not fully understood and further research is needed. Importantly, ibandronate is the only bisphosphonate so far proven to reduce the risk of vertebral fractures significantly with a between-dose interval >2 months, in a prospective clinical trial. Collectively, the preclinical studies on ibandronate have provided a sound basis for the design of the convenient regimens currently being examined in clinical trials.