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

Improvement of osteoblast adhesion, viability, and mineralization by restoring the cell cytoskeleton after bisphosphonate discontinuation in vitro

OBJECTIVE

Bisphosphonates are prescribed to treat excessive bone resorption in patients with osteoporosis. However, its use is associated with potential adverse effects such as medication-related osteonecrosis of the jaw, prompting the introduction of the drug holiday concept in patients prior to dentoalveolar surgery. Furthermore, bisphosphonate discontinuation has been studied in vivo, in humans, and in animal models. However, it is not known whether this approach could affect bone cells in vitro. Therefore, the objective of this study was to investigate the potential effects of bisphosphonate discontinuation on pre-osteoblast and osteoblast activities in vitro.

METHODOLOGY

Pre-osteoblasts (MC3T3) and osteoblasts were treated with bisphosphonate (alendronate) at concentrations of 1, 5, and 10 µM. Alendronate was then withdrawn at different time points. The negative control consisted of untreated cells (0 µM), while the positive control consisted of cells incubated with alendronate throughout the experiment. Cell viability, cell adhesion, cell cytoskeleton, mineralization, and gene expressions were investigated.

RESULTS

Pre-osteoblasts and osteoblasts showed a decrease in cell viability after treatment with 5-10 μM alendronate for 4 days or longer. Two days of alendronate discontinuation significantly increased cell viability compared with the positive control. However, these levels did not reach those of the negative control. Bone nodule formation was reduced by alendronate. Discontinuation of alendronate regained bone nodule formation. Longer periods of discontinuation were more effective in restoring nodule formation than shorter periods. Addition of alendronate resulted in an increase in the percentage of dead cells, which, in turn, decreased when alendronate was discontinued. Alendronate affected the cell cytoskeleton by disassembling actin stress fibers. Cell adhesion and cell morphological parameters were also affected by alendronate. Discontinuation of alendronate restored cell adhesion and these parameters. Overall, the highest improvement after alendronate discontinuation was seen at 10 µM. However, alendronate treatment and discontinuation did not affect osteoblast gene expression.

CONCLUSION

Discontinuation of alendronate helps to reverse the negative effects of the drug on cell viability, cell adhesion, and mineralization by restoring the cell cytoskeleton. Our data suggest the benefits of drug holiday and/or intermittent strategies for alendronate administration at the cellular level.

Comparison of bone mineral density of osteoporotic and osteopenia menopausal women treated with oral bisphosphonates before stopping the treatment and 1 year after drug holiday period

BACKGROUND

Osteoporosis is a skeletal and bone disorder characterized by bone fractures and decreased bone mineral density (BMD). Bisphosphonates have a great tendency to bind to minerals, and their long-term use can increase the risk of bone fragility in patients. Stopping bisphosphonates after a period of time is called a drug holiday (DH). Recent evidence has shown that patients' BMD may decrease again during DH. However, few studies have been done in this regard. In the present study, we compared the BMD of postmenopausal women during bisphosphonates treatment and 1 year after DH.

MATERIAL AND METHODS

A total of 202 patients were selected with osteopenia (n = 95) and osteoporosis (n = 107); they had been treated with alendronate for 5 years (a rheumatologist confirmed the diagnosis of osteopenia and osteoporosis) and had undergone DH for 1 year. At the arrival of all patients, BMD was checked with the DXA (dual-energy X-ray absorptiometry) method using the 2007 American Explorer model Hologic device based on the Caucasian race. One year later, patients were reassessed for BMD by the same device.

RESULT

The analysis of femoral neck (FN) and lumbar spine (LS) T-score indices in the osteopenia and the osteoporosis groups showed reduction after DH, and the difference was statistically significant in both groups (p = 0.001). After 1 year of stopping bisphosphonate treatment, the average of FN and LS BMD decreased in both groups (p = 0.001).

CONCLUSION

In general, it can be said that DH can reduce FN and LS T-scores. The results indicated a significant reduction in BMD after the DH period for both the osteoporosis and osteopenia groups in the early months. Also, the effect of DH in osteoporosis patients was more compared to the osteopenia individuals, which could have implications for their treatment approach, and also its effect on bone health. Key Points • The DH can reduce FN and LS T-scores • The BMD reduced after the DH period for both the osteoporosis and osteopenia groups • After 1 year of stopping bisphosphonate treatment, the average of FN and LS BMD decreased in both groups.

Prolonged bone health benefits for breast cancer patients following adjuvant bisphosphonate therapy: the BoHFAB study

Adjuvant bisphosphonates are often recommended in postmenopausal women with early breast cancer at intermediate-to-high risk of disease recurrence, but the magnitude and duration of their effects on bone mineral density (BMD) and bone turnover markers (BTMs) are not well described. We evaluated the impact of adjuvant zoledronate on areal BMD and BTMs in a sub-group of patients who had completed the large 5-yr randomized Adjuvant Zoledronic Acid to Reduce Recurrence (AZURE) trial. About 224 women (recurrence free) who had completed the AZURE trial within the previous 3 mo were recruited from 20 UK AZURE trial sites. One hundred twenty had previously been randomized to zoledronate (19 doses of 4 mg over 5 yr) and 104 to the control arm. BMD and BTMs were assessed at sub-study entry, 6 (BTMs only), 12, 24, and 60 mo following the completion of AZURE. As expected, mean BMD, T-scores, and Z-scores at sub-study entry were higher in the zoledronate vs the control arm. At the lumbar spine, the mean (SD) standardized BMD (sBMD) was 1123 (201) and 985 (182) mg/cm2 in the zoledronate and control arms, respectively (P < .0001). The baseline differences in sBMD persisted at all assessed skeletal sites and throughout the 5-yr follow-up period. In patients completing zoledronate treatment, BTMs were significantly lower than those in the control arm (α- and β-urinary C-telopeptide of type-I collagen, both P < .00001; serum intact pro-collagen I N-propeptide, P < .00001 and serum tartrate-resistant acid phosphatase 5b, P = .0001). Some offset of bone turnover inhibition occurred in the 12 mo following the completion of zoledronate treatment. Thereafter, during the 60 mo of follow-up, all BTMs remained suppressed in the zoledronate arm relative to the control arm. In conclusion, in addition to the known anti-cancer benefits of adjuvant zoledronate, there are likely to be positive, lasting benefits in BMD and bone turnover.

Combined chemotherapy of zoledronic acid and pamidronate in the treatment of bone metastases from nonsmall cell lung cancer and the effects on pain stress and bone metabolic indices

OBJECTIVE

We conducted this paper to decipher the efficacy of the combined chemotherapy of zoledronic acid and pamidronate in treating bone metastases from nonsmall cell lung cancer (NSCLC) and the effects on pain stress and bone metabolic indices.

METHODS

Patients with bone metastases from NSCLC were allocated into Group A and Group B. Patients in the Group A were administrated with pamidronate combined chemotherapy and patients in the Group B were administrated with zoledronic acid combined chemotherapy. The efficacy, pain symptom scores, quality of life scores, serum inflammatory factor, serum bone metabolic indices, serum pain stress indicators, and the occurrence of adverse effects were compared in patients of the two groups.

RESULTS

The total effective rate of treatment was higher in the Group B than in the Group A. After treatment, reduced Numerical Rating Scale scores and elevated Karnofsky Performance Score score, reduced serum levels of N-terminal mid-fragment of osteocalcin, N-terminal propeptide of type I procollagen, bone-specific alkaline phosphatase, and type I collagen hydroxyl terminal peptide β special sequence, reduced serum levels of C-reactive protein, procalcitonin, tumor necrosis factor-α, and interleukin-6, as well as decreased levels of bradykinin, substance P, neuropeptide Y, and β-endorphin were found in the Group B versus the Group A. No notable difference was witnessed in the rate of adverse reactions between the Group A and the Group B.

CONCLUSION

Zoledronic acid combined with chemotherapy can effectively treat bone metastases of NSCLC and improve pain stress and bone metabolic status, which has value that can be promoted and applied in clinical treatment.

The Sequential Therapy in Osteoporosis

Background

Osteoporosis management often involves a sequential treatment approach to optimize patient outcomes and minimize fracture risks. This strategy is tailored to individual patient characteristics, treatment responses, and fracture risk profiles.

Methods

A thorough literature review was systematically executed using prominent databases, including PubMed and EMBASE. The primary aim was to identify original articles and clinical trials evaluating the effectiveness of sequential therapy with anti-osteoporosis drugs, focusing on the period from 1995 to 2023. The analysis encompassed an in-depth examination of osteoporosis drugs, delineating their mechanisms of action, side effects, and current trends as elucidated in the literature.

Results and Discussion

Our study yielded noteworthy insights into the optimal sequencing of pharmacologic agents for the long-term treatment of patients necessitating multiple drugs. Notably, the achievement of optimal improvements in bone mass is observed when commencing treatment with an anabolic medication, followed by the subsequent utilization of an antiresorptive drug. This stands in contrast to initiating therapy with a bisphosphonate, which may potentially diminish outcomes in the post-anabolic intervention period. Furthermore, it has been discerned that caution should be exercised against transitioning from denosumab to PTH homologs due to the adverse effects of heightened bone turnover and sustained weakening of bone structure. Despite the absence of fracture data substantiating the implementation of integrated anabolic/antiresorptive pharmacotherapy, the incorporation of denosumab and teriparatide presents a potential avenue worthy of consideration for individuals at a heightened vulnerability to fragility fractures.

Conclusions

A judiciously implemented sequential treatment strategy in osteoporosis offers a flexible and tailored approach to address diverse clinical scenarios, optimizing fracture prevention and patient outcomes.

Bone loss after denosumab discontinuation is prevented by alendronate and zoledronic acid but not risedronate: a retrospective study

A retrospective study of 121 patients who stopped denosumab (Dmab) then received no treatment (NT), risedronate (RIS), alendronate (ALN), or zoledronic acid (ZOL). Bone density (spine and hip) during and after Dmab discontinuation was measured. Treatment with ALN or ZOL, not NT and RIS, mitigated BMD loss after Dmab discontinuation.

INTRODUCTION

Denosumab (Dmab) discontinuation is associated with bone loss and multiple vertebral fractures. The purpose was to compare bone mineral density (BMD) change in patients following Dmab discontinuation with no subsequent treatment (NT) and three bisphosphonate (BP) treatments: risedronate (RIS), alendronate (ALN), and zoledronic acid (ZOL).

METHODS

In a review of 121 patients aged 71.2 ± 8.1 years, discontinuing Dmab (mean 5.4 doses), 33 received NT and 88 received BP (22 RIS; 34 ALN; 32 ZOL). BMD change after 1 year was compared between groups at the lumbar spine (LS), femoral neck (FN), and total hip (TH). Risk factors for bone loss after Dmab discontinuation were compared between groups and incidence of vertebral fractures was determined.

RESULTS

Following Dmab discontinuation, LS mean change (g/cm2; 95% CI) was for NT: - 0.041 (- 0.062 to - 0.021); RIS: - 0.035 (- 0.052 to - 0.017); ALN: - 0.005 (- 0.020 to 0.009); and ZOL: - 0.009 (- 0.025 to 0.008). Differences in LS were found between NT and ALN (p =  0.015), and NT and ZOL (p=0.037), but not between NT and RIS. The only significant difference in TH was found between NT and ZOL (p 0.034) with no group differences in FN. BMD gains during Dmab treatment were associated with BMD loss after Dmab discontinuation. In a subset, discontinuation after Dmab treatment (> 5 doses) followed by ALN (n = 22) and ZOL (n = 11) showed no difference in BMD. Five of 7 vertebral fractures occurred after Dmab discontinuation in NT.

CONCLUSION

Subsequent treatment with ALN or ZOL but not NT and RIS mitigates BMD loss after Dmab discontinuation.

A Vitronectin-Derived Peptide Restores Ovariectomy-Induced Bone Loss by Dual Regulation of Bone Remodeling

BACKGROUND

Bone remodeling is tightly regulated through bone resorption and bone formation; imbalances in bone remodeling can cause various pathological conditions such as osteoporosis. Antiresorptive agents commonly used for treating osteoporosis do not substantially reverse osteoporotic bone loss.

METHODS

We evaluated the effects of the RVYFFKGKQYWE motif (residues 270-281; VnP-16) of human vitronectin on the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and osteoclastogenesis of bone marrow-derived macrophages. The effects of VnP-16 were also assessed in a mouse model of estrogen deficiency-induced osteoporosis (ovariectomized female C57BL/6 mice). To assay whether VnP-16 can reverse ovariectomy-induced bone loss, synthetic peptides or vehicle were subcutaneously injected into ovariectomized mice once a week for 4 weeks (n = 10/group). To evaluate the bone restorative effects of VnP-16, in-vivo micro-computed tomography analysis and histological staining were performed.

RESULTS

VnP-16 induced osteogenic differentiation of hMSCs and inhibited the RANKL-RANK-TRAF6 axis in the osteoclastogenesis signaling pathway. Furthermore, systemic administration of VnP-16 reversed ovariectomy-induced bone loss in the femoral neck, distal femur and lumbar spine by increasing osteoblast differentiation and promoting bone formation, and concomitantly decreasing osteoclastogenesis and inhibiting bone resorption. The bone restorative effect of VnP-16 was observed one week after subcutaneous administration, and although the timing of the effect differed according to bone location, it persisted for at least 3 weeks.

CONCLUSION

Our findings suggest that VnP-16 is a potential therapeutic agent for treating osteoporosis that mediates its effects through dual regulation of bone remodeling.

The why and how of sequential and combination therapy in osteoporosis. A review of the current evidence

It is now well recognized that over the lifetime of a patient with osteoporosis, more than one medication will be needed to treat the disease and to decrease fracture risk. Though current gaps in osteoporosis therapy can be potentially mitigated with sequential and combination regimens, how to move seamlessly amongst the multiple treatments currently available for osteoporosis for sustained efficacy is still unclear. Data from recent studies show that an anabolic agent such as teriparatide or romosozumab followed by an antiresorptive affords maximal gain in BMD and possibly better and earlier fracture risk reduction compared to a regimen which follows the opposite sequence. Sequentially moving to a bisphosphonate such as alendronate from an anabolic agent such as abaloparatide has also been shown to preserve the fracture reduction benefits seen with the latter. This sequence of an anabolic agent followed by an antiresorptive should especially be considered in the high-risk patient with imminent fracture risk to rapidly reduce the risk of subsequent fractures. The data surrounding optimum timing of initiation of bisphosphonate therapy following denosumab discontinuation is still unclear. Though data suggests that combining a bisphosphonate with teriparatide does not provide substantial BMD gains compared to monotherapy, the concomitant administration of denosumab with teriparatide has been shown to significantly increase areal BMD as well as to increase volumetric BMD and estimated bone strength. This narrative review explores the available evidence regarding the various sequential and combination therapy approaches and the potential role they could play in better managing osteoporosis.

EXTENSIVE EXPERTISE IN ENDOCRINOLOGY: Osteoporosis management

Fractures occur in about half of older White women, and almost a third of older White men. However, 80% of the older individuals who have fractures do not meet the bone density definition of osteoporosis, suggesting that this definition is not an appropriate threshold for offering treatment. Fracture risk can be estimated based on clinical risk factors with or without bone density. A combination of calculated risk, fracture history, and bone density is used in treatment decisions. Medications available for reducing fracture risk act either to inhibit bone resorption or to promote bone formation. Romosozumab is unique in that it has both activities. Bisphosphonates are the most widely used interventions because of their efficacy, safety, and low cost. Continuous use of oral bisphosphonates for >5 years increases the risk of atypical femoral fractures, so is usually punctuated with drug holidays of 6-24 months. Denosumab is a further potent anti-resorptive agent given as 6-monthly s.c. injections. It is comparable to the bisphosphonates in efficacy and safety but has a rapid offset of effect after discontinuation so must be followed by an alternative drug, usually a bisphosphonate. Teriparatide stimulates both bone formation and resorption, substantially increases spine density, and reduces vertebral and non-vertebral fracture rates, though data for hip fractures are scant. Treatment is usually limited to 18-24 months, followed by the transition to an anti-resorptive. Romosozumab is given as monthly s.c. injections for 1 year, followed by an anti-resorptive. This sequence prevents more fractures than anti-resorptive therapy alone. Because of cost, anabolic drugs are usually reserved for those at very high fracture risk. 25-hydroxyvitamin D levels should be maintained above 30 nmol/L, using supplements if sunlight exposure is limited. Calcium intake has little effect on bone density and fracture risk but should be maintained above 500 mg/day using dietary sources.

Value of Biochemical Indexes of Bone Metabolism in Predicting Osteoporotic Lumbar Fractures

Objective

To investigate the value of bone metabolism indexes such as type I procollagen N-terminal propeptide (P1NP), 25-hydroxyvitamin D (25(OH)D), osteocalcin (OSTEOC), and parathyroid hormone (PTH) in predicting osteoporotic lumbar fractures.

Methods

120 female patients with osteoporosis treated in our hospital were selected as research objects. There were 76 cases in the fracture group and 44 cases in the nonfracture group. The relationship between the levels of P1NP, 25(OH)D, OSTEOC, and PTH and the incidence of osteoporotic lumbar fractures were detected and compared between the two groups. The predictive value of biochemical indexes of bone metabolism in patients with osteoporosis was analyzed by ROC curve.

Results

The levels of P1NP and PTH in the fracture group were significantly higher than those in the nonfracture group, while 25(OH)D and OSTEOC levels were lower than those in the nonfracture group. Moreover, the levels of P1NP, 25(OH)D, OSTEOC, and PTH are important factors affecting the pathogenesis of osteoporosis. The area under the curve (AUC) of fracture in patients with osteoporosis predicted by the combination of P1NP, 25(OH)D, OSTEOC, and PTH levels was 0.886, which was greater than the AUC predicted by each index (0.796, 0.753, 0.670, and 0.824). The best sensitivity and specificity of comprehensive prediction of each index were 78.95% and 79.10%, respectively.

Conclusion

The abnormal changes of P1NP, 25(OH)D, OSTEOC, and PTH in female patients with osteoporotic lumbar fracture are closely related to the occurrence of the disease. The combination of these indicators has relatively significant application value in predicting the occurrence of fracture, which is helpful to formulate and guide relevant preventive measures for female patients with osteoporotic lumbar fracture and improve the prognosis.

"Pregnancy and Lactation Associated Osteoporosis"

Pregnancy-associated osteoporosis (PAO) is a rare condition of skeletal fragility affecting women in pregnancy or the postpartum period. During normal pregnancy and lactation, substantial changes in calcium metabolism and skeletal physiology occur in order to meet the demands of the developing foetus. Whilst these adaptations are reversible and generally of no clinical consequence for the mother, a small number of women will develop osteoporosis and suffer fragility fractures. Vertebral fractures occur most commonly in PAO and are often multiple. Due to the rarity of PAO, systematic study to date has been limited. Aetiology is poorly understood, but traditional osteoporosis risk factors and genetic factors are likely to play a role. A small number of cases may be due to an underlying metabolic bone disorder or monogenic condition. Management of PAO is challenging, due both to a poor evidence base and the fact that spontaneous improvement in BMD is known to occur once pregnancy and lactation are complete. Bisphosphonates, denosumab and teriparatide have all been used in individual patients, but the data supporting their use are currently limited.

Drug therapy for osteoporosis in older adults

The goal of osteoporosis management is to prevent fractures. Several pharmacological agents are available to lower fracture risk, either by reducing bone resorption or by stimulating bone formation. Bisphosphonates are the most widely used anti-resorptives, reducing bone turnover markers to low premenopausal concentrations and reducing fracture rates (vertebral by 50-70%, non-vertebral by 20-30%, and hip by ~40%). Bisphosphonates bind avidly to bone mineral and have an offset of effect measured in months to years. Long term, continuous use of oral bisphosphonates is usually interspersed with drug holidays of 1-2 years, to minimise the risk of atypical femoral fractures. Denosumab is a monoclonal antibody against RANKL that potently inhibits osteoclast development and activity. Denosumab is administered by subcutaneous injection every 6 months. Anti-fracture effects of denosumab are similar to those of the bisphosphonates, but there is a pronounced loss of anti-resorptive effect from 7 months after the last injection, which can result in clusters of rebound vertebral fractures. Two classes of anabolic drugs are now available to stimulate bone formation. Teriparatide and abaloparatide both target the parathyroid hormone-1 receptor, and are given by daily subcutaneous injection for up to 2 years. Romosozumab is an anti-sclerostin monoclonal antibody that stimulates bone formation and inhibits resorption. Romosozumab is given as monthly subcutaneous injections for 1 year. Head-to-head studies suggest that anabolic agents have greater anti-fracture efficacy and produce larger increases in bone density than anti-resorptive drugs. The effects of anabolic agents are transient, so transition to anti-resorptive drugs is required. The optimal strategy for cycling anabolics, anti-resorptives, and off-treatment periods remains to be determined.

Comparative Fracture Risk During Osteoporosis Drug Holidays After Long-Term Risedronate Versus Alendronate Therapy : A Propensity Score-Matched Cohort Study

BACKGROUND

An osteoporosis drug holiday is recommended for most patients after 3 to 5 years of therapy. Risedronate has a shorter half-life than alendronate, and thus the residual length of fracture protection may be shorter.

OBJECTIVE

To examine the comparative risks of drug holidays after long-term (≥3 years) risedronate versus alendronate therapy.

DESIGN

Population-based, matched, cohort study.

SETTING

Province-wide health care administrative databases providing comprehensive coverage to Ontario residents aged 65 years or older between November 2000 and March 2020.

PATIENTS

Persons aged 66 years or older who had long-term risedronate therapy and a drug holiday were matched 1:1 on propensity score to those who had long-term alendronate therapy and a drug holiday.

MEASUREMENTS

The primary outcome was hip fracture within 3 years after a 120-day ascertainment period. Secondary analyses included shorter follow-up and sex-specific estimates. Cox proportional hazards models were used to estimate hazard ratios (HRs) for fracture risk between groups.

RESULTS

A total of 25 077 propensity score-matched pairs were eligible (mean age, 81 years; 81% women). Hip fracture rates were higher among risedronate than alendronate drug holidays (12.4 and 10.6 events, respectively, per 1000 patient-years; HR, 1.18 [95% CI, 1.04 to 1.34]; 915 total hip fractures). The association was attenuated when any fracture was included as the outcome (HR, 1.07 [CI, 1.00 to 1.16]) and with shorter drug holidays (1 year: HR, 1.03 [CI, 0.85 to 1.24]; 2 years: HR, 1.14 [CI, 0.96 to 1.32]).

LIMITATION

Analyses were limited to health care administrative data (potential unmeasured confounding), and some secondary analyses contained few events.

CONCLUSION

Drug holidays after long-term therapy with risedronate were associated with a small increase in risk for hip fracture compared with alendronate drug holidays. Future research should examine how best to mitigate this risk.

PRIMARY FUNDING SOURCE

Canadian Institutes of Health Research.

Osteonecrosis development by tooth extraction in zoledronate treated mice is inhibited by active vitamin D analogues, anti-inflammatory agents or antibiotics

Invasive dental treatment such as tooth extraction following treatment with strong anti-bone resorptive agents, including bisphosphonates and denosumab, reportedly promotes osteonecrosis of the jaw (ONJ) at the extraction site, but strategies to prevent ONJ remain unclear. Here we show that in mice, administration of either active vitamin D analogues, antibiotics or anti-inflammatory agents can prevent ONJ development induced by tooth extraction during treatment with the bisphosphonate zoledronate. Specifically, tooth extraction during treatment with zoledronate induced osteonecrosis in mice, but administration of either 1,25(OH)2D3 or ED71, both active vitamin D analogues, significantly antagonized osteonecrosis development, even under continuous zoledronate treatment. 1,25(OH)2D3 or ED71 administration also significantly inhibited osteocyte apoptosis induced by tooth extraction and bisphosphonate treatment. Administration of either active vitamin D analogue significantly inhibited elevation of serum inflammatory cytokine levels in mice in response to injection of lipopolysaccharide, an infection mimetic. Furthermore, administration of either anti-inflammatory or antibiotic reagents significantly blocked ONJ development following tooth extraction and zoledronate treatment. These findings suggest that administration of active vitamin D, anti-inflammatory agents or antibiotics could prevent ONJ development induced by tooth extraction in patients treated with zoledronate.

Discontinuation of bisphosphonates in seniors: a systematic review on health outcomes

PURPOSE

Bisphosphonates are used to treat osteoporosis. Despite their benefits on bone mineral density (BMD) and fractures, they have shown adverse effects, sometimes severe, during chronic use. Taken for several years, they achieve long-term bone retention, making deprescribing feasible. This review aimed to synthesize evidence on the success and health outcomes of deprescribing of bisphosphonates in seniors, aged over 60 years.

METHODS

The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, including articles in English, French, or German published before July 2020. Eligible studies included seniors having discontinued bisphosphonates and reported on health outcomes; some allowed meta-analyses on fracture risk.

RESULTS

The review included 9 RCTs and 9 cohort studies of moderate quality. Bisphosphonates were discontinued after 2 to 7 years of use, and BMD or fractures were assessed during follow-up of 0.5 to 5 years. A significant reduction in BMD after discontinuation was observed in 9 of 10 studies. Results on fracture risk after discontinuation are mitigated: 6 RCT extensions showed no increase in the risk of any osteoporotic fractures after discontinuation. Meta-analyses including 4 RCTs showed an increased odds ratio of vertebral fractures of 2.04 (95% CI, 1.39-2.99) among discontinuers. Results from 2 large cohort studies showed no increased risks of any osteoporotic or vertebral fractures, while 2 studies found increased fracture risks.

CONCLUSION

Bisphosphonates have successfully been discontinued low overall fracture risk after at least 3 years of use, but a risk for decreased BMD and increased vertebral fractures remained.

Early changes in bone turnover and bone mineral density after discontinuation of long-term oral bisphosphonates: a post hoc analysis

This post hoc analysis of a randomized, double-blind study of postmenopausal women with osteoporosis found that there were early increases in bone turnover markers and decreases in bone mineral density after discontinuation of long-term alendronate. These findings might help guide treatment decisions, including monitoring after alendronate withdrawal.

INTRODUCTION

The short-term effects of discontinuing long-term bisphosphonates are poorly characterized. This post hoc analysis investigated 1-12-month changes in bone mineral density (BMD) and bone turnover markers (BTM) after alendronate (ALN) discontinuation.

METHODS

Data were from a randomized, double-blind trial of MK-5442 (calcium-sensing receptor antagonist) following oral bisphosphonates, with placebo and continued ALN controls ( ClinicalTrials.gov NCT00996801). Postmenopausal women with osteoporosis had received oral bisphosphonate (≥ 3-4 preceding years; ALN for the 12 months pre-screening), continuing on ALN 70 mg/week (n = 87) or placebo (n = 88).

RESULTS

At 12 months, least-squares mean percent changes from baseline BMD (placebo vs. ALN) were lumbar spine (LS): - 0.36 vs. 1.29, total hip: - 1.44 vs. 0.46, and femoral neck (FN): - 1.26 vs. - 0.08 (all P < 0.05). BTM levels increased by 1-3 months, to 12 months, with placebo vs. ALN (P < 0.001). FN BMD decline was greater in the placebo subgroup with higher urinary N-terminal cross-linked telopeptides of type I collagen/creatinine [uNTx/Cr] (P < 0.01), and higher serum N-terminal pro-peptide of type 1 collagen [P1NP] levels (P < 0.05), at baseline. There was a trend toward greater FN BMD loss with higher BTM levels at 3 and/or 6 months. Younger age and higher LS BMD at baseline were associated with greater LS BMD loss at 12 months (P = 0.04 and < 0.01, respectively); higher baseline FN BMD predicted greater FN BMD loss (P = 0.04).

CONCLUSION

Early changes in BTM levels and BMD were observed after discontinuation of long-term ALN. Further characterization of factors associated with patients' risk of bone loss upon bisphosphonate discontinuation is warranted.

Risks vs. benefits of switching therapy in patients with postmenopausal osteoporosis

Introduction: Osteoporosis is characterized by the fragility of bones, leading to fractures and, consequently, the deterioration of functional capacity and quality of life. Postmenopausal women, in particular, are prone to osteoporosis and often require anti-osteoporosis treatment. In the last few decades, various anti-osteoporosis drugs have been approved for clinical use. In an aging society, osteoporosis cannot be treated using a single agent; therefore, switching therapy is an important treatment strategy.Areas covered: This review covers switching therapy in patients with postmenopausal osteoporosis. It's extremely important to understand the characteristics of each drug including; limitations on the duration of use, side effects due to long-term use (such as atypical femur fracture and osteonecrosis of the jaw) or discontinuation (such as rebound phenomenon), compliance, and ability to prevent fractures. We review and summarize the risks and benefits of switching therapy.Expert opinion: When switching therapy, the order of drug administration is important. Routine monitoring should be continued after switching treatments. We recommend first using osteoanabolic agents in postmenopausal women with severe osteoporosis. In addition, identifying predictors of the efficacy and side effects of treatment may help prevent the inappropriate use of drugs for the treatment of osteoporosis.

The predictive value of bone turnover markers during discontinuation of alendronate: the PROSA study

In patients discontinuing ALN after a median of 7.0 years (range 5.0-20.0 years), BMD decreased, and bone turnover markers increased within the premenopausal reference range over 2 years. Increased p-CTX after 3 months was associated with greater bone loss at the hip confirming that maintenance of BMD is dependent on continued suppression of bone turnover.

INTRODUCTION

It is unknown how to monitor patients discontinuing alendronate (ALN) after more than 5 years. We investigated if BTM measured before or during treatment discontinuation with ALN predict bone loss after 1 or 2 years.

METHODS

PROSA was a cohort study conducted at Aarhus University Hospital including postmenopausal women and men above 50 years treated with ALN ≥ 5 years who had osteopenia at the hip and BMD T-score at the lumbar spine > - 4. ALN was discontinued and BTMs were measured at baseline, months (M) 1, 3, 6, and 12, and DXA was performed at baseline, M6, and M12. We extended the study and measured BTMs and performed DXA at M24. The primary endpoint was if changes in p-CTX at M3 or M6 predict changes in THBMD after 1 year ( Clinicaltrials.gov : NCT03051620).

RESULTS

We enrolled 136 participants discontinuing ALN after a median of 7.0 years (range 5.0-20.0 years) in PROSA and 124 participants in PROSA Extension. There was a significant decrease in LSBMD - 0.74% ± 0.27, THBMD - 2.65% ± 0.39, FNBMD - 2.35% ± 0.33, and trabecular bone score - 0.97% ± 0.35 and an increase in p-CTX by 61.1% ± 4.7 (p < 0.05 for all) after 24 months. Increase in p-CTX at M3 was associated with bone loss at the hip sites at M12 and M24.

CONCLUSION

In patients discontinuing ALN, BMD decreased significantly and BTMs increased within the reference range over 2 years. An increase in p-CTX after 3 months was associated with greater bone loss at the hip confirming that maintenance of BMD during treatment discontinuation is dependent on continued suppression of bone turnover.

[Long-term treatment concepts for osteoporosis]

Die Notwendigkeit einer Langzeittherapie bei Osteoporose, eine teils eingeschränkte Compliance, aber auch die Möglichkeit von erheblichen Nebenwirkungen bei einer pharmakologischen Osteoporosetherapie beschäftigen sowohl die medizinischen Richtlinien als auch die Betroffenen in vielfacher Weise. In dieser Übersicht wird auf den Stand der zur Verfügung stehenden Osteoporosepharmazeutika und die aktuellen wissenschaftlich fundierten Grundlagen einer langjährigen Anwendung, das potenzielle Monitoring und mögliche Therapieänderungen mit dem spezifischen Augenmerk auf künftige Entwicklungen eingegangen.

Duration of Bisphosphonate Drug Holidays in Osteoporosis Patients: A Narrative Review of the Evidence and Considerations for Decision-Making

Bisphosphonates are first-line therapy for osteoporosis, with alendronate, risedronate, and zoledronate as the main treatments used globally. After one year of therapy, bisphosphonates are retained in bone for extended periods with extended anti-fracture effects after discontinuation. Due to this continued fracture protection and the potential for rare adverse events associated with long-term use (atypical femoral fractures and osteonecrosis of the jaw), a drug holiday of two to three years is recommended for most patients after long-term bisphosphonate therapy. The recommendation for a drug holiday up to three years is derived primarily from extensions of pivotal trials with alendronate and zoledronate and select surrogate marker studies. However, certain factors may modify the duration of bisphosphonate effects on a drug holiday and warrant consideration when determining an appropriate time off-therapy. In this narrative review, we recall what is currently known about drug holidays and discuss what we believe to be the primary considerations and areas for future research regarding drug holiday duration: total bisphosphonate exposure, type of bisphosphonate used, bone mineral density and falls risk, and patient sex and body weight.

The Efficacy and Safety of Bisphosphonates for Osteoporosis in Women Older Than 65 Years: A Meta-Analysis

BACKGROUND

Osteoporosis presents a major threat to the health of women older than 65 years. Bisphosphonates (BPs) are now the principal class of medications for osteoporosis.

OBJECTIVE

To evaluate the efficacy and safety of BPs in women older than 65 years.

METHODS

A comprehensive search in the PubMed, EMBASE, Web of Science and Cochrane Central databases was undertaken for randomized controlled trials (RCTs) on the efficacy and safety of BPs in women older than 65 years. The primary outcome measures were the change in bone mass density (BMD), serum bone turnover marker levels, fracture rate and the adverse effect (AE) rate. The final search was performed in August 2019.

RESULTS

Seven RCTs were included. A total of 23287 patients met the inclusion criteria. BPs significantly increased the BMD of the posteroanterior (PA) spine, lateral spine and femoral neck, and reduced the fracture, vertebrate fracture and hip fracture rates in women older than 65 years. In addition, BPs increased the risks for pyrexia, myalgia, arthralgia, headache and influenza-like symptoms and had no statistical effect on any AEs, any serious AEs, discontinuation due to AEs, oesophagitis, any upper gastrointestinal adverse event, atrial fibrillation and myocardial infarction occurrence in women older than 65 years. Finally, intravenous BPs reduced hip fracture risk but increased AEs in women older than 65 years.

CONCLUSION

Despite the fact that AEs significantly increased after drug delivery, BPs are highly effective and safe for managing osteoporosis in women older than 65 years. Zoledronic acid caused an increased rate of AEs in women older than 65 years, but these AEs seemed to be mild to moderate. In addition, the hip fracture rate in women older than 80 years old treated with BPs was different than that in the other included patients. Therefore, doctors may prescribe BPs for women older than 65 years in order to increase BMD, and AEs and hip fractures in women older than 80 years should be given attention.

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.

Sustained anti-osteoporotic action of risedronate compared to anti-RANKL antibody following discontinuation in ovariectomized mice

Bisphosphonates and the anti-receptor activator of nuclear factor-kappa B ligand (RANKL) antibody denosumab are effective anti-resorptive drugs commonly prescribed for osteoporosis. Both drugs may, however, have intolerable side effects; so, it is critical to examine their residual efficacy such as maintenance of bone mass following cessation. Therefore, we compared the changes in bone histology following discontinuation of the aminobisphosphonate risedronate and anti-RANKL antibody in ovariectomized (OVX) mice. Twelve-week-old female C57BL/6 N mice were OVX or sham operated. Four weeks after surgery, mice were treated with vehicle, a single injection of anti-RANKL antibody (5 mg/kg), or risedronate (5 μg/kg/day, s.c.) for 4 weeks (the treatment period), followed by vehicle treatment for an additional 4 weeks (discontinuation period). The lumbar spine and proximal tibia were evaluated by micro-computed tomography. In addition, the lumbar spine, proximal tibia, and the femoral shaft were examined by bone histomorphometry. After 4 weeks of discontinuation, OVX mice initially treated with the anti-RANKL antibody exhibited a trend of bone loss associated with increased turnover in both trabecular and cortical bones, although the difference was not significant. By contrast, OVX mice treated with risedronate exhibited maintained or even increased bone mass and suppressed bone turnover. Patients discontinuing denosumab should be carefully monitored for recurrent osteoporosis symptoms, and a replacement drug should be considered.

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Bone mass and suppression of turnover were maintained after stopping bisphophonates.

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Bone turnover was rapidly increased after discontinuation of anti-RANKL antibody.

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Periosteal bone formation was maintained after administration of antiresorptive drugs.

Overview of treatment approaches to osteoporosis

Efficient therapies are available for the treatment of osteoporosis. Anti-resorptive therapies, including bisphosphonates and denosumab, increase bone mineral density (BMD) and reduce the risk of fractures by 20-70%. Bone-forming or dual-action treatments stimulate bone formation and increase BMD more than the anti-resorptive therapies. Two studies have demonstrated that these treatments are superior to anti-resorptives in preventing fractures in patients with severe osteoporosis. Bone-forming or dual-action treatments should be followed by anti-resorptive treatment to maintain the fracture risk reduction. The BMD gains seen with bone-forming and dual-action treatments are greater in treatment-naïve patients compared to patients pretreated with anti-resorptive treatments. However, the antifracture efficacy seems to be preserved. Treatment failure will often lead to switch of treatment from orally to parentally administrated anti-resorptives treatment or from anti-resorptive to bone-forming or dual-action treatment. Osteoporosis is a chronic condition and therefore needs a long-term management plan with a personalized approach to treatment. LINKED ARTICLES: This article is part of a themed issue on The molecular pharmacology of bone and cancer-related bone diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.9/issuetoc.

Rare adverse effects of bisphosphonate therapy

PURPOSE OF REVIEW

To give an update on the latest developments regarding rare adverse effects of bisphosphonate therapy.

RECENT FINDINGS

Recent studies covering osteonecrosis of the jaw (ONJ) and atypical femoral fractures (AFFs) provided several updates to the literature. Identification of ONJ in large population databases is a challenge but based on one systematic review, the ICD-10 diagnosis code K10.2 (inflammatory conditions of the jaw) seems to be the most commonly used code for this condition. Duration of bisphosphonate therapy was determined to be an important predictor of AFFs. Appropriate duration of therapy followed by a timely drug holiday was shown to be the best strategy for improving bone mineral density and reducing fracture risk, while minimizing risk of rare adverse effects of therapy. The utility of bone turnover markers as a monitoring tool during drug holidays needs to be further investigated.

SUMMARY

ONJ and AFFs are two of the rare adverse effects associated with bisphosphonate therapy. Population-level trends of bisphosphonate use suggest a decline in prescriptions, pointing to broad fears of these side effects. Careful patient evaluation, duration of bisphosphonate therapy, and use of drug holidays can help limit any risk associated with therapy.

Effectiveness of monthly intravenous ibandronate on the low responders to oral bisphosphonate: the MOVEMENT study

The MOVEMENT study was designed to assess the effectiveness of monthly intravenous ibandronate on bone mineral density (BMD) in daily clinical practice in Japanese patients with primary osteoporosis whose lumbar spine BMD did not increase despite oral bisphosphonate therapy. This study was a multicenter, prospective, interventional study (52 sites; August 2015 to March 2018). Patients aged ≥ 50 years with primary osteoporosis, evaluated as low responders to oral bisphosphonate treatment for 1-3 years, continued on their existing oral bisphosphonate or switched to monthly intravenous ibandronate (1 mg) for 12 months. The primary endpoint was change in lumbar spine BMD from baseline to 12 months in the intravenous ibandronate group (IV IBN). A total of 240 and 141 patients were enrolled in the IV IBN and oral bisphosphonate groups (OBP), respectively. At 12 months, a significant increase in mean percent change from baseline in lumbar spine BMD was observed in the IV IBN (2.70%). This change was also significant at 6 months (1.92%). Similarly, the change in total hip BMD showed a significant increase at 12 months (0.78%). In the IV IBN, the responder rate, percentage of patient whose change from baseline of lumbar spine BMD has greater than 0%, for lumbar spine BMD was high at both 6 (72.3%, 141/195 patients) and 12 (78.0%, 145/186 patients) months. No new safety concerns were observed in either treatment group. Treatment with intravenous ibandronate significantly increased lumbar spine BMD without any new safety concerns in Japanese patients with osteoporosis who showed low response to existing oral bisphosphonates.

Repeating Measurement of Bone Mineral Density when Monitoring with Dual-energy X-ray Absorptiometry: 2019 ISCD Official Position

Bone mineral density (BMD) can be measured at multiple skeletal sites using various technologies to aid clinical decision-making in bone and mineral disorders. BMD by dual-energy X-ray absorptiometry (DXA) has a critical role in predicting risk of fracture, diagnosis of osteoporosis, and monitoring patients. In clinical practice, DXA remains the most available and best validated tool for monitoring patients. A quality baseline DXA scan is essential for comparison with all subsequent scans. Monitoring patients with serial measurements requires technical expertise and knowledge of the least significant change in order to determine when follow-up scans should be repeated. Prior ISCD Official Positions have clarified how and when repeat DXA is useful as well as the interpretation of results. The 2019 ISCD Official Positions considered new evidence and clarifies if and when BMD should be repeated. There is good evidence showing that repeat BMD measurement can identify people who experience bone loss, which is an independent predictor of fracture risk. There is good evidence showing that the reduction in spine and hip fractures with osteoporosis medication is proportional to the change in BMD with treatment. There is evidence that measuring BMD is useful following discontinuation of osteoporosis treatment. There is less documentation addressing the effectiveness of monitoring BMD to improve medication adherence, whether monitoring of BMD reduces the risk of fracture, or effectively discriminates patients who should and should not recommence treatment following an interruption of medication. Further research is needed in all of these areas.

Fracture risk following intermission of osteoporosis therapy

Given the widespread practice of recommending drug holidays, we reviewed the impact of medication discontinuation of two common anti-osteoporosis therapies (bisphosphonates and denosumab). Trial evidence suggests the risk of new clinical fractures, and vertebral fracture increases when osteoporosis treatment with bisphosphonates or denosumab is stopped.

INTRODUCTION

The aim of this paper was to review the available literature to assess what evidence exists to inform clinical decision-making with regard to drug holidays following treatment with bisphosphonates (BiP) or denosumab.

METHODS

Systematic review.

RESULTS

Differing pharmacokinetics lead to varying outcomes on stopping therapy. Prospective and retrospective analyses report that the risk of new clinical fractures was 20-40% higher in subjects who stopped BiP treatment, and vertebral fracture risk was approximately doubled. Rapid bone loss has been well described following denosumab discontinuation with an incidence of multiple vertebral fractures around 5%. Studies have not identified risk factors for fracture after stopping treatment other than those that provide an indication for treatment (e.g. prior fracture and low BMD). Studies that considered long-term continuation did not identify increased fracture risk, and reported only very low rates of adverse skeletal events such as atypical femoral fracture.

CONCLUSIONS

The view that patients on long-term treatment with bisphosphonates or denosumab should always be offered a drug holiday is not supported by the existing evidence. Different pharmacokinetic properties for different therapies require different strategies to manage drug intermission. In contrast, long-term treatment with anti-resorptives is not associated with increased risk of fragility fractures and skeletal adverse events remain rare.

Pharmacological Management of Osteoporosis in Postmenopausal Women: An Endocrine Society* Clinical Practice Guideline

OBJECTIVE

The objective is to formulate clinical practice guidelines for the pharmacological management of osteoporosis in postmenopausal women.

CONCLUSIONS

Evidence from clinical trials and insights from clinical experience with pharmacologic therapies for osteoporosis were critically evaluated in formulating this guideline for the management of postmenopausal osteoporosis. Patient preferences, data on adherence and persistence, and risks and benefits from the patient and provider perspectives were also considered in writing committee deliberations. A consensus by the Writing Committee members was achieved for four management principles: (i) The risk of future fractures in postmenopausal women should be determined using country-specific assessment tools to guide decision-making. (ii) Patient preferences should be incorporated into treatment planning. (iii) Nutritional and lifestyle interventions and fall prevention should accompany all pharmacologic regimens to reduce fracture risk. (iv) Multiple pharmacologic therapies are capable of reducing fracture rates in postmenopausal women at risk with acceptable risk-benefit and safety profiles.

Pregnancy-associated osteoporosis: a UK case series and literature review

Mini Abstract: Pregnancy-associated osteoporosis (PAO) is a rare syndrome affecting women during late pregnancy and the early postpartum period. We set out to review the clinical features of ten cases of PAO from a single UK centre. Patients had attended the Royal National Hospital for Rheumatic Diseases, Bath (RNHRD) between January 2000 and June 2016. The principal criterion for inclusion was the occurrence of low trauma fractures either during pregnancy or the immediate post-partum period. Data were obtained from retrospective review of medical notes. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (Hologic ®Discovery system) at the lumbar spine and hip. Data pertaining to the pregnancy, as well as type and duration of treatment received, were reviewed. All ten cases presented with vertebral fractures. In four patients, no risk factors for fracture other than pregnancy or breastfeeding could be identified. Four patients were found to have vitamin D insufficiency at the time of diagnosis, and a further two patients had received treatment with low molecular weight heparin (LMWH). In one case, further investigation led to a diagnosis of osteogenesis imperfecta (OI) confirmed on genetic testing. In terms of treatment, eight out of the ten patients in this series received a bisphosphonate, most commonly risedronate due to its relatively short skeletal retention time. Clinicians should be aware of PAO, a rare but recognised complication of pregnancy. The condition should be especially considered in women presenting with new onset back pain in pregnancy or the postpartum period.

Clinical utility of bone turnover markers in monitoring the withdrawal of treatment with oral bisphosphonates in postmenopausal osteoporosis

Bone markers may be useful to monitor response to treatment withdrawal in osteoporosis. We used two criteria for investigating the change in BTMs after withdrawal of bisphosphonate treatment. A larger increase in BTMs was associated with greater bone loss. Bone markers may be useful in monitoring of patients taking a pause from treatment.

INTRODUCTION

Measurement of bone turnover markers (BTMs) may be useful to monitor offset of treatment with bisphosphonates (BP) in osteoporosis. We assessed the effect of withdrawal of BP treatment by comparing the changes in BTMs and total hip (TH) bone density (BMD).

METHODS

We studied postmenopausal osteoporotic women who had completed a randomised study of three oral BPs. After 2 years of treatment, participants with BMD T-score > - 2.5 and in whom it was considered clinically appropriate to discontinue treatment, were invited to participate in a further 2-year observational study. Biochemical response was assessed using BTMs (CTX and PINP) with offset being defined by two criteria: (1) an increase greater than the least significant change (LSC) and (2) an increase above the reference mean value.

RESULTS

Fifty women completed the study. At 48 weeks after stopping BPs, CTX was greater than the LSC for 66% of women and PINP 72%; CTX was above the reference mean for 64% of women and PINP 42%. The decrease in THBMD was greater for women with the largest increase in BTM compared to those with continued suppression (mean difference for CTX was - 2.98%, 95%CI - 4.75 to - 1.22, P < 0.001, PINP - 2.25%, 95% CI - 4.46 to - 0.032, P = 0.046).

CONCLUSION

The measurement of BTM after withdrawal of BPs is potentially useful to evaluate patients that are taking a pause from treatment. An increase in BTMs more than the LSC and/or reference mean reflects loss of treatment effect and identifies patients that are likely to have a decrease in BMD. Such changes could provide an indication for reintroduction of treatment.

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.