Effects of two intermittent alendronate regimens in the prevention or treatment of postmenopausal osteoporosis

A network meta-analysis on the short-term efficacy and adverse events of different anti-osteoporosis drugs for the treatment of postmenopausal osteoporosis

A network meta-analysis was conducted to compare the short-term efficacy and adverse events of different drugs for the treatment of postmenopausal osteoporosis (PMO), providing a more effective treatment for PMO. We initially searched through various databases like PubMed, Cochrane Library, and EMBASE from inception till October 2016. All randomized controlled trials (RCTs) of drugs for the treatment of PMO were included for direct and indirect comparison. A combination of direct and indirect evidence of different inhibitors of anti-diabetic drugs for treatment of PMO were considered for calculating the weighted mean difference (WMD) value or odd ratio (OR) value and to draw surface under the cumulative ranking (SUCRA) curves. Twenty-seven RCTs were ultimately incorporated into this network meta-analysis comprising of 48 200 patients suffering from PMO. The network meta-analysis revealed that compared with placebo, alendronate had better efficacy on improving bone mineral density (BMD) at lumbar spine, femoral neck, and total hip. Risedronate and raloxifene had relatively lower incidence of new vertebral fractures. The SUCRA analysis showed that alendronate had better efficacy on improving BMD, risedronate could significantly decrease the incidence of fresh fracture and bazedoxifene was relatively safe. The available evidence suggested that alendronate and risedronate might be the superior choices for the treatment of PMO, while bazedoxifene was a comparatively safer option for patients.

Analysis of Bone Alkaline Phosphatase as a Marker for the Diagnosis of Osteoporosis in Men under Androgen Ablation

The objective of this study was to evaluate the usefulness of serum determination of bone alkaline phosphatase (BAP) in the diagnosis of osteoporosis in men with prostate cancer under androgen ablation. Serum levels of BAP and bone mineral density (BMD) were assessed in 110 patients with non-metastatic, treated prostate cancer. Fifty-eight patients were under androgen deprivation during a period between two and 96 months and 52 had been submitted only to radical prostatectomy. Mean serum BAP was 11.8 ng/mL in patients with normal BMD, 16.7 ng/mL in patients with osteopenia (p. 0.058), and 19.3 ng/mL in patients with osteoporosis (p=0.044). The correlation between serum BAP and BMD was significant (p. 0.006) but with an index of only 0.26. Receiver operating characteristic analysis for the diagnosis of osteoporosis showed an area under the curve of 0.608. None of the cutoff points that provided specificities of 75%, 90% and 95% gave significant distributions. The positive and negative predictive values as well as the odds ratios were not of any clinical usefulness. We conclude that serum BAP should not be considered a good marker for the diagnosis of osteoporosis in men with prostate cancer. Therefore, BAP serum determination cannot replace bone densitometry as a diagnostic tool.

Synthesis of composite magnetic nanoparticles Fe3O4 with alendronate for osteoporosis treatment

Osteoporosis is a result of imbalance between bone formation by osteoblasts and resorption by osteoclasts (OCs). In the present study, we investigated the potential of limiting the aggravation of osteoporosis by reducing the activity of OCs through thermolysis. The proposed method is to synthesize bisphosphonate (Bis)-conjugated iron (II, III) oxide (Fe₃O₄) nanoparticles and incorporate them into OCs. The cells should be subsequently exposed to radiofrequency (RF) to induce thermolysis. In this study, particles of Fe₃O₄ were first synthesized by chemical co-precipitation and then coated with dextran (Dex). The Dex/Fe₃O₄ particles were then conjugated with Bis to form Bis/Dex/Fe₃O₄. Transmission electron microscopy revealed that the average diameter of the Bis/Dex/Fe₃O₄ particles was ~20 nm. All three kinds of nanoparticles were found to have cubic inverse spinel structure of Fe₃O₄ by the X-ray diffraction analysis. Fourier transform infrared spectroscopy confirmed that the Dex/Fe₃O₄ and Bis/Dex/Fe₃O₄ nanoparticles possessed their respective Dex and Bis functional groups, while a superconducting quantum interference device magnetometer measured the magnetic moment to be 24.5 emu. In addition, the Bis/Dex/Fe₃O₄ nanoparticles were fully dispersed in double-distilled water. Osteoblasts and OCs were individually cultured with the nanoparticles, and an MTT assay revealed that they were non-cytotoxic. An RF system (42 kHz and 450 A) was used to raise the temperature of the nanoparticles for 20 minutes, and the thermal effect was found to be sufficient to destroy OCs. Furthermore, in vivo studies verified that nanoparticles were indeed magnetic resonance imaging contrast agents and that they accumulated after being injected into the body of rats. In conclusion, we developed a water-dispersible magnetic nanoparticle that had RF-induced thermogenic properties, and the results indicated that the Bis/Dex/Fe₃O₄ nanoparticle had the potential for controlling osteoporosis.

Intermittent minodronic acid treatment with sufficient bone resorption inhibition prevents reduction in bone mass and strength in ovariectomized rats with established osteopenia comparable with daily treatment

This study examined and compared the effects of four-week intermittent and daily administrations of minodronic acid, a highly potent nitrogen-containing bisphosphonate, on bone mineral density (BMD), bone strength, bone turnover, and histomorphometry on established osteopenia in ovariectomized (OVX) rats. Fourteen-week-old female F344 rats were OVX or sham-operated. At 12 weeks post surgery, minodronic acid was orally administered once every 4 weeks at 0.2, 1, and 5 mg/kg and once daily at 0.006, 0.03, and 0.15 mg/kg for 12 months. The total dosing amount was comparable between the two dosing regimens. The levels of urinary deoxypyridinoline and serum osteocalcin were measured to assess bone turnover. BMD as assessed via dual-energy X-ray absorptiometry, bone structure and dynamical changes in vertebral trabecula and biomechanical properties were measured ex vivo at 12 months to assess bone content and material properties. Minodronic acid dose-dependently ameliorated the decrease in BMD of lumbar vertebrae and the femur in both treatment regimens similarly. Minodronic acid suppressed elevated urinary levels of deoxypyridinoline, a bone resorption marker, and reduced the serum levels of osteocalcin, a bone formation marker. In the mechanical test at 12 months of treatment, minodronic acid dose-dependently ameliorated the reduction in bone strength in femur and vertebral body. There is no significant difference in parameters between the two regimens except maximal load of lower doses in lumbar vertebral body and absorption energy of middle doses in femur. With these parameters with significant differences, values of the intermittent regimen were significantly lower than that of daily repeated regimen. Bone histomorphometric analysis of the lumbar vertebral body showed that minodronic acid significantly ameliorated the decrease in bone mass, trabecular thickness and number, and the increase in trabecular separation, bone resorption indices (Oc.S/BS and N.Oc/BS), and bone formation indices (BFR/BS, MAR and OV/BV) in both regimens. Minodronic acid suppressed OVX-induced increases in bone turnover at the tissue level and ameliorated all structural indices, thereby improving the deterioration of bone quality under osteoporotic disease conditions regardless of the regimen. In conclusion, a four-week intermittent treatment of minodronic acid suppressed increased bone resorption as daily treatment when considering the total administered dose in OVX rats with established osteopenia. The improvement of microarchitectural destruction in low dose of intermittent treatment was weaker than that observed in a daily repeated regimen; however the effects of high and middle doses of intermittent treatment were equivalent to that observed in daily repeated regimen accompanied by sufficient bone resorption inhibition in rats. These findings suggest that minodronic acid at an appropriate dose in an intermittent regimen may be as clinically useful in osteoporosis therapy as in daily treatment.

Effect of low-dose alendronate treatment on bone mineral density and bone turnover markers in Chinese postmenopausal women with osteopenia and osteoporosis

OBJECTIVE

The aim of this study was to evaluate the effect of low-dose alendronate (ALN) treatment on bone mineral density (BMD) and bone turnover markers in Chinese postmenopausal women with osteopenia and osteoporosis.

METHODS

This study was a large-sample, randomized, open-label, prospective, multicenter, clinical trial with a 12-month follow-up. A total of 639 postmenopausal women (aged 62.2 ± 7.0 y) with osteopenia or osteoporosis were randomized into two groups: low-dose ALN (70 mg every two weeks) and standard-dose ALN (70 mg weekly). All patients were also supplemented with calcium (600 mg) and vitamin D3 (125 IU) daily. BMD (measured by dual-energy x-ray absorptiometry; Hologic and Lunar) and levels of serum bone turnover markers (bone resorption marker, carboxy-telopeptide of type I collagen; bone formation marker, alkaline phosphatase) were assessed at baseline and at 3, 6, and 12 months of treatment. BMD and bone turnover markers were compared between the baseline and the end of treatment, and the changes in BMD and bone turnover markers were also compared between the low-dose ALN group and the standard-dose ALN group.

RESULTS

No significant differences in age, years since menopause, body mass index, BMD, 25-hydroxy vitamin D level, and serum biochemical markers were found at baseline between the two dose groups. A total of 558 (87.3%) and 540 (84.5%) women completed the treatment at the 6th and 12th months, respectively. After the 12-month treatment, lumbar spine and hip BMD increased and serum bone turnover markers decreased significantly in both of the treatment groups (P < 0.01), and no differences in percentage changes in BMD at the lumbar spine, femoral neck, and hip were found between the low-dose group (5.60%, 3.87%, and 3.28%, respectively) and the standard-dose group (5.07%, 2.93%, and 3.80%, respectively; P > 0.05). However, levels of serum alkaline phosphatase and carboxy-telopeptide of type I collagen in the standard-dose group decreased moderately compared with those in the low-dose group (P < 0.05 and P < 0.01). The women tolerated the two doses of ALN quite well. Adverse effects were similar in the two groups.

CONCLUSIONS

Treatment with low-dose ALN (70 mg every two weeks) in women with postmenopausal osteopenia or osteoporosis effectively increases lumbar spine and hip BMD, similar to treatment with standard-dose ALN. Low-dose ALN may be a cost-effective and safe protocol for treating osteopenia or osteoporosis in Chinese women.

ACUTE AND SUBACUTE ORAL TOXICITY TESTS OF SINTERED DICALCIUM PYROPHOSPHATE ON OVARIECTOMIZED RATS FOR OSTEOPOROSIS TREATMENT

Sintered dicalcium pyrophosphate (SDCP) is a synthetic pyrophosphate analog that could be utilized in the treatment for osteoporosis. In this study, an ovariectomized rat model is used to evaluate the systematic toxicity of orally administered SDCP relative to its effects on bone mass. Ovariectomized Wistar rats were treated with experimental medication with different dosing strategies (0.5 mg/kg five days weekly, and 2.5 mg/kg once weekly) for once (acute oral toxicity test) and four weeks (subacute oral toxicity test) followed by recovery period. Clinical signs of toxicity, body weight, and food consumption of rats were recorded. Blood samples were collected for hematological and blood biochemical analyses. Rats were sacrificed for necropsy and major visceral organs were harvested for histological examination after the recovery period. Long bones of four limbs were harvested to evaluate the effects of SDCP on bone mass. Results showed that there was no change in clinical signs, body weight, food consumption, hematology, blood biochemistry, necropsy, and histological examination attributable to the oral administration with SDCP to rats during the dosing period and the recovery period. Analysis of bone ashes revealed that the ovariectomized rats ingested with 0.5 mg/kg SDCP five days weekly continually for four weeks increased bone mineral contents significantly. In the ovariectomized rats ingested with 2.5 mg/kg SDCP once weekly continually for four weeks, the bone mineral contents were increased to normal bone quality. This study indicates that the SDCP can increase bone mass in the ovariectomized rat with no deleterious effects.

Bisphosphonate effects on bone turnover, microdamage, and mechanical properties: what we think we know and what we know that we don't know

The bisphosphonates (BPs) have been useful tools in our understanding of the role that bone remodeling plays in skeletal health. The purpose of this paper is to outline what we know, and what is still unknown, about the role that BPs play in modulating bone turnover, how this affects microdamage accumulation, and ultimately what the effects of these changes elicited by BPs are to the structural and the material biomechanical properties of the skeleton. We know that BPs suppress remodeling site-specifically, probably do not have a direct effect on formation, and that the individual BPs vary with respect to speed of onset, duration of effect and magnitude of suppression. However, we do not know if these differences are meaningful in a clinical sense, how much remodeling is sufficient, the optimal duration of treatment, or how long it takes to restore remodeling to pre-treatment levels following withdrawal. We also know that suppression is intimately tied to microdamage accumulation, which is also site-specific, that BPs impair targeted repair of damage, and that they can reduce the energy absorption capacity of bone at the tissue level. However, the BPs are clearly effective at preventing fracture, and generally increase bone mineral density and whole bone strength, so we do not know whether these changes in damage accumulation and repair, or the mechanical effects at the tissue level, are clinically meaningful. The mechanical effects of BPs on the fatigue life of bone, or BP effects on bone subject to an impact, are entirely unknown. This paper reviews the literature on these topics, and identifies gaps in knowledge that can be addressed with further research.

Short-term effects of zoledronate on the histomorphology of osteoclast in young albino rats

The present study was conducted to histomorphometrically evaluate the effects of short-term administration of zoledronate, a third generation bisphosphonate, on the metaphysis of the proximal end of tibia in twenty day old male albino rats. Zoledronate (2.8 μg/kg body weight), was daily given subcutaneously for eleven days. The animals were sacrificed; tibiae were dissected out and decalcified in EDTA. Seven micron thick, serial longitudinal paraffin sections were stained with haematoxylin and eosin and examined under a Zeiss light microscope and Image Pro-Express Analyzer. In zoledronate treated rats, a significant increase (p<0.05) in the number of osteoclasts was observed both in the regions of primary spongiosa (zoledronate treated: 6.41 ± 0.30/mm(2), control: 2.90 ± 0.28/mm(2)) and secondary spongiosa (zoledronate treated: 49.58 ± 0.84/mm(2), control: 31.81 ± 2.02/mm(2)) along with a significant increase (p<0.05) in the length of the metaphyseal region as compared to the control group. The number of nuclei per osteoclast and area of the osteoclast also showed a significant increase (p<0.001; p<0.05 respectively) following the uptake of zoledronate. The findings in the present study, suggest that the osteoclasts are the primary sites of action of zoledronate resulting in decreased osteoclastic activity, which would account for the great increase in the number and size of inactive osteoclasts resulting in marked cancellous bone formation.

Primary hyperparathyroidism: an overview

Primary hyperparathyroidism is a common condition that affects 0.3% of the general population. Primary and tertiary care specialists can encounter patients with primary hyperparathyroidism, and prompt recognition and treatment can greatly reduce morbidity and mortality from this disease. In this paper we will review the basic physiology of calcium homeostasis and then consider genetic associations as well as common etiologies and presentations of primary hyperparathyroidism. We will consider emerging trends in detection and measurement of parathyroid hormone as well as available imaging modalities for the parathyroid glands. Surgical indications and approach will be reviewed as well as medical management of primary hyperparathyroidism with bisphosphonates and calcimimetics.

Changes in bone markers after once-weekly low-dose alendronate in postmenopausal women with moderate bone loss

BACKGROUND

High bone turnover, with bone resorption exceeding bone formation, is a major mechanism of postmenopausal osteoporosis. Therefore, inhibition of bone resorption is a rational approach for the prevention of bone loss. The objective of the current study was to determine the short-term efficacy of once-weekly low-dose alendronate in the prevention of bone loss, via bone turnover markers, in early postmenopausal Korean women with moderate bone loss.

METHODS

This study involved a 12-week, randomized, double-blind clinical trial that compared the effects of placebo with alendronate 20mg once weekly. All subjects received supplemental calcium 600 mg and vitamin D 400IU daily. We recruited 63 postmenopausal women (ranging from 50 to 65 years of age) with the lowest lumbar spine bone mineral density (BMD) at least 2.0 S.D. below the mean value for young healthy adults. BMD was measured at baseline and serum alkaline phosphatase (ALP), osteocalcin, C-terminal telopeptide of type I collagen (CTX), and osteoprotegerin (OPG) were measured at baseline and 12 weeks after treatment.

RESULTS

We randomly assigned 63 women to either placebo or alencronate 20 mg once a week for 3 months. Forty-nine women continued and completed all 3 months. After 3 months, bone resorption markers were significantly decreased in the alendronate group than in the placebo group: CTX -47.2% vs. 15% (p<0.01), ALP 1.6% vs. 25.9% (p=0.01), osteocalcin -29.2% vs. -13.6 (p=0.06). Women who received alendronate showed similar results to those who received placebo with regard to adverse events.

CONCLUSION

Once-weekly low-dose alendronate may be a cost-effective and safe method of suppressing bone turnover in early postmenopausal women with moderate bone loss.

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

BACKGROUND

Osteoporosis is an abnormal reduction in bone mass and bone deterioration leading to increased fracture risk. Alendronate belongs to the bisphosphonate class of drugs, which act to inhibit bone resorption by interfering with the activity of osteoclasts.

OBJECTIVES

To assess the efficacy of alendronate in the primary and secondary prevention of osteoporotic fractures in postmenopausal women.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE and EMBASE for relevant randomized controlled trials published between 1966 to 2007.

SELECTION CRITERIA

Women receiving at least one year of alendronate, for postmenopausal osteoporosis, were compared to those receiving placebo and/or concurrent calcium/vitamin D. The outcome was fracture incidence.

DATA COLLECTION AND ANALYSIS

We undertook study selection and data abstraction in duplicate. We performed meta-analysis of fracture outcomes using relative risks and a > 15% relative change was considered clinically important. We assessed study quality through reporting of allocation concealment, blinding and withdrawals.

MAIN RESULTS

Eleven trials representing 12,068 women were included in the review. Relative (RRR) and absolute (ARR) risk reductions for the 10 mg dose were as follows. For vertebral fractures, a significant 45% RRR was found (RR 0.55, 95% CI 0.45 to 0.67). This was significant for both primary prevention, with 45% RRR (RR 0.55, 95% CI 0.38 to 0.80) and 2% ARR, and secondary prevention with 45% RRR (RR 0.55, 95% CI 0.43 to 0.69) and 6% ARR. For non-vertebral fractures, a significant 16% RRR was found (RR 0.84, 95% CI 0.74 to 0.94). This was significant for secondary prevention, with 23% RRR (RR 0.77, 95% CI 0.64 to 0.92) and 2% ARR, but not for primary prevention (RR 0.89, 95% CI 0.76 to 1.04). There was a significant 40% RRR in hip fractures (RR 0.60, 95% CI 0.40 to 0.92), but only secondary prevention was significant with 53% RRR (RR 0.47, 95% CI 0.26 to 0.85) and 1% ARR. The only significance found for wrist was in secondary prevention, with a 50% RRR (RR 0.50 95% CI 0.34 to 0.73) and 2% ARR. For adverse events, we found no statistically significant differences in any included study. However, observational data raise concerns regarding potential risk for upper gastrointestinal injury and, less commonly, osteonecrosis of the jaw.

AUTHORS' CONCLUSIONS

At 10 mg per day, both clinically important and statistically significant reductions in vertebral, non-vertebral, hip and wrist fractures were observed for secondary prevention ('gold' level evidence, www.cochranemsk.org). We found no statistically significant results for primary prevention, with the exception of vertebral fractures, for which the reduction was clinically important ('gold' level evidence).

Changes in bone remodelling and antifracture efficacy of intermittent bisphosphonate therapy: implications from clinical studies with ibandronate

Bisphosphonates reduce the rate of bone resorption and bone remodelling. Given daily, they decrease the risk of fractures in postmenopausal osteoporosis. When bisphosphonates were given at extended drug-free intervals this antifracture efficacy was generally not seen. This may be due to the different pattern of bone remodelling changes. Data from randomised clinical studies of ibandronate, given orally or intravenously, at different doses and for variable time intervals to women with osteoporosis were examined to explore the relationship between intermittent bisphosphonate therapy, changes in bone resorption and fracture risk. The magnitude of the reduction of the rate of bone resorption at the end of the drug-free interval rather than its fluctuation pattern after bisphosphonate administration determines antifracture efficacy, provided that these fluctuations occur within the premenopausal range. Prolongation of the drug-free interval beyond 2 weeks should be compensated by a dose higher than the cumulative daily dose.

Intermittent Bisphosphonate Therapy in Postmenopausal Osteoporosis

Bisphosphonates are the most widely prescribed drugs in osteoporosis today. They have unequivocally shown their ability to reduce fracture rate at the spine (alendronic acid, risedronic acid, ibandronic acid) and at the hip (alendronic acid and risedronic acid). However, their dosage and administration procedures and the adverse reactions induced by their oral intake are responsible for low adherence. Therefore, intermittent regimens have been developed. Weekly alendronic acid and risedronic acid provide similar benefits, in terms of bone mineral density (BMD) and changes in biochemical markers, as those seen with their daily formulations. Ibandronic acid has been shown to reduce vertebral fractures when given intermittently. Ibandronic acid given orally monthly and intravenously every 2 or 3 months provides increases in BMD similar to the daily formulation. Yearly intravenous infusions of zoledronic acid are currently being evaluated for their ability to reduce fractures. If the efficacy and safety of bisphosphonates given at administration intervals longer than weekly are confirmed, this might significantly improve patient adherence and long-term outcomes of bisphosphonate treatment in postmenopausal osteoporosis.

Density and structural changes in the bone of growing rats after weekly alendronate administration with and without a methotrexate challenge

Alendronate (ALN) and other bisphosphonates have been used successfully in pediatric patients with osteopenia secondary to connective tissue diseases. Loss of growth in height has not been reported, but concerns remain regarding the effect of these potent antiresorptive agents when used in children and adolescents. High-dose methotrexate (MTX) and other chemotherapy drugs have been implicated in osteoporosis and a high fracture incidence in survivors of childhood cancers and are also associated with osteopenia in adult animals. The effect of high dose MTX on bone density during rapid skeletal growth, however, has not been widely studied, nor has the potentially therapeutic effect of bisphosphonates in this setting. We examined the effects of ALN and MTX administration, alone and in combination, on bone density, morphology, mechanical strength, and longitudinal growth in normal growing rats. Sprague-Dawley rats were given ALN once weekly (0.3 mg/kg) from 5 to 11 weeks of age, with and without a course of methotrexate (MTX) given daily in weeks 1 and 3 (0.75 mg/kg/day). Twenty-four animals were randomly divided into four groups: Control (vehicle), ALN alone, ALN + MTX, and MTX alone. After 6 weeks, the femora, tibiae, and lumbar spine were studied by dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, mechanical strength testing, microradiography, light microscopy, and by determination of ash weights and bone lengths. ALN treatment increased bone mineral density (BMD) by 23% to 68%. The largest increases in the femur occurred in the distal third where endochondral bone growth was greatest and included large increases in trabecular bone and total cross-sectional area. ALN + MTX produced similar effects to ALN alone. MTX only reduced BMD by 8% in the vertebrae, but not significantly at other sites. MTX also led to femoral length reductions of 2.9%. The small reductions in BMD due to MTX were overwhelmed by the increases due to ALN, whereas the length loss was unaffected. Transverse density banding corresponding to weekly ALN administrations were clearly evident radiographically throughout the growing skeleton, likely due to decreased resorption and possibly increased mineralization in the bands. ALN or ALN + MTX treatment also led to increases in mechanical strength in the femora. Although MTX administration during growth leads to some BMD reduction, ALN given with MTX eliminates this reduction and in fact bone density and strength increase above control levels.

Prevention and treatment of postmenopausal osteoporosis

Osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration of the skeleton leading to enhanced bone fragility and an increased risk of fracture. Prior to fracture, diagnosis is established by documenting low bone mass. In the first section of this article we review the clinical use of bone mass measurements and biochemical markers of bone remodeling in selecting patients most in need of preventive therapy at menopause. Women with high bone turnover lose bone at menopause more rapidly than those with normal bone turnover and are more likely to derive benefit from the several preventive therapies available. The second section addresses the available technologies used to diagnose osteoporosis and/or establish fragility fracture risk using noninvasive bone mass measurement and biochemical markers of bone remodeling separately or in combination. In the third section we review the several treatment options available for patients with osteoporosis, including alendronate (alendronic acid), risendronate (risedronic acid), calcitonin, teriparatide, and raloxifene, and the approaches to monitoring the therapeutic response. The final section deals with fall protection--an often forgotten aspect of management of the patient at risk for sustaining and osteoporotic fragility fracture.

Bone loss and the evolving role of bisphosphonate therapy in prostate cancer

Androgen deprivation therapy (ADT) can result in significant loss of bone mineral density (BMD) but to date, there are no prospective studies that document the true severity of bone loss and resulting fracture rates. In the general population, however, the incidence of low BMD is increasing in elderly men. Men suffer more morbidity and mortality from fractures associated with low BMD than women. Problems of underdiagnosis and undertreatment in men can be addressed with enhanced awareness of the risk factors for bone loss in men and the available treatment options. Guidelines for diagnosis of low BMD in women can probably be applied to men. Treatment options have not been studied as extensively in men. For men treated with ADT for prostate cancer, however, use of intravenous zoledronic acid at the initiation of ADT has been shown to prevent and even reverse bone loss. Although the routine use of bisphosphonates to prevent bone loss is not yet recommended, zoledronic acid is a logical choice of therapy in men who have low BMD at baseline or who develop bone loss during the course of therapy. In addition to its effects on BMD, zoledronic acid has also been shown to decrease skeletal morbidity in men with metastatic hormone-refractory prostate cancer. Whether zoledronic acid or other bisphosphonates might actually prevent or delay the development of bone metastases remains to be studied in randomized clinical trials.

Understanding treatments for bone loss and bone metastases in patients with prostate cancer: a practical review and guide for the clinician

Prostate cancer patients are at risk for developing bone loss and bone metastases. Clinicians prescribing ADT should appreciate the potential effects of ADT on BMD as well as the morbidity and mortality that can result from osteoporotic fractures. Measures to address the evaluation of patients and when to treat patients with significant bone loss have been discussed. Bisphosphonates effectively prevent loss of BMD in prostate cancer patients. Treatment of prostate cancer patients with established bone metastases with zoledronic acid should be considered strongly based on the results of the Saad study and other studies of patients with bone metastases with other malignancies. Zoledronic acid is approved by the US FDA for use in men with metastatic hormone-refractory prostate cancer and in the European Union for any patient with bone metastases, including prostate cancer patients,because of the beneficial impact of zoledronic acid on skeletal-related events. There is no validated method to determine which patients might benefit most from bisphosphonate therapy in this setting. Many questions about the use of bisphosphonate therapy in men with prostate cancer must be addressed, both in terms of the use in bone loss and bone metastases. These questions include: What is the optimal timing of therapy? Which bisphosphonate is best? What is the best dose and dose schedule? Do bisphosphonates effectively decrease skeletal fracture rates in patients with osteoporosis? How long should patients receive therapy? Are bisphosphonate "holidays" warranted? What are the long-term skeletal and renal toxicities? Is there a role for sequencing bisphosphonate therapy either before or after chemotherapy? Is bisphosphonate therapy synergistic with certain chemotherapy or other bone-targeted therapies? Which patients are the most likely to benefit from bisphosphonate therapy? What are clinically significant endpoints of bisphosphonate trials in patients with metastatic disease? Does inhibiting bone turnover also inhibit formation of bone metastases? Preliminary work in these areas has been completed, but more questions than answers are available. Given the rising costs of health care, it is imperative that these questions be addressed to best use the health care dollar while offering high-risk patients the best available therapy. At present, no data suggest that bisphosphonates should be used routinely to prevent BMD loss in men with normal BMD or to prevent the development of bone metastases in men with biochemical relapse. Continuing trials may give us guidance in the future.

Cellular mechanism of inhibition of osteoclastic resorption of bone and calcified cartilage by long-term pamidronate administration in ovariectomized mature rats

We examined the effects of long-term bisphosphonate (BP, pamidronate) administration at a therapeutic dose (1.5 mg/kg/day) on the distribution, structure, and vacuolar-type H(+)-ATPase expression of osteoclasts, and the resulting trabecular bone volume and structure in ovariectomized (OVX) mature rats. Six-month-old female rats were allocated to sham-operated control, untreated-OVX, and BP-administered OVX groups. Postoperatively, BP was administered intraperitoneally once a day to OVX rats for up to 30 days. On postoperative days 14, 30, and 60, all of the rats were killed and the distal metaphyseal area of the dissected humeri was examined. Quantitative backscattered-electron image analysis revealed that the trabecular bone volume/unit medullary area in untreated OVX rats was significantly (P < 0.05) lower than that in sham-operated controls at 30 and 60 days postoperation. BP administration significantly (P < 0.05) increased trabecular bone volume at 14, 30, and 60 days postoperation in BP-administered OVX rats compared to both sham-operated and untreated OVX rats. Compared to untreated OVX rats, the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts along the bone trabeculae in BP-administered OVX rats was not significantly decreased on days 14 and 30, but was significantly decreased on day 60. Ultrastructurally, BP administration caused the disappearance of both the ruffled border (RB) and the clear zone (CZ) structures, and decreased the expression of vacuolar-type H(+)-ATPase in most osteoclasts, but did not significantly induce apoptosis of osteoclasts detected by the terminal dUTP nick end-labeling (TUNEL) method. Our results suggest that long-term BP administration significantly reduces bone and calcified cartilage resorption through impairment of the structure and bone-resorbing function of osteoclasts, and thereby effectively maintains trabecular bone volume and structure in ovariectomy-induced acute estrogen deficiency in mature rats.

Oral weekly ibandronate prevents bone loss in postmenopausal women

OBJECTIVES

To investigate the efficacy, safety, and dose-response of once-weekly oral ibandronate in the prevention of postmenopausal bone loss.

DESIGN

This was a multi-centre, placebo-controlled, double-blind, randomized, 24-month phase II/III dose-finding study.

SETTING

Primary care units in 14 osteoporosis centres.

SUBJECTS

A total of 630 women were stratified into four strata according to time since menopause (TSM, 1-3 vs. >3 years) and baseline bone mineral density (BMD; normal: T-score > or =1 vs. osteopenic: -2.5 < or = T-score < or = 1) of the lumbar spine.

INTERVENTIONS

Within each stratum women were further randomized to receive once-weekly ibandronate (5, 10, or 20 mg week-1) or placebo for 24 months.

MAIN OUTCOME MEASURES

Efficacy parameters were the relative changes from baseline in spine (L1-4) and hip BMD, and biochemical markers of bone turnover (serum and urinary C-telopeptide of collagen type I (CTx), osteocalcin, and alkaline phosphatase) measured by dual energy X-ray absorptiometry and enzyme immunoassays, respectively.

RESULTS

Once-weekly therapy with ibandronate induced dose-dependent increases in spine and hip BMD. At month 24, differences between the relative changes in spine and hip BMD induced by 20 mg ibandronate and placebo was 4.0 and 2.7%, respectively. Similar or more pronounced differences were seen in osteopenic women of TSM 1-3 years (5.3 and 3.5%) and of TSM >3 years (3.5 and 2.9%), respectively. A dose-dependent suppression of all biochemical markers of bone turnover was observed with significant decreases in the 20 mg dose groups of all strata at month 24. The overall safety results indicated that once-weekly oral ibandronate was well-tolerated at all three doses.

CONCLUSION

Once-weekly oral therapy with 20 mg ibandronate provides an effective and safe therapy for the prevention of postmenopausal bone loss.

Oral ibandronate: changes in markers of bone turnover during adequately dosed continuous and weekly therapy and during different suboptimally dosed treatment regimens

The aims of the present study were to investigate how changes in the cumulative dose and the frequency of dosing influence the short-term antiresorptive efficacy of oral ibandronate treatment and whether serial measurements of bone markers could provide a useful diagnostic tool for the revelation of noncompliance to established treatments with antiresorptive drugs. Study participants were 200 healthy women 50-70 years old (mean 63.1 years) with a lumbar spine BMD t-score of -1 to -5. Women were randomly allocated to receive treatment with oral ibandronate according to one of the following eight dosing regimes: (1) 2.5 mg daily for 84 days; (2) 20 mg weekly for 84 days; (3) 2.5 mg daily for 28 days + no treatment for 56 days; (4) 2.5 mg daily for 28 days + 2.5 mg weekly for 56 days; (5) 2.5 mg daily for 28 days + 2.5 mg three times weekly for 56 days; (6) 2.5 mg daily for 14 days + 2.5 mg three times weekly for 56 days; (7) 2.5 mg three times weekly for 84 days; (8) no treatment for 168 days. Study parameters were the serum concentration of the C-terminal telopeptide of collagen type I (s-CTX, resorption marker) and N-MID osteocalcin (formation marker) measured by enzyme-linked immunosorbent assay. Oral treatment with ibandronate 20 mg weekly (cumulative dose 240 mg) resulted in greater final inhibition in s-CTX and area under the curve (AUC) compared to the 2.5 mg daily treatment (cumulative dose 210 mg), indicating that as long as optimal doses are administered the frequency of dosing has secondary importance for overall efficacy. When the cumulative dose was 130 mg or less, the final degree of inhibition was still the function of the cumulative dose, but the overall efficacy estimated by the AUC was also under the influence of the frequency of dosing. These observations suggest that serial measurements of s-CTX may provide a useful diagnostic tool for the early revelation of suboptimal dosing or noncompliance to already optimized therapies with antiresorptive agents.

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

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

Zoledronate once-yearly increases bone mineral density--implications for osteoporosis

Osteoporosis is a major and growing problem for older women and men in western society. The bisphosphonates are used to treat postmenopausal osteoporosis because they decrease the risk of fractures. Oral bisphosphonates may cause oesophageal irritation and injury and are poorly absorbed. Intermittent intravenous bisphosphonates, including zoledronate, may be a way to avoid the problems associated with oral administration. Intravenous zoledronate increased bone mineral density while decreasing bone turnover and formation. Interestingly, the effects of a single dose (4 mg) of zoledronate were maintained over a year and were similar to those of three-monthly dosing with 0.25 - 1 mg zoledronate. If the increases in bone mineral density with zoledronate translate into reduced fractures, once-yearly intravenous zoledronate could be simple prophylaxis for postmenopausal osteoporosis.

Increase of bone alkaline phosphatase after androgen deprivation therapy in patients with prostate cancer

OBJECTIVES

To evaluate the behavior of bone alkaline phosphatase (BAP) after androgen deprivation therapy in patients with prostate cancer.

METHODS

BAP was determined in the serum of 35 patients with nonmetastatic prostate cancer before maximal androgen blockade. During 5 years of follow-up, BAP was determined annually. A subset of 36 patients who underwent radical prostatectomy as the only treatment for prostate cancer was selected as a control group.

RESULTS

The mean pretreatment BAP serum concentration was similar in both groups (10.8 and 10.4 ng/mL, P >0.05). However, after 5 years, the mean BAP serum concentration increased 64.8% in the study group (from 10.8 to 17.6 ng/mL, P < 0.001); it remained stable in the control group (from 10.4 to 10.4 ng/mL). The increase of serum BAP in patients receiving androgen deprivation was 32.4% during the first year (from 10.8 to 14.3 ng/ml), 16.7% during the second (from 14.3 to 16.1 ng/mL), 7.4% during the third (from 16.1 to 16.9 ng/mL), 5.5% during the fourth (from 16.9 to 17.3 ng/mL), and 2.8% during the fifth year (from 17.3 to 17.6 ng/mL).

CONCLUSIONS

Androgen deprivation produces an increase in the BAP serum concentration. A major increase seems to be produced during the first year of follow-up and thereafter this increase is reduced around 50% annually.

Intermittent dosing of alendronate

OBJECTIVE

To review data describing use of intermittent dosing of alendronate.

DATA SOURCES

A comprehensive literature search was conducted using MEDLINE (1966-May 2001) and EMBASE (1974-May 2001) databases to identify all information regarding intermittent dosing of alendronate.

DATA SYNTHESIS

A small number of clinical studies have evaluated the use of intermittent alendronate dosing in an attempt to improve patient compliance and adverse events.

CONCLUSIONS

Evidence from more controlled clinical trials and postmarketing data are needed to demonstrate the therapeutic efficacy and tolerability of intermittent alendronate dosing. The definitive role of intermittent dosing in patients with postmenopausal osteoporosis remains to be determined.

Ibandronate: a comparison of oral daily dosing versus intermittent dosing in postmenopausal osteoporosis

The objective of this study was to compare efficacy and safety of continuous versus intermittent oral dosing of ibandronate. Two hundred forty women aged 55-75 years with postmenopausal osteoporosis were randomized to active treatment or placebo. Similar total doses of ibandronate were provided by treatment regimens with either continuous 2.5 mg of ibandronate daily (n = 81) or intermittent 20 mg of ibandronate every other day for the first 24 days, followed by 9 weeks without active drug (n = 78). The placebo group (total, n = 81) was crossed over after 12 months to receive either continuous (n = 37) or intermittent ibandronate (n = 35). By 24 months, bone mineral density (BMD) had increased significantly relative to baseline in both active treatment groups. The continuous and intermittent groups showed statistically equivalent increases in lumbar spine BMD of +5.64% (+/-0.53) and +5.54% (+/-0.53) and in total hip of +3.35% (+/-0.40) and +3.41% (+/-0.40), respectively (per protocol population). Biochemical markers of bone turnover decreased significantly in both treatment groups. The level of marker suppression was similar, although the intermittent group displayed, as expected, more fluctuation over the treatment period. The frequency of adverse events was similar in the treatment groups. In conclusion, the intermittent and continuous regimens showed equivalent changes in BMD and bone turnover. These results confirm previous preclinical findings indicating that the efficacy of ibandronate depends on the total oral dose given rather than on the dosing schedule. This supports development of new flexible dosing regimens targeted to minimize the frequency of dosing, which are expected to improve convenience and lead to enhanced long-term patient compliance.

Bisphosphonates in renal osteodystrophy

The present review considers the role that bisphosphonates might have in patients with renal failure. Although bisphosphonates are widely used to reduce fracture risk in patients with osteoporosis, few studies have documented their effect in patients with renal osteodystrophy. The pathogenesis of bone loss after renal transplantation and the role of the recently identified osteoprotegerin/receptor activating nuclear factor-kappaB system is described. Inhibition of bone resorption may prove beneficial when high bone turnover is present, but there are potential drawbacks to widespread use of bisphosphonates. These issues are discussed, with emphasis placed on reports published within the past 18 months.

Design and conduct of clinical trials in hormone replacement therapy

Postmenopausal hormone replacement therapy represents an area of outstanding importance in preventive medicine that greatly affects personal well-being as well as public health. The number of women living in the United States who are 50 years or older has been estimated at nearly 50 million. Many of those women are likely to be eligible for postmenopausal hormone replacement, which may consist either of estrogen replacement therapy (ERT) in women without a uterus or, more frequently, estrogen/progestin combination therapy (HRT) in women with a uterus. This chapter first presents an overview of general regulatory requirements pertaining to the design and conduct of clinical studies in support of marketing approval for a drug product. These requirements include, but are not restricted to, studies in HRT. The chapter next discusses the design and conduct of clinical trials in support of marketing approval for the indications: treatment of moderate to severe vasomotor symptoms and vulvovaginal atrophy; prevention of osteoporosis; and protection by adjunctive progestin against estrogen-induced endometrial hyperplasia/cancer in women with a uterus. Finally, data related to the potential cardioprotective action of HRT and its protection against Alzheimer's disease and colon cancer are discussed.

Nonoperative management of hyperparathyroidism: present and future

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