Prolonged bisphosphonate release after treatment in women with osteoporosis. Relationship with bone turnover

Osteoporosis in premenopausal women

The development of osteoporosis and fractures in young premenopausal women is infrequent and is usually associated with secondary causes of osteoporosis. Therefore, it is recommendable to perform a clinical evaluation and a thorough laboratory study searching for possible causes of bone loss in these patients. Treatment depends on the cause of osteoporosis and the associated processes as well as the future gestational desire of the patient, all of which should be taken into account when evaluating the most adequate diagnostic and the therapeutic approach in these patients.

Bisphosphonate drug holidays in osteoporosis according to fracture risk profile

We analyzed the incidence of fractures and changes in bone mineral density and bone turnover markers in 264 patients who discontinued bisphosphonates. Fractures were recorded in 12.3%. Half were clinical vertebral fractures. We identified patients with a high-risk profile who should not discontinue treatment.

OBJECTIVE

The optimal length of bisphosphonate discontinuation is unknown, as is the type of patient who could benefit from this approach. The objectives of the study were to analyze, in clinical practice, the incidence of fractures and associated risk factors, changes in bone mineral density (BMD) and bone turnover markers (BTMs) after discontinuation of bisphosphonates.

METHODS

This observational retrospective study included 264 patients from 14 Spanish rheumatology departments. Postmenopausal women or men with osteoporosis received alendronate or risedronate for ≥ 5 years or zoledronate for ≥ 3 years and had discontinued treatment for ≥ 1 year or ≥ 2 years, respectively. Spinal X-rays were obtained before discontinuation and in suspected clinical vertebral fracture during follow-up. BMD and BTMs were determined before discontinuation and at different time points.

RESULTS

The mean discontinuation time was 2.7 (± 6.7) years. Thirty-two patients (12.3%) had 36 fractures, mainly clinical vertebral fractures. The main risk factor for fracture was a high-risk profile (femoral neck T-score ≤ -2.5 and/or a history of fracture and/or multiple fractures [≥ 5 years]) before discontinuation. At 12 months, 10.41% of patients with high-risk profile experienced a fracture, being 0.8% and 1.08% in moderate- and low-risk patients, respectively. Significant BMD loss at the femoral neck and total hip was detected, with duration of discontinuation being the key factor. PINP was the marker with the greatest changes.

CONCLUSIONS

We identified a profile of patients with osteoporosis who should not discontinue bisphosphonates, owing to the possibility of fractures, especially vertebral, which are already evident the first year after discontinuation.

Factors influencing therapeutic efficacy of denosumab against osteoporosis in systemic lupus erythematosus

OBJECTIVE

Osteoporosis is a common comorbidity in patients with SLE, and bone loss in patients with SLE has a multifactorial aetiology. This study aimed to evaluate the therapeutic efficacy of denosumab in patients with SLE with osteoporosis and to analyse the factors influencing therapeutic efficacy.

METHODS

A total of 166 patients with SLE with osteoporosis who initiated denosumab between January 2016 and December 2023 were included. Changes in the T-score and areal bone mineral density (BMD) at the lumbar spine, total hip and femur neck from denosumab initiation to 12 months were measured. Correlation analysis was performed between the degree of BMD improvement and covariates including SLE-specific factors such as SLE duration, SLE Disease Activity Index 2000 (SLEDAI-2K) score, glucocorticoid dose and hydroxychloroquine use. Multiple linear regression analysis was conducted to identify predictors of the therapeutic efficacy of denosumab.

RESULTS

Denosumab significantly increased BMD and decreased bone turnover markers at 12 months compared with baseline. The degree of BMD improvement revealed a significant negative correlation with SLEDAI-2K score, hydroxychloroquine use, prior osteoporosis treatment and baseline BMD values. In contrast, body mass index and c-telopeptide of collagen type 1 levels were positively correlated with the degree of BMD improvement. Higher baseline BMD values, SLEDAI-2K scores and hydroxychloroquine use were significant predictors of attenuated BMD improvement.

CONCLUSIONS

Our study suggests that denosumab is an effective treatment option for osteoporosis in patients with SLE. The therapeutic efficacy of denosumab can be predicted by baseline BMD values, SLEDAI-2K scores and hydroxychloroquine use.

Association of Delayed Denosumab Dosing with Increased Risk of Fractures: A Population-Based Retrospective Study

BACKGRUOUND

Inhibitory effects of denosumab on bone remodeling are reversible and disappear once treatment is discontinued. Herein, we examined whether and to what extent delayed denosumab administration is also associated with fracture risk using nation-wide data.

METHODS

The study cohort included women aged 45 to 89 years who were started on denosumab for osteoporosis between October 2017 and December 2019 using data from the Korean Health Insurance Review and Assessment service. Participants were stratified according to the time of their subsequent denosumab administration from the last denosumab administration, including those with within 30 days early dosing (ED30), within the planned time of 180-210 days (referent), within 30-90 days of delayed dosing (DD90), within 90-180 days of delayed dosing (DD180), and longer than 181 days of delayed dosing (DD181+). The primary outcome was the incidence of all clinical fractures.

RESULTS

A total of 149,199 participants included and 2,323 all clinical fractures (including 1,223 vertebral fractures) occurred. The incidence of all fractures was significantly higher in the DD90 compared to reference group (hazard ratio [HR], 1.2; 95% confidence interval [CI], 1.1 to 1.4). The risk of all fracture was even higher in the longer delayed DD180 group (HR, 1.9; 95% CI, 1.6 to 2.3) and DD181+ group (HR, 1.8; 95% CI, 1.5 to 2.2). Increased risks of fractures with delayed dosing were consistently observed for vertebral fractures.

CONCLUSION

Delayed denosumab dosing, even by 1 to 3 months, was significantly associated with increased fracture risk. Maintaining the correct dosing schedule should be emphasized when starting denosumab.

Treating osteoporosis in patients with atypical femoral fracture

Patients who have suffered an atypical femoral fracture while on bisphosphonates or denosumab may continue to be at risk for typical osteoporotic fractures. There are no studies to provide guidance on safe treatment for such patients. Instead, using an illustrative case, 5 principles of management are provided that may lead to decreased osteoporotic fracture risk. The first principle is to discontinue the anti-resorptive medications, which may be challenging for the patient on denosumab because of rebound vertebral fractures reported in patients stopping denosumab. The second principle is to maximize non-pharmacologic management to reduce falls and fractures. Home safety, other methods of fall risk reduction, adequate nutrition, and an exercise prescription should help reduce fracture risk. Investigating potential secondary causes of osteoporosis, particularly if the original workup was not comprehensive, is the third principle because treatment of some specific causes may lower fracture risk. Reviewing the medication list is the fourth principle, with the goal of eliminating drugs that may increase fracture risk, and considering thiazides for some patients, which may lower fracture risk. Finally, some patients may benefit from anabolic therapy. One potential (but not FDA-approved) method is to use long-term cyclic teriparatide or abaloparatide on a 3-mo on, 3-mo off schedule. Tailoring the approach to each patient is important, based on the 5 clinical principles, in the absence of evidence-based management recommendations.

Pharmacological Interventions Targeting Pain in Fibrous Dysplasia/McCune-Albright Syndrome

Fibrous dysplasia (FD) is a rare, non-inherited bone disease occurring following a somatic gain-of-function R201 missense mutation of the guanine-nucleotide binding protein alpha subunit stimulating activity polypeptide 1 (GNAS) gene. The spectrum of the disease ranges from a single FD lesion to a combination with extraskeletal features; an amalgamation with café-au-lait skin hyperpigmentation, precocious puberty, and other endocrinopathies defines McCune-Albright Syndrome (MAS). Pain in FD/MAS represents one of the most prominent aspects of the disease and one of the most challenging to treat-an outcome driven by (i) the heterogeneous nature of FD/MAS, (ii) the variable presentation of pain phenotypes (i.e., craniofacial vs. musculoskeletal pain), (iii) a lack of studies probing pain mechanisms, and (iv) a lack of rigorously validated analgesic strategies in FD/MAS. At present, a range of pharmacotherapies are prescribed to patients with FD/MAS to mitigate skeletal disease activity, as well as pain. We analyze evidence guiding the current use of bisphosphonates, denosumab, and other therapies in FD/MAS, and also discuss the potential underlying pharmacological mechanisms by which pain relief may be achieved. Furthermore, we highlight the range of presentation of pain in individual cases of FD/MAS to further describe the difficulties associated with employing effective pain treatment in FD/MAS. Potential next steps toward identifying and validating effective pain treatments in FD/MAS are discussed, such as employing randomized control trials and probing new pain pathways in this rare bone disease.

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.

Atypical Ulnar Fracture in an Older Woman with Osteoporosis with a Five-Year History of Denosumab Treatment: A Case Report

Atypical ulnar fracture (AUF) is a rare condition that may occur in patients treated with bisphosphonates. We describe the clinical course of a patient who had an AUF during treatment with denosumab. An 86-year-old woman treated with denosumab for 5 years experienced a complete transverse fracture of the proximal left ulna after falling from a standing height. Intraoperative photographs showed cortical thickening around the fracture site. Therefore, we diagnosed the patient with AUF and performed internal fixation with a locking plate. However, a re-fracture occurred 2.5 months after surgery, which was treated with locking plate replacement with a longer one with a bone graft. One year after the second surgery, the fracture healed. To our knowledge, this is the second case report of an AUF occurring during denosumab treatment. Our case highlights the importance of careful follow-up of patients receiving not only bisphosphonate, but also denosumab.

Levels of Evidence: Level V (Therapeutic)

Analysis of the subsequent treatment of osteoporosis by transitioning from bisphosphonates to denosumab, using quantitative computed tomography: A prospective cohort study

Purpose

Denosumab reduces bone resorption and improves bone mineral density (BMD). Studies have analyzed subsequent treatment transitioning from bisphosphonates to denosumab based on dual-energy X-ray absorptiometry scanning (DXA). Quantitative computed tomography (QCT) can help assess cortical and trabecular bones separately in three dimensions without the interference of the surrounding osteophytes. In the present study, we analyzed the subsequent treatment transition from bisphosphonates to denosumab using QCT.

Methods

Thirty-two patients with postmenopausal osteoporosis to be treated with denosumab were recruited. The patients were divided into two groups (15 prior bisphosphonate and 17 naïve) based on their previous treatment. BMD of the lumbar spine and hip were evaluated by DXA and QCT at baseline and 12 months following denosumab treatment.

Results

The percentage change in volumetric BMD assessed by QCT at 12 months significantly improved in the naïve group compared with that in the prior bisphosphonate group. The region-specific assessment of femur at 12 months revealed that denosumab treatment was effective in both cortical and trabecular bones except the trabecular region of the prior bisphosphonate group.

Conclusion

Our study suggests that although denosumab treatment was useful in both treatment groups, BMD increase was significantly higher in the naïve group than in the prior-bisphosphonate group. Interestingly, in the prior-bisphosphonate group, denosumab treatment was more effective in the cortical region than the trabecular region. Our study offers insights into the subsequent treatment and permits greater confidence when switching to denosumab from bisphosphonates.

•

We analyzed the treatment transition from bisphosphonates to denosumab using QCT.

•

Percentage change in volumetric BMD at 12 months significantly improved in the naïve group.

•

Denosumab treatment was more effective on the cortical region than the trabecular region.

•

Our study offers insights into the subsequent treatment when switching to denosumab.

On the pharmacological evaluation of bisphosphonates in humans

One of the key parameters for a successful treatment with any drug is the use of an optimal dose regimen. Bisphosphonates (BPs) have been in clinical use for over five decades and during this period clinical pharmacokinetic (PK) and pharmacodynamic (PD) evaluations have been instrumental for the identification of optimal dose regimens in patients. Ideal clinical PK and PD studies help drug developers explain variability in responses and enable the identification of a dose regimen with an optimal effect. PK and PD studies of the unique and rather complex pharmacological properties of BPs also help determine to a significant extent ideal dosing for these drugs. Clinical PK and PD evaluations of BPs preferably use study designs and assays that enable the assessment of both short- (days) and long-term (years) presence and effect of these drugs in patients. BPs are mainly used for metabolic bone diseases because they inhibit osteoclast-mediated bone resorption and the best way to quantify their effects in humans is therefore by measuring biochemical markers of bone resorption in serum and urine. In these very same samples BP concentrations can also be measured. Short-term serum and urine data after both intravenous (IV) and oral administration enable the assessment of oral bioavailability as well as the amount of BP delivered to the skeleton. Longer-term data provide information on the anti-resorptive effect as well as the elimination of the BP from the skeleton. Using PK-PD models to mathematically link the anti-resorptive action of the BPs to the amount of BP at the skeleton provides a mechanism-based explanation of the pattern of bone resorption during treatment. These models have been used successfully during the clinical development of BPs. Newer versions of such models, which include systems pharmacology and disease progression models, are more comprehensive and include additional PD parameters such as BMD and fracture risk. Clinical PK and PD studies of BPs have been useful for the identification of optimal dose regimens for metabolic bone diseases. These analyses will also continue to be important for newer research directions, such as BP use in the delivery of other drugs to the bone to better treat bone metastases and bone infections, as well as the potential benefit of BPs at non-skeletal targets for the prevention and treatments of soft tissue cancers, various fibroses, and other cardiovascular and neurodegenerative diseases, and reduction in mortality and extension of lifespan.

Clinical evidence of the effect of bisphosphonates on pregnancy and the infant

Bisphosphonates (BPs) are potent inhibitors of osteoclast mediated bone resorption. These drugs are widely used in the management of osteoporosis and other diseases, characterized by high bone turnover. The effect of BPs on gestation and lactation, when they are used as therapeutic agents in premenopausal women, is yet unknown. We conducted a detailed literature review and identified the cases of BPs use in young women, as well as, the effects of this therapy on the gestation and the embryo. The published data, regarding the use of BPs in premenopausal women and their effects on the pregnancy outcome, are limited. However, we could identify the outcomes of 40 pregnant women, who had received BPs prior to or during pregnancy, that have been documented in the literature. All women had valid indications to receive BPs for serious bone metabolism conditions. We could not identify any prospective trials, which focus on pregnancy outcomes following after the in-utero exposure to BPs. In total, no serious adverse effects were reported. Problems related to the offspring, such as hypocalcemia and a tendency for low body weight (LBW), were self-resolving. In addition, no serious adverse outcomes were reported for women having completed pregnancy. Nevertheless, follow-up was limited for both outcomes suggesting the necessity of national and international registries.

Pharmacology of bisphosphonates

The biological effects of the bisphosphonates (BPs) as inhibitors of calcification and bone resorption were first described in the late 1960s. In the 50 years that have elapsed since then, the BPs have become the leading drugs for the treatment of skeletal disorders characterized by increased bone resorption, including Paget's disease of bone, bone metastases, multiple myeloma, osteoporosis and several childhood inherited disorders. The discovery and development of the BPs as a major class of drugs for the treatment of bone diseases is a paradigm for the successful journey from "bench to bedside and back again". Several of the leading BPs achieved "blockbuster" status as branded drugs. However, these BPs have now come to the end of their patent life, making them highly affordable. The opportunity for new clinical applications for BPs also exists in other areas of medicine such as ageing, cardiovascular disease and radiation protection. Their use as inexpensive generic medicines is therefore likely to continue for many years to come. Fifty years of research into the pharmacology of bisphosphonates have led to a fairly good understanding about how these drugs work and how they can be used safely in patients with metabolic bone diseases. However, while we seemingly know much about these drugs, a number of key aspects related to BP distribution and action remain incompletely understood. This review summarizes the existing knowledge of the (pre)clinical and translational pharmacology of BPs, and highlights areas in which understanding is lacking.

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Risks and Benefits of Bisphosphonate Therapies

Bisphosphonates are the mainstay of osteoporosis treatment but also play a fundamental role in treating other bone diseases such as Osteogenesis Imperfecta, Pagets' disease, and in the prevention of adverse skeletal effects in certain cancers such as prostate cancer or multiple myeloma. In the last decades, the refinement of bisphosphonates and an increase in the number of new bisphosphonates commercialized has altered the clinical management of these diseases. Despite differences between randomized controlled trials and observational studies, overall all bisphosphonates licensed have proven to reduce the risk of fracture through the inhibition of bone resorption. Other beneficial effects include pain reduction in bone metastasis and potentially a decrease in mortality. However, the chronic nature of most of these disorders implies long-term treatments, which can be associated with long-term adverse effects. Some of the adverse effects identified include an increased risk of atypical femur fractures, osteonecrosis of the jaw, gastrointestinal side effects, or atrial fibrillation. The harm/benefit thinking and the constant update regarding these medications are vital in the day-to-day decision-making in clinical practices. The aims of this review are to compile the basic characteristics of these drugs and outline the most important benefits and side effects and provide a clinical context as well as a research agenda to fill the gaps in our knowledge.

Neonatal transient hypophosphatemic hypercalciuric rickets in dizygous twins: A role for maternal alendronate therapy before pregnancy or antireflux medications?

BACKGROUND

Bisphosphonates (BP) are sometimes used in children and young women, but their use requires expertise and caution due to the relative lack of long-term efficacy and safety data.

CLINICAL CASES

We report on two dizygotic male twins with a past of mild prematurity who presented at the age of 2 months with moderate clinical craniotabes, hypophosphatemia, normal circulating calcium, severe hypercalciuria, and low parathyroid hormone levels. Following supplementation with oral phosphorus and native vitamin D, the clinical and biological abnormalities disappeared within 2 months. Since the twins were dizygotic and were identical in terms of clinical presentation and progression, the only likely explanation for these transient mineral abnormalities was prenatal or neonatal exposure to a toxic agent. Taking into account their medical past, two drugs were possibly involved: either oral alendronate that their mother had received before pregnancy for misdiagnosed osteoporosis or antireflux medications, or both.

DISCUSSION

We believe that these two cases could correspond to the first description of a potential mother-to-fetus transmission of alendronate, inducing early and transient hypophosphatemic rickets, the clinical picture being worsened by the antireflux drugs impairing intestinal phosphate absorption. For pediatric rheumatologists, this raises the question of more clearly defining the indications for BP in female children and teenagers; for rheumatologists, this also demonstrates the importance of correctly diagnosing osteoporosis and not using BP off-label, especially in women of child-bearing age.

Managing Osteoporosis in Patients on Long-Term Bisphosphonate Treatment: Report of a Task Force of the American Society for Bone and Mineral Research

Bisphosphonates (BPs) are the most commonly used medications for osteoporosis. This ASBMR report provides guidance on BP therapy duration with a risk-benefit perspective. Two trials provided evidence for long-term BP use. In the Fracture Intervention Trial Long-term Extension (FLEX), postmenopausal women receiving alendronate for 10 years had fewer clinical vertebral fractures than those switched to placebo after 5 years. In the HORIZON extension, women who received 6 annual infusions of zoledronic acid had fewer morphometric vertebral fractures compared with those switched to placebo after 3 years. Low hip T-score, between -2 and -2.5 in FLEX and below -2.5 in HORIZON extension, predicted a beneficial response to continued therapy. Hence, the Task Force suggests that after 5 years of oral BP or 3 years of intravenous BP, reassessment of risk should be considered. In women at high risk, for example, older women, those with a low hip T-score or high fracture risk score, those with previous major osteoporotic fracture, or who fracture on therapy, continuation of treatment for up to 10 years (oral) or 6 years (intravenous), with periodic evaluation, should be considered. The risk of atypical femoral fracture, but not osteonecrosis of the jaw, clearly increases with BP therapy duration, but such rare events are outweighed by vertebral fracture risk reduction in high-risk patients. For women not at high fracture risk after 3 to 5 years of BP treatment, a drug holiday of 2 to 3 years can be considered. The suggested approach for long-term BP use is based on limited evidence, only for vertebral fracture reduction, in mostly white postmenopausal women, and does not replace the need for clinical judgment. It may be applicable to men and patients with glucocorticoid-induced osteoporosis, with some adaptations. It is unlikely that future trials will provide data for formulating definitive recommendations. © 2015 American Society for Bone and Mineral Research.

Comparing clinical and economic outcomes of biologic and conventional medications in postmenopausal women with osteoporosis

RATIONALE, AIMS AND OBJECTIVES

Biologics are substantially more expensive than their conventional counterparts but it is unclear whether extra costs deliver better health outcomes. We compare clinical and economic outcomes between teriparatide (monthly costs $1120) and bisphosphonates (monthly costs $14) among postmenopausal women with osteoporosis.

METHODS

From a 5% random sample of Medicare beneficiaries, we selected women newly diagnosed with osteoporosis between 1 January 2007 and 31 December 2011 and who initiated teriparatide or bisphosphonates after the diagnosis. We followed them up until one of these events: switching osteoporosis treatment, death, or the end of study period - 31 December 2011. Clinical outcomes included hip fracture, vertebral fracture, fracture of radius, ulna or carpal bones, other upper limb fractures, other lower limb fractures and any fracture. Economic outcomes included medical costs, pharmacy costs, and total costs associated with osteoporosis. Using conventional propensity score, high-dimensional propensity score and instrumental variable analysis, we constructed Cox proportional hazards models to evaluate the risk of fracture and two-part models to compare costs.

RESULTS

Teriparatide users had higher risk of fracture and higher costs, compared with similar bisphosphonates users. The hazard ratios of fracture for teriparatide relative to bisphosphonates ranged from 1.37 to 2.12, depending on methods. There was no difference in the risk of hip fracture between treatment groups. Total annual costs related to osteoporosis were between $2733 and $3352 higher for teriparatide users.

CONCLUSIONS

The biological agent, teriparatide, is more expensive yet less effective than conventional treatment, bisphosphonates.

Osteoporotic vertebral fractures during pregnancy: be aware of a potential underlying genetic cause

CONTEXT

Although the baby growing in its mother's womb needs calcium for skeletal development, osteoporosis and fractures very rarely occur during pregnancy.

CASE PRESENTATION

A 27-year-old woman in the seventh month of her first pregnancy contracted midthoracic back pain after lifting an object. The pain was attributed to her pregnancy, but it remained postpartum. Her past medical history was uneventful, except for severely reduced vision of her left eye since birth. Family history revealed that her maternal grandmother had postmenopausal osteoporosis and her half-brother had three fractures during childhood after minor trauma. Her height was 1.58 m; she had no blue sclerae or joint hyperlaxity. Laboratory examination including serum calcium, phosphate, alkaline phosphatase, creatinine, β-carboxyterminal cross-linking telopeptide of type I collagen, 25-hydroxyvitamin D, and TSH was normal. Multiple thoracic vertebral fractures were diagnosed on x-ray examination, and dual-energy x-ray absorptiometry scanning showed severe osteoporosis (Z-scores: L2-L4, -5.6 SD; femur neck, -3.9 SD). DNA analyses revealed two compound heterozygous missense mutations in LRP5. The patient's mother carried one of the LRP5 mutations and was diagnosed with osteoporosis. Her half-brother, treated with cabergoline for a microprolactinoma, also had osteoporosis of the lumbar spine on dual-energy x-ray absorptiometry and carried the same LRP5 mutation. The patient was treated with risedronate for 2.5 years. Bone mineral density and back pain improved. She stopped bisphosphonate use 6 months before planning a second pregnancy.

CONCLUSION

Our patient was diagnosed with osteoporosis pseudoglioma syndrome/familial exudative vitreoretinopathy. Potential underlying genetic causes should be considered in pregnancy-associated osteoporosis with implications for patients and relatives. More studies regarding osteoporosis treatment preceding conception are desirable.

Safety issues with bisphosphonate therapy for osteoporosis

Randomized controlled trials have demonstrated the efficacy of bisphosphonates (BP) in improving BMD and reducing fracture risk. Various safety issues that were not noted in clinical trials have, however, now emerged with post-marketing surveillance and increasing clinical experience. The risk of atypical femoral fracture could increase with long-term use of BP, although absolute risk is very small, particularly when balanced against benefits. A drug holiday should be considered after 5 years of treatment for patients at low risk of fracture, although there is no official recommendation regarding this to guide clinicians. Osteonecrosis of the jaw from low-dose BP used for osteoporosis is very rare, and mainly a complication with high-dose i.v. BP used in oncology. The risk of atrial fibrillation too is negligible, and a definite link cannot be established between BP and oesophageal cancer. BP should be avoided in patients with severe renal impairment and during pregnancy and lactation because of limited safety data. Further epidemiological and clinical data are required to establish safety of BP in long-term users (>5 years) and provide evidence-based management.

Distribution of serum βCTX in a population-based study of postmenopausal women taking into account different anti-osteoporotic therapies (the FRODOS Cohort)

This cross-sectional study evaluated the distribution of serum cross-linked C-telopeptides of collagen type I (βCTXs) in postmenopausal women, the characteristics of bone remodeling, and the factors influencing this bone marker, especially the use of anti-osteoporotic drugs. Women (n = 4,175) aged 59-70 years randomly selected from the community were invited to participate, measuring βCTXs and lumbar and femoral bone mineral density at recruitment. Risk factors for osteoporosis and the use of anti-osteoporotic treatment were collected with a structured questionnaire. We evaluated the percentage of women with increased (βCTXs >0.620 ng/mL) and decreased bone turnover (βCTXs <0.100 ng/mL) and those reaching the so-called treatment target (values of βCTXs within the lower half of the reference range for healthy young premenopausal women). Two thousand nine hundred sixty-eight women (70 %) participated (2,405 non-treated and 563 treated). Increased and decreased bone turnover was observed in 16.4 and 1.8 %, respectively, of non-treated women with significant differences compared with treated women (9.7 and 14.2 %, respectively, p < 0.001); 28 % of non-treated osteoporotic individuals had increased bone turnover versus 14 % of osteopenic participants and 8.8 % of women with normal bone density (p < 0.001). Women receiving bisphosphonates presented the highest percentages of decreased bone turnover (27 %) and βCTXs (43 %) within the treatment target. Increased bone turnover is observed in 16.4 % of non-treated postmenopausal women and is more frequent in individuals with osteoporosis, whereas decreased bone turnover is unusual. Most participants taking bisphosphonates had values within the treatment target, but nearly one quarter had decreased bone turnover.

Equilibrium-dependent bisphosphonate interaction with crystalline bone mineral explains anti-resorptive pharmacokinetics and prevalence of osteonecrosis of the jaw in rats

Bisphosphonates (BPs) are chemically stable analogs of pyrophosphate exhibiting strong affinity to bone and have been used for the treatment of diseases characterized by excessive bone resorption. Contrary to the widely accepted BP accumulation model in bone after repeated applications, we report here that an equilibrium-dependent BP-crystalline bone mineral interaction may better explain BP bio-distribution and anti-catabolic bone remodeling and may be relevant to the appearance of osteonecrosis of the jaw (ONJ) in rats. Fluorescent-labeled BP analogs were synthesized and used to evaluate the mode of bone adsorption. After fluorescent-labeled BP adsorbed on crystalline calcium phosphates in vitro, subsequent BP application replaced the previously absorbed BP depending on the dose and the relative binding affinity to hydroxyapatite. The in vivo intravenous zoledronate (ZOL) injection of repeated fractional doses resulted in lower serum CTX and TRAP5b measurements than a single bolus injection in spite of the equivalent cumulative dose. Repeated injections resulted in the distribution of fluorescent-labeled BP on the large area of bone surfaces; whereas the single bolus injection gave rise to the intense BP bio-distribution at selected bone sites such as the alveolar process of jawbones. Necrotic maxillary alveolar bone was predominantly observed in vitamin D deficiency rats treated with bolus ZOL injection. The palatal necrotic bone was characteristically sequestrated by the fistulation of hyperplastic oral epithelium, suggesting the initial development of ONJ-like lesions in rats. Our results suggest that equilibrium-dependent BP-bone interaction may, in part, determine the effectiveness and influence side effects of long-term and repeated applications of BPs.