Short-term effect of alendronate on bone mass and bone remodeling in postmenopausal women

Supplement With Calcium or Alendronate Suppresses Osteopenia Due to Long Term Rabeprazole Treatment in Female Mice: Influence on Bone TRAP and Osteopontin Levels

Background and Purpose

Rabeprazole, a proton pump inhibitor (PPIs) is much endorsed to patients with increased gastric acidity. PPIs were accused to have osteoporotic effects on patients who chronically use them. The point of the current investigation was to decide the impact of rabeprazole on osteoporosis and to explore the modulatory effects of dietary calcium or alendronate on this side effect.

Methods

80 female mice were alienated into four groups maintained for 18 weeks: [1] Vehicle group: given distilled water in 12 ml/kg, P.O. [2] Rabeprazole control group: given rabeprazole in a dose equals 10 mg/kg every 48 h, P.O. [3] Rabeprazole + calcium: given rabeprazole (10 mg/kg every 48 h) along with calcium supplement. [4] Rabeprazole + alendronate: given rabeprazole (10 mg/kg every 48 h) and alendronate (1 mg/kg per week, i.p.). Serum calcium, phosphorus and parathyroid hormone were measured. Both femurs were kept in paraformaldehyde, and then the right one was used for X-ray examination with analysis by Digora software and the left one for histopathological examination (H&E) and immunohistochemical stains for osteopontin and tartrate resistant acid phosphatase (TRAP).

Results

Calcium supplementation or administration of alendronate along with rabeprazole significantly restored the mean bone density as shown by X-ray analysis. Femurs from mice received rabeprazole showed widely separated, thin-walled bone trabeculae and increased number of osteoclasts. Calcium or alendronate with rabeprazole showed thick bone trabeculae without full recovery from rabeprazole induced damage. Adding calcium supplementation to rabeprazole did not affect the histological abnormalities related to osteoclasts meanwhile alendronate produced inactivation of osteoclasts. Both calcium and alendronate decreased the rabeprazole-induced increment in the femur osteopontin level.

Conclusion

Calcium or alendronate can be recommended for female patients on PPI therapy who are at risk of osteopenia.

Calcium Homeostasis: A Potential Vicious Cycle of Bone Metastasis in Breast Cancers

Cancers have been considered as one of the most severe health problems in the world. Efforts to elucidate the cancer progression reveal the importance of bone metastasis for tumor malignancy, one of the leading causes for high mortality rate. Multiple cancers develop bone metastasis, from which breast cancers exhibit the highest rate and have been well-recognized. Numerous cells and environmental factors have been believed to synergistically facilitate bone metastasis in breast cancers, from which breast cancer cells, osteoclasts, osteoblasts, and their produced cytokines have been well-recognized to form a vicious cycle that aggravates tumor malignancy. Except the cytokines or chemokines, calcium ions are another element largely released from bones during bone metastasis that leads to hypercalcemia, however, have not been well-characterized yet in modulation of bone metastasis. Calcium ions act as a type of unique second messenger that exhibits omnipotent functions in numerous cells, including tumor cells, osteoclasts, and osteoblasts. Calcium ions cannot be produced in the cells and are dynamically fluxed among extracellular calcium pools, intracellular calcium storages and cytosolic calcium signals, namely calcium homeostasis, raising a possibility that calcium ions released from bone during bone metastasis would further enhance bone metastasis and aggravate tumor progression via the vicious cycle due to abnormal calcium homeostasis in breast cancer cells, osteoclasts and osteoblasts. TRPs, VGCCs, SOCE, and P2Xs are four major calcium channels/routes mediating extracellular calcium entry and affect calcium homeostasis. Here we will summarize the overall functions of these four calcium channels in breast cancer cells, osteoclasts and osteoblasts, providing evidence of calcium homeostasis as a vicious cycle in modulation of bone metastasis in breast cancers.

Metabolite Profiling Reveals the Effect of Dietary Rubus coreanus Vinegar on Ovariectomy-Induced Osteoporosis in a Rat Model

The study was aimed at exploring the curative effects of Rubus coreanus (RC) vinegar against postmenopausal osteoporosis by using ovariectomized rats as a model. The investigations were performed in five groups: sham, ovariectomized (OVX) rats without treatment, low-dose RC vinegar (LRV)-treated OVX rats, high-dose RC vinegar (HRV)-treated OVX rats and alendronate (ALEN)-treated OVX rats. The efficacy of RC vinegar was evaluated using physical, biochemical, histological and metabolomic parameters. Compared to the OVX rats, the LRV and HRV groups showed positive effects on the aforementioned parameters, indicating estrogen regulation. Plasma metabolome analysis of the groups using gas chromatography-time of flight mass spectrometry (GC-TOF-MS) and ultra-performance liquid chromatography quadrupole-TOF-MS (UPLC-Q-TOF-MS) with multivariate analysis revealed 19 and 16 metabolites, respectively. Notably, the levels of butyric acid, phenylalanine, glucose, tryptophan and some lysophosphatidylcholines were marginally increased in RC vinegar-treated groups compared to OVX. However, the pattern of metabolite levels in RC vinegar-treated groups was found similar to ALEN, but differed significantly from that in sham group. The results highlight the prophylactic and curative potential of dietary vinegar against postmenopausal osteoporosis. RC vinegar could be an effective natural alternative for the prevention of postmenopausal osteoporosis.

Symptomatic Hypocalcemia Associated with Zoledronic Acid Treatment for Osteoporosis: A Case Report

Intravenous bisphosphonates are widely used in the management of solid tumors, metastatic bone disease, metabolic bone diseases and hypercalcemia of malignancies. Recently, yearly intravenous injections of zoledronic acid, one of the potent nitrogen-containing bisphosphonates, have also been approved for the prevention and treatment of osteoporosis. Although infrequently observed, asymptomatic hypocalcemia mainly due to intravenous bisphosphonates has been documented. Here we report a female patient who exhibited profound symptomatic hypocalcemia after receiving intravenous zoledronic acid as treatment of postmenopausal osteoporosis. The patient was not assessed for calcium status prior to the intravenous bisphosphonate therapy, and she was later found to have severe vitamin D deficiency. To our knowledge, this is the first patient with symptomatic hypocalcemia to be reported after zoledronic acid was approved for the management of osteoporosis. We highlight the importance of evaluating calcium and vitamin D levels before initiating intravenous bisphosphonate treatment, particularly in the presence of widespread vitamin D deficiency and the likelihood of future increases in the prescription of intravenous bisphosphonates.

Current recommendations for laboratory testing and use of bone turnover markers in management of osteoporosis

Osteoporosis is a major health problem worldwide, and is projected to increase exponentially due to the aging of the population. The absolute fracture risk in individual subjects is calculated by the use of algorithms which include bone mineral density (BMD), age, gender, history of prior fracture and other risk factors. This review describes the laboratory investigations into osteoporosis which include serum calcium, phosphate, creatinine, alkaline phosphatase and 25-hydroxyvitamin D and, additionally in men, testosterone. Parathyroid hormone (PTH) is measured in patients with abnormal serum calcium to determine its cause. Other laboratory investigations such as thyroid function testing, screening for multiple myeloma, and screening for Cushing's syndrome, are performed if indicated. Measurement of bone turnover markers (BTMs) is currently not included in algorithms for fracture risk calculations due to the lack of data. However, BTMs may be useful for monitoring osteoporosis treatment. Further studies of the reference BTMs serum carboxy terminal telopeptide of collagen type I (s-CTX) and serum procollagen type I N-terminal propeptide (s-PINP) in fracture risk prediction and in monitoring various treatments for osteoporosis may help expedite their inclusion in routine clinical practice.

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.

Safety and tolerability of zoledronic acid and other bisphosphonates in osteoporosis management

Bisphosphonates (BPs) are widely used in the treatment of postmenopausal osteoporosis and other metabolic bone diseases. They bind strongly to bone matrix and reduce bone loss through inhibition of osteoclast activity. They are classified as nitrogen- and non-nitrogen-containing bisphosphonates (NBPs and NNBPs, respectively). The former inhibit farnesyl diphosphate synthase while the latter induce the production of toxic analogs of adenosine triphosphate. These mechanisms of action are associated with different antifracture efficacy, and NBPs show the most powerful action. Moreover, recent evidence indicates that NBPs can also stimulate osteoblast activity and differentiation. Several randomized control trials have demonstrated that NBPs significantly improve bone mineral density, suppress bone turnover, and reduce the incidence of both vertebral and nonvertebral fragility fractures. Although they are generally considered safe, some side effects are reported (esophagitis, acute phase reaction, hypocalcemia, uveitis), and compliance with therapy is often inadequate. In particular, gastrointestinal discomfort is frequent with the older daily oral administrations and is responsible for a high proportion of discontinuation. The most recent weekly and monthly formulations, and in particular the yearly infusion of zoledronate, significantly improve persistence with treatment, and optimize clinical, densitometric, and antifracture outcomes.

Short-term oral magnesium supplementation suppresses bone turnover in postmenopausal osteoporotic women

Magnesium has been shown to increase bone mineral density when used in the treatment of osteoporosis, yet its mechanism of action is obscure. In this study, the effects of daily oral magnesium supplementation on biochemical markers of bone turnover were investigated. Twenty postmenopausal women have been divided into two groups. Ten patients were given magnesium citrate (1,830 mg/day) orally for 30 days. Ten postmenopausal women of matching age, menopause duration, and BMI were recruited as the control group and followed without any medication. Fasting blood and first-void urine samples were collected on days 0, 1, 5, 10, 20, and 30, respectively. Total magnesium, calcium, phosphorus, iPTH and osteocalcin were determined in blood samples. Deoxypyridinoline levels adjusted for creatinine were measured in urine samples. Thirty consecutive days of oral magnesium supplementation caused significantly decrease in serum iPTH levels in the Mg-supplemented group (p < 0.05). Serum osteocalcin levels were significantly increased (p < 0.001) and urinary deoxypyridinoline levels were decreased (p < 0.001) in the Mg-supplemented group. This study has demonstrated that oral magnesium supplementation in postmenopausal osteoporotic women suppresses bone turnover.

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).

Cathepsin K inhibitors prevent matrix-derived growth factor degradation by human osteoclasts

The coupling between bone formation and resorption creates a therapeutic impasse in osteoporosis: antiresorptive therapy halts bone loss, but also inhibits bone formation, and therefore does not cure the condition. Surprisingly, recent preliminary reports suggest that inhibition of resorption by cathepsin K (CathK) inhibitors augments bone formation. Uniquely amongst resorption-inhibitors, CathK-inhibitors suppress degradation of the organic matrix of bone while allowing demineralization. We hypothesized that these unique characteristics might explain a capacity of CathK inhibitors to enhance bone formation: the inhibitors might prevent degradation not only of collagen, but also other proteins, including growth factors embedded in matrix. We tested this hypothesis using osteocalcin and insulin-like growth factor I (IGF-I) as examples of matrix-embedded proteins, and found that CathK-inhibitors, unlike other resorption-inhibitors, dramatically increased the concentrations of these matrix-derived proteins in supernatants of osteoclasts on bone, most likely through protection against intracellular degradation. We found that protons are both necessary and sufficient for the release of IGF-I from bone matrix, and that recombinant CathK can degrade both marker proteins. In the presence of a CathK-inhibitor, the amount of IGF-I released from matrix substantially exceeded the amount secreted by osteoclasts. CathK-inhibition similarly augmented bone morphogenetic protein (BMP)-2 release. Lastly, MC3T3-E1 numbers were greater after co-culture with osteoclasts on bone with versus without CathK-inhibitor, showing that, in the presence of CathK-inhibitor, osteoclasts release biologically-significant quantities of biologically-active matrix-derived growth factors. These results support a model in which osteoclastic secretion of protons demineralizes bone, causing release of growth factors from bone matrix. Normally these are largely degraded, with collagen, in the resorptive hemivacuole and during transcytosis to the basal surface of the osteoclast, but in the presence of CathK inhibitor they are released intact, and so might augment bone formation.

Meta-analyses of therapies for postmenopausal osteoporosis. II. Meta-analysis of alendronate for the treatment of postmenopausal women

OBJECTIVE

To review the effect of alendronate on bone density and fractures in postmenopausal women.

DATA SOURCE

We searched MEDLINE, EMBASE, Current Contents, and the Cochrane Controlled trials registry from 1980 to 1999, and we examined citations of relevant articles and proceedings of international meetings.

STUDY SELECTION

We included 11 trials that randomized women to alendronate or placebo and measured bone density for at least 1 yr.

DATA EXTRACTION

For each trial, three independent reviewers assessed the methodological quality and abstracted data.

DATA SYNTHESIS

The pooled relative risk (RR) for vertebral fractures in patients given 5 mg or more of alendronate was 0.52 [95% confidence interval (CI), 0.43-0.65]. The RR of nonvertebral fractures in patients given 10 mg or more of alendronate was 0.51 (95% CI 0.38-0.69), an appreciably greater effect than for the 5 mg dose. We found a similar reduction in RR across nonvertebral fracture types; in particular, RR reductions for fractures traditionally thought to be "osteoporotic," such as hip and forearm, were very similar to RR reductions for "nonosteoporotic" fractures. Individual studies showed similar results, reflected in the P values of the test of heterogeneity (P = 0.99 for vertebral and 0.88 for nonvertebral fractures). Alendronate produced positive effects on the percentage change in bone density, which increased with both dose and time. After 3 yr of treatment with 10 mg of alendronate or more, the pooled estimate of the difference in percentage change between alendronate and placebo was 7.48% (95% CI 6.12-8.85) for the lumbar spine (2-3 yr), 5.60% (95% CI 4.80-6.39) for the hip (3-4 yr), 2.08% (95% CI 1.53-2.63) for the forearm (2-4 yr), and 2.73% (95% CI 2.27-3.20) for the total body (3 yr). Heterogeneity of the treatment effect of alendronate was not consistently explained by any of our a priori hypotheses; in particular, the effect was very similar in prevention and treatment studies. The pooled RR for discontinuing medication due to adverse effects for 5 mg or greater of alendronate was 1.15 (95% CI 0.93-1.42). The pooled RR for discontinuing medication due to gastro-intestinal (GI) side effects for 5 mg or greater was 1.03 (0.81-1.30, P = 0.83), and the pooled RR for GI adverse effects with continuation of medication was 1.03 (0.98 to 1.07) P = 0.23.

CONCLUSIONS

Alendronate increases bone density in both early postmenopausal women and those with established osteoporosis while reducing the rate of vertebral fracture over 2-3 yr of treatment. Reductions in nonvertebral fractures are evident among postmenopausal women without prevalent fractures and have bone mineral density (BMD) levels below the World Health Organization threshold for osteoporosis. The impact on fractures appears consistent across all fracture types, casting doubt on traditional distinctions between osteoporotic and nonosteoporotic fractures.

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

In clinical practice, a large proportion of patients have bone mass values for which a therapeutic intervention is considered necessary, but the accepted aim might be the sole preservation or marginal increases of the actual bone mass. These goals might be achieved with lower or intermittent doses of a powerful agent for the purpose of fewer side effects and improved compliance. The aim of this study was to assess the effects of two intermittent alendronate regimens in the treatment of postmenopausal osteoporosis. One hundred twenty-four postmenopausal women (age range 52-75 years, at least 7 years since last menopause) with a bone mineral density (BMD) at either the femoral neck or lumbar spine of 2 SD below the mean values of young healthy individuals, and without a history of previous osteoporotic fracture, were randomly assigned either to calcium/vitamin D supplements, alone or associated with two different intermittent oral alendronate regimens: 20 mg once a week (weekly alendronate group) or 10 mg daily (orally) for 1 month out of 3 (cyclical alendronate group). After 1 year, in both groups given intermittent alendronate, we observed significant increases in BMD at both the spine (+2.2 +/- 2.6 and +2.5 +/- 2.9) and femoral neck (+1.6 +/- 4.8 and +1.5 +/- 2.2) for the weekly and cyclical regimens, respectively. This was associated with a significant diminution of both serum bone-specific alkaline phosphatase and urinary N-telopeptides of collagen type I excretion. In the patients in the control group BMD decreased significantly at the lumbar spine, with a slight decline of serum bone-specific alkaline phosphatase. Compliance with treatment and drug tolerability were good in both alendronate groups. In conclusion, intermittent alendronate administration at cumulative doses (and costs) three times lower than those currently recommended for osteoporosis treatment is very well accepted, and is able to significantly increase BMD at the spine and femoral neck and to decrease the markers of bone turnover. These regimens can be clinically useful in the long-term treatment of postmenopausal osteoporosis without prevalent osteoporotic fractures, particularly in women with lower compliance for continuous administration.

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

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

Effect of three years of oral alendronate treatment in postmenopausal women with osteoporosis

OBJECTIVE

Oral alendronate sodium is a potent, specific inhibitor of osteoclast-mediated bone resorption. To assess its efficacy and safety, a 3-year, randomized, double-blind, multicenter study of 478 postmenopausal women with osteoporosis was conducted.

PATIENTS AND METHODS

Subjects received either placebo, alendronate 5 or 10 mg/day for 3 years, or 20 mg/day for 2 years followed by 5 mg/day for 1 year (20/5 mg). All subjects received 500 mg/day of supplemental calcium. Bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DXA).

RESULTS

After 3 years, alendronate 10 mg induced marked increases in BMD of the lumbar spine (9.6 +/- 0.4%), femoral neck (4.7 +/- 0.7%) and trochanter (7.4 +/- 0.6%) (mean +/- SE; each P < or = 0.001) versus decreases of 0.8 to 1.6% with placebo. Progressive increases at these sites in the alendoronate 10 mg group were significant during both the second and third years. Alendronate 10 mg increased total body BMD (1.6 +/- 0.3%, P < or = 0.001), and prevented loss but did not increase BMD at the 1/3 forearm site. Alendronate 20/5 mg was no more effective, whereas alendronate 5 mg was significantly less effective than 10 mg at all sites. Bone turnover decreased to a stable nadir over 3 months for resorption markers (urine deoxypyridinoline) and over 6 months for formation markers (alkaline phosphatase and osteocalcin). Mean loss of stature was reduced by 41% in alendronate treated subjects (P = 0.01).

CONCLUSION

The safety profile of alendronate was similar to that of placebo. At 10 mg, there were no trends toward increased frequency of any adverse experience except for abdominal pain, which was usually mild, transient, and resolved with continued treatment. Thus, alendronate appears to be an important advance in the treatment of osteoporosis in postmenopausal women.

Cyclical clodronate is effective in preventing postmenopausal bone loss: a comparative study with transcutaneous hormone replacement therapy

An investigative study was carried out for 2 years involving 124 randomly selected early postmenopausal women with spine bone mineral density (BMD) below the mean value of a normal premenopausal subject. After random division into three groups, the first 42 patients were treated with transcutaneous 17-beta-estradiol (50 micrograms daily), the second 42 were treated with cyclical intravenous clodronate (200 mg/month iv infusion), and the third group of 40 (controls) was left untreated. After 2 years, the total drop in BMD within the control group was more than 7% as opposed to the values of -0.14% +/- 0.93 in the estradiol group and 0.67% +/- 0.84 in the clodronate group. A change in BMD of < 1% was considered satisfactory, and this result was obtained in 32% of the controls, in 79% of the estradiol group where the percentage change in BMD moderately correlated with serum estradiol levels (r = 0.399), and in 90% of the clodronate-treated patients, in whom the percentage change in BMD inversely correlated with basal values of markers of bone turnover. Both estrogen and clodronate prevent postmenopausal bone loss. The response to transcutaneous hormone replacement therapy may be influenced by transcutaneous absorption and by a lower sensitivity to estrogen. Response to cyclical clodronate seems to be influenced by the rate of bone turnover. An interdosage interval ranging from 2-4 weeks appears suitable for most patients.

Efficacy of treatment of osteoporotic fractures

The efficacy of osteoporosis therapy can be considered at several different levels, ranging from the overall community to the individual patient. Efficacy has different connotations for each group within the community and for the individual, in whom life expectancy--among other parameters--is an important consideration. Some of the questions addressed in this article are the scope of the osteoporosis problem, how many people must be treated for prevention of one further fracture, whether there is a role for targeting likely high risk/high response groups, and what exactly is a successful outcome. Clearly, there are no ideal therapies as yet for osteoporosis, in the context of either prevention or treatment. Moreover, most studies have been performed in selected groups within the community, and the extrapolation to wider clinical subsets is not straightforward. For example, data are almost nonexistent for men or premenopausal women; also it is not clear whether studies on carefully selected healthy elderly women can be simply extrapolated to their less healthy cohorts. Similarly, studies using vertebral deformities as the primary endpoint may be difficult to relate to symptomatic vertebral fractures, and other peripheral fractures including proximal femur. Lastly, the efficacy of some treatments must be related to the risk of further fractures. Thus, many years of therapy may relate to prevention of perhaps only one symptomatic event, with equivocal cost-benefit for the individual. As new therapies are under development, these questions need to be addressed for the efficacy of osteoporosis therapy to be considered.