Effect of 1 year of discontinuation of raloxifene or estrogen therapy on bone mineral density after 5 years of treatment in healthy postmenopausal women

How long should patients take medications for postmenopausal osteoporosis?

Several medications have proved effective in reducing the fracture risk in postmenopausal women with osteoporosis. The optimal duration of use of these medications remains to be established, however. Gains in bone mineral density (BMD) persisted throughout 10 years of treatment with alendronate or 7 years with risedronate. However, proof of long-term protection against fractures was obtained only for shorter treatment periods, 4 years with alendronate and 5 years with risedronate. The persistence of treatment effects after drug discontinuation varies across medications, and further studies are needed before this point can be incorporated into treatment decisions. With raloxifene, the BMD effect observed after 3 and 4 years persisted when the drug was given for 8 years, and the fracture risk reduction was similar after 4 years and after 3 years. The long-term safety profile also was similar, with a significant decrease in the incidence of invasive estrogen-receptor-positive breast cancer and a persistent increase in the risk of deep vein thrombosis. However, a sharp drop in BMD occurred upon raloxifene discontinuation. Thus, 4 years may be appropriate for anti-resorptive drug therapy. However, the optimal treatment duration should be determined on a case-by-case basis according to the results of regular fracture-risk evaluations.

Skeletal consequences of hormone therapy discontinuance: a systematic review

Although hormone therapy protects against bone loss after menopause, currently it is not recommended once menopausal symptoms have subsided. We reviewed randomized clinical trials to quantify bone loss after stopping hormone therapy and summarize treatment options for women who discontinue hormone treatment. We conducted a search of MEDLINE and EMBASE for randomized, controlled trials measuring bone mineral density (BMD) after hormone therapy discontinuation. Other known published and unpublished data were also included. Eleven studies fulfilled the search criteria. In each, bone loss was rapid after stopping hormone therapy, with BMD declines ranging from 2.3% to 6.2% in the first year. Increases in bone turnover markers also occurred rapidly when hormone therapy was stopped. Limited data addressing treatment after hormone therapy is stopped exist; only 2 studies specifically evaluated therapy to protect bone after hormone discontinuation. Taken together, these 2 studies demonstrate that alendronate produced significant increases relative to placebo in spine, hip, and total body BMD in women with low bone density who had discontinued hormone therapy within the past 3 months, preventing the rapid bone loss seen on discontinuation of hormone therapy. Among treatment options for preventing bone loss on discontinuation of hormone therapy for which randomized clinical trial data are available, alendronate prevented bone loss or increased bone density in postmenopausal women with low bone density. Women who are discontinuing hormone therapy should be counseled about potential bone loss and effective treatment options.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to state that discontinuation of replacement menopausal hormone therapy, which protects against bone loss, is not recommended after menopause symptoms have subsided; recall that it may accelerate bone loss; and explain that there is bone loss preventive treatment for women after discontinuation of hormone therapy.

Management of osteoporosis in postmenopausal women

OBJECTIVE

To update the evidence-based position statement published by The North American Menopause Society (NAMS) in 2002 regarding the management of osteoporosis in postmenopausal women.

DESIGN

NAMS followed the general principles established for evidence-based guidelines to create this updated document. A panel of clinicians and researchers expert in the field of metabolic bone diseases and/or women's health were enlisted to review the 2002 NAMS position statement, compile supporting statements, and reach consensus on recommendations. The panel's recommendations were reviewed and approved by the NAMS Board of Trustees.

RESULTS

Osteoporosis, whose prevalence is especially high among elderly postmenopausal women, increases the risk of fractures. Hip and spine fractures are associated with particularly high morbidity and mortality in this population. Given the health implications of osteoporotic fractures, the primary goal of osteoporosis therapy is to prevent fractures, which is accomplished by slowing or stopping bone loss, maintaining bone strength, and minimizing or eliminating factors that may contribute to fractures. The evaluation of postmenopausal women for osteoporosis risk requires a medical history, physical examination, and diagnostic tests. Major risk factors for postmenopausal osteoporosis (as defined by bone mineral density) include advanced age, genetics, lifestyle factors (such as low calcium and vitamin D intake, smoking), thinness, and menopause status. The most common risk factors for osteoporotic fracture are advanced age, low bone mineral density, and previous fracture as an adult. Management focuses first on nonpharmacologic measures, such as a balanced diet, adequate calcium and vitamin D intake, adequate exercise, smoking cessation, avoidance of excessive alcohol intake, and fall prevention. If pharmacologic therapy is indicated, government-approved options are bisphosphonates, a selective estrogen-receptor modulator, parathyroid hormone, estrogens, and calcitonin.

CONCLUSIONS

Management strategies for postmenopausal women involve identifying those at risk of low bone density and fracture, followed by instituting measures that focus on reducing modifiable risk factors through lifestyle changes and, if indicated, pharmacologic therapy.

Efficacy and safety of alendronate and risedronate for postmenopausal osteoporosis

INTRODUCTION

This paper discusses the efficacy and safety of alendronate and risedronate in the treatment of postmenopausal osteoporosis.

METHODS

The literature was searched with the PubMed from 1996 to the present, with respect to strictly conducted systematic reviews with homogeneity, meta-analyses with homogeneity, and randomized controlled trials (RCTs) with narrow Confidence Interval.

RESULTS

According to the results of large randomized controlled trials (RCTs), bisphosphonates (alendronate, risedronate, and ibandronate), raloxifene, calcitonin, parathyroid hormone (PTH), and strontium ranelate effectively prevent vertebral fractures in postmenopausal women with osteoporosis. Because raloxifene has been shown to be effective in preventing the initial vertebral fracture in postmenopausal osteoporotic women without prevalent vertebral fractures, it is considered in the treatment of postmenopausal women with mild osteoporosis or osteopenia with some risk factors for fractures. RCTs have also demonstrated that alendronate, risedronate, PTH, and strontium are useful to prevent non-vertebral fractures and that alendronate and risedronate prevent hip fractures, thus alendronate or risedronate are primarily considered as the first-line drugs in the treatment of elderly women with osteoporosis having some risk factors for falls. While it has been suggested that PTH may be considered in patients with severe osteoporosis, the use of PTH in the treatment for osteoporosis is limited to 2 years or less, and it may be appropriate to use other anti-resorptive drugs after the completion of PTH treatment to maintain the skeletal effects gained during the treatment. RCTs have demonstrated that the incidence of gastrointestinal tract adverse events in postmenopausal osteoporotic women treated with bisphosphonates and placebo are similar, and also the long-term efficacy and safety of alendronate and risedronate.

CONCLUSION

The evidence derived from the literature, based on strict evidence-based medicine guidelines, suggests that there is long-term efficacy and safety with alendronate and risedronate in the treatment of osteoporosis in postmenopausal women.

Who will benefit from treatment with selective estrogen receptor modulators (SERMs)?

Clinical trials have demonstrated that the selective estrogen receptor modulator raloxifene can reduce the risk of vertebral fracture, but have not unequivocally demonstrated an effect on non-vertebral fracture. Consequently it is recommended that raloxifene be used mainly in postmenopausal women with milder osteoporosis as a preventive measure or for treatment in those with predominantly spinal osteoporosis. Since the effects of raloxifene on bone mineral density and bone turnover may reverse soon after cessation, it is recommended that raloxifene be used as long-term therapy for 5-10 years. Because of its quicker offset, use of raloxifene may have advantages over potent bisphosphonates if use of anabolic agents are contemplated in an individual patient.

Strategies for the prevention and treatment of osteoporosis during early postmenopause

During the perimenopause, both the quantity and quality of bone decline rapidly, resulting in a dramatic increase in the risk of fracture in postmenopausal women. Although many factors are known to be associated with osteoporotic fractures, measures to identify and treat women at risk are underused in clinical practice. Consequently, osteoporosis is frequently not detected until a fracture occurs. Identification of postmenopausal women at high risk of fracture therefore is a priority and is especially important for women in early postmenopause who can benefit from early intervention to maintain or to increase bone mass and, thus, reduce the risk of fracture. Most authorities recommend risk-factor assessment for all postmenopausal women, followed by bone mineral density measurements for women at highest risk (ie, all women aged > or =65 years, postmenopausal women aged <65 years with > or =1 additional risk factors for osteoporosis, and postmenopausal women with fragility fractures). All postmenopausal women can benefit from nonpharmacologic interventions to reduce the risk of fracture, including a balanced diet with adequate intake of calcium and vitamin D, regular exercise, measures to prevent falls or to minimize their impact, smoking cessation, and moderation of alcohol intake. Several pharmacologic agents, including the bisphosphonates (eg, alendronate, risedronate, and ibandronate) and the selective estrogen receptor modulator, raloxifene, have been shown to increase bone mass, to reduce fracture risk, and to have acceptable side-effect profiles. Women who have discontinued hormone therapy are in particular need of monitoring for fracture risk, in light of the accelerated bone loss and increased risk of fracture that occurs after withdrawal of estrogen treatment.

Skeletal effects of raloxifene after 8 years: results from the continuing outcomes relevant to Evista (CORE) study

In the CORE breast cancer trial of 4011 women continuing from MORE, the incidence of nonvertebral fractures at 8 years was similar between placebo and raloxifene 60 mg/day. CORE had limitations for assessing fracture risk. In a subset of 386 women, 7 years of raloxifene treatment significantly increased lumbar spine and femoral neck BMD compared from the baseline of MORE.

INTRODUCTION

The multicenter, double-blind Continuing Outcomes Relevant to Evista (CORE) trial assessed the effects of raloxifene on breast cancer for 4 additional years beyond the 4-year Multiple Outcomes of Raloxifene Evaluation (MORE) osteoporosis treatment trial.

MATERIALS AND METHODS

In CORE, placebo-treated women from MORE continued with placebo (n = 1286), whereas those previously given raloxifene (60 or 120 mg/day) received raloxifene 60 mg/day (n = 2725). As a secondary endpoint, new nonvertebral fractures were analyzed as time-to-first event in 4011 postmenopausal women at 8 years. A substudy assessed lumbar spine and femoral neck BMD at 7 years, with the primary analysis based on 386 women (127 placebo, 259 raloxifene) who did not take other bone-active agents from the fourth year of MORE and who were > or =80% compliant with study medication in CORE.

RESULTS

The risk of at least one new nonvertebral fracture was similar in the placebo (22.9%) and raloxifene (22.8%) groups (hazard ratio [HR], 1.00; Bonferroni-adjusted CI, 0.82, 1.21). The incidence of at least one new nonvertebral fracture at six major sites (clavicle, humerus, wrist, pelvis, hip, lower leg) was 17.5% in both groups. Posthoc Poisson analyses, which account for multiple events, showed no overall effect on nonvertebral fracture risk, and a decreased risk at six major nonvertebral sites in women with prevalent vertebral fractures (HR, 0.78; 95% CI, 0.63, 0.96). At 7 years after MORE randomization, the differences in mean lumbar spine and femoral neck BMD with raloxifene were 1.7% (p = 0.30) and 2.4% (p = 0.045), respectively, from placebo. Compared with MORE baseline, after 7 years, raloxifene treatment significantly increased lumbar spine (4.3% from baseline, 2.2% from placebo) and femoral neck BMD (1.9% from baseline, 3.0% from placebo). BMDs were significantly increased from MORE baseline at all time-points at both sites with raloxifene.

CONCLUSION

Raloxifene therapy had no effect on nonvertebral fracture risk after 8 years, although CORE had limitations for fracture risk assessment. BMD increases were maintained after 7 years of raloxifene.

Benefits and risks of sex hormone replacement in postmenopausal women

Because cardiovascular disease (CVD), which is far less common in young women than in men, but increases in prevalence in the postmenopausal years to that of men, estrogen repletion therapy (ERT) or combined hormone replacement therapy (HRT), has been widely used to protect against development of both CVD and osteoporosis, and possibly to delay or prevent cognitive loss or Alzheimer's disease (AD). To test the validity of favorable findings in many small-scale studies, and in clinical practice, a large-scale trial: the Women's Health Initiative (WHI) was undertaken by the National Institutes of Health (NIH), a trial that was prematurely ended because of increased CVD complications, despite some lessening of hip fractures. This paper suggests that the customary high intake of calcium (Ca)-advised to protect against osteoporosis, and the marginal magnesium (Mg) intake in the USA, might well be contributory to the adverse CV effects, that were all thromboembolic in nature. The procoagulant effect of estrogen is intensified by Ca; Mg-which counteracts many steps in the coagulation cascade and inhibits platelet aggregation and adhesion-is commonly consumed in sub-optimal amounts. The high American dietary Ca/Mg ratio might also be contributory to the WHI failure to confirm ERT's favorable mental effects. Discussed are mechanisms by which Mg enhances estrogen's central nervous system protective effects. Mg's improvement of cerebral blood flow, which improves brain metabolism, can also enhance removal of the beta amyloid peptide, accumulation of which is implicated in AD.

Changes in bone mineral density during and after 3 years' use of tamoxifen or toremifene

OBJECTIVES

To study the effects of tamoxifen and toremifene on bone mineral density (BMD) in postmenopausal women with breast cancer.

METHODS

Seventy patients with stage II-III breast cancer were randomized to start either tamoxifen (n = 36; 20 mg per day) or toremifene (n = 34; 40 mg per day) for 3 years. BMD in the lumbar spine and in the proximal femur was measured by dual-energy X-ray absorptiometry both before and during the treatment and 1 year after the discontinuation of the anti-estrogens.

RESULTS

The baseline BMD measurements were comparable between the groups. In 3 years, lumbar BMD decreased by 1.7% in tamoxifen (P = 0.048) and 3.0% in toremifene (P = 0.001) users (ns between the groups), and femoral neck BMD by 0.9% (P = 0.040) and 1.3% (P = ns), respectively. The use of hormone replacement therapy (HRT) until the diagnosis of breast cancer was associated with decreases in lumbar BMD during anti-estrogen regimen (4% at 3 years) in contrast to unchanged lumbar BMD in women with no previous use of HRT. During the 1st year after the cessation of anti-estrogen, lumbar BMD did not change at all in either group whereas femoral BMD decreased in both the groups at the rate of 1.5-3.2%, as expected.

CONCLUSIONS

We conclude that tamoxifen (20 mg) and toremifene (40 mg) have similar bone-sparing efficacy that in lumbar spine extends up to 1 year after the cessation of these regimens. This effect is not seen in lumbar spine BMD in those postmenopausal women who discontinue HRT at the time of breast cancer diagnosis.

Cost-effectiveness of raloxifene in the UK: an economic evaluation based on the MORE study

Raloxifene treatment has been shown to reduce the risk of vertebral fractures and breast cancer in postmenopausal women. The long-term economic implications of treatment with raloxifene have not yet been investigated. The aim of this study was to assess the cost-effectiveness of treating postmenopausal women in the UK with raloxifene. A previously developed computer simulation model was used to estimate the cost-effectiveness of osteoporotic treatments with extra skeletal benefits. The model was populated with epidemiological data and cost data relevant for a UK female population. Data on the effect of treatment were taken from the Multiple Outcomes of Raloxifene (MORE) study, which recruited women with low bone mineral density or with a prior vertebral fracture. Cost-effectiveness was estimated using Quality Adjusted Life Years (QALYs) and life years gained as primary outcome measures. The cost per QALY gained of treating postmenopausal women without prior vertebral fractures was 18,000 pounds, 23,000 pounds , 18,000 pounds and 21,000 pounds at 50, 60, 70 and 80 years of age. Corresponding estimates for women with prior vertebral fractures were 10,000 pounds, 24,000 pounds, 18,000 pounds and 20,000 pounds. In relation to threshold values that are recommended in the UK, the analysis suggests that raloxifene is cost-effective in the treatment of postmenopausal women at an increased risk of vertebral fractures.

Should postmenopausal hormone therapy be used to prevent osteoporosis?

OBJECTIVE

To discuss the risks and benefits of hormone therapy for the prevention of postmenopausal osteoporosis.

DATA SOURCES

A MEDLINE search was conducted to identify articles that are pertinent to the risks and benefits of hormone therapy for the prevention of postmenopausal osteoporosis. Additional references were obtained from the bibliographies of these articles.

STUDY SELECTION

Human studies that present efficacy and safety data for the effects of postmenopausal hormone therapy.

DATA EXTRACTION

Analysis of studies to determine the benefits of hormone therapy on bone (in terms of bone mineral density or fracture risk) and risks of hormone therapy in postmenopausal women.

DATA SYNTHESIS

Studies were analyzed to determine the risk-benefit profile of hormone therapy for the prevention of postmenopausal osteoporosis. This information was synthesized to help practitioners make decisions regarding the role of postmenopausal hormone therapy in the prevention of osteoporosis.

CONCLUSION

Given the risks of hormone therapy, some of which are associated with increased duration of use, hormone therapy cannot be routinely recommended for the sole purpose of preventing osteoporosis. Many alternative therapies exist that may offer patients a better benefit versus risk ratio.

Randomized trial of effect of alendronate continuation versus discontinuation in women with low BMD: results from the Fracture Intervention Trial long-term extension

To determine the effects of continuation versus discontinuation of alendronate on BMD and markers of bone turnover, we conducted an extension trial in which 1099 older women who received alendronate in the FIT were re-randomized to alendronate or placebo. Compared with women who stopped alendronate, those continuing alendronate for 3 years maintained a higher BMD and greater reduction of bone turnover, showing benefit of continued treatment. However, among women who discontinued alendronate and took placebo in the extension, BMD remained higher, and reduction in bone turnover was greater than values at FIT baseline, showing persistence of alendronate's effects on bone.

INTRODUCTION

Prior trials including the Fracture Intervention Trial (FIT) have found that therapy with alendronate increases BMD and decreases fracture risk for up to 4 years in postmenopausal women with low BMD. However, it is uncertain whether further therapy with alendronate results in preservation or further gains in BMD and if skeletal effects of alendronate continue after treatment is stopped.

MATERIALS AND METHODS

We conducted a follow-up placebo-controlled extension trial to FIT (FIT long-term extension [FLEX]) in which 1099 women 60-86 years of age who were assigned to alendronate in FIT with an average duration of use of 5 years were re-randomized for an additional 5 years to alendronate or placebo. The results of a preplanned interim analysis at 3 years are reported herein. Participants were re-randomized to alendronate 10 mg/day (30%), alendronate 5 mg/day (30%), or placebo (40%). All participants were encouraged to take a calcium (500 mg/day) and vitamin D (250 IU/day) supplement. The primary outcome was change in total hip BMD. Secondary endpoints included change in lumbar spine BMD and change in markers of bone turnover (bone-specific alkaline phosphatase and urinary type I collagen cross-linked N-telopeptide).

RESULTS

Among the women who had prior alendronate therapy in FIT, further therapy with alendronate (5 and 10 mg groups combined) for 3 years compared with placebo maintained BMD at the hip (2.0% difference; 95% CI, 1.6-2.5%) and further increased BMD at the spine (2.5% difference; 95% CI, 1.9-3. 1%). Markers of bone turnover increased among women discontinuing alendronate, whereas they remained stable in women continuing alendronate. Cumulative increases in BMD at the hip and spine and reductions in bone turnover from 8.6 years earlier at FIT baseline were greater for women continuing alendronate compared with those discontinuing alendronate. However, among women discontinuing alendronate and taking placebo in the extension, BMD remained higher and reduction in bone turnover was greater than values at FIT baseline.

CONCLUSIONS

Compared with women who stopped alendronate after an average of 5 years, those continuing alendronate maintained a higher BMD and greater reduction of bone turnover, showing benefit of continued alendronate treatment on BMD and bone turnover. On discontinuation of alendronate therapy, rates of change in BMD at the hip and spine resumed at the background rate, but discontinuation did not result in either accelerated bone loss or a marked increase in bone turnover, showing persistence of alendronate's effects on bone. Data on the effect of continuation versus discontinuation on fracture risk are needed before making definitive recommendations regarding the optimal length of alendronate treatment.

Ten years' experience with alendronate for osteoporosis in postmenopausal women

BACKGROUND

Antiresorptive agents are widely used to treat osteoporosis. We report the results of a multinational randomized, double-blind study, in which postmenopausal women with osteoporosis were treated with alendronate for up to 10 years.

METHODS

The initial three-year phase of the study compared three daily doses of alendronate with placebo. Women in the original placebo group received alendronate in years 4 and 5 and then were discharged. Women in the original active-treatment groups continued to receive alendronate during the initial extension (years 4 and 5). In two further extensions (years 6 and 7, and 8 through 10), women who had received 5 mg or 10 mg of alendronate daily continued on the same treatment. Women in the discontinuation group received 20 mg of alendronate daily for two years and 5 mg daily in years 3, 4, and 5, followed by five years of placebo. Randomized group assignments and blinding were maintained throughout the 10 years. We report results for the 247 women who participated in all four phases of the study.

RESULTS

Treatment with 10 mg of alendronate daily for 10 years produced mean increases in bone mineral density of 13.7 percent at the lumbar spine (95 percent confidence interval, 12.0 to 15.5 percent), 10.3 percent at the trochanter (95 percent confidence interval, 8.1 to 12.4 percent), 5.4 percent at the femoral neck (95 percent confidence interval, 3.5 to 7.4 percent), and 6.7 percent at the total proximal femur (95 percent confidence interval, 4.4 to 9.1 percent) as compared with base-line values; smaller gains occurred in the group given 5 mg daily. The discontinuation of alendronate resulted in a gradual loss of effect, as measured by bone density and biochemical markers of bone remodeling. Safety data, including fractures and stature, did not suggest that prolonged treatment resulted in any loss of benefit.

CONCLUSIONS

The therapeutic effects of alendronate were sustained, and the drug was well tolerated over a 10-year period. The discontinuation of alendronate resulted in the gradual loss of its effects.

Cost effectiveness of raloxifene in the treatment of osteoporosis in Sweden: an economic evaluation based on the MORE study

BACKGROUND

The Multiple Outcomes of Raloxifene Evaluation (MORE) study showed that treatment with raloxifene reduces the risk of vertebral fracture and breast cancer in postmenopausal women with osteoporosis.

OBJECTIVE

Based on the MORE study the aim of the present study was to assess the cost effectiveness of raloxifene (compared with no treatment) for the treatment of osteoporosis in postmenopausal women in Sweden.

DESIGN

A revised version of a previously developed computer simulation model was used. The impact of the risk-reducing effect of raloxifene on vertebral fractures and breast cancer on cost effectiveness was analysed using a clinical and a morphometric definition of vertebral fracture. Benefits of raloxifene treatment were measured in quality-adjusted life-years (QALYs) and life-years gained. The study estimated the cost effectiveness mainly from a healthcare perspective but the cost effectiveness taking a societal perspective was also analysed.

RESULTS

Intervention costs (in Swedish kronor [SEK] and euros [euro], year 2001 values) in postmenopausal women with a relative risk of vertebral fracture of 2 were SEK372000 (euro40000), SEK303000 (euro33000) and SEK263000 (euro28000) per QALY for women aged 60, 70 and 80 years, at start of treatment, respectively, when the clinical vertebral definition was used. The cost effectiveness using a clinical morphometric vertebral fracture definition was similar to the cost effectiveness using a clinical vertebral fracture definition.

CONCLUSIONS

In relation to accepted threshold values for cost per QALY in Sweden, this model indicates, with its underlying assumptions and data, that raloxifene (compared with no treatment) is cost effective for the treatment of postmenopausal women at an increased risk of vertebral fracture, from the Swedish healthcare and societal perspectives.

Skeletal and nonskeletal effects of raloxifene

Raloxifene, a selective estrogen receptor modulator, is approved for the prevention and treatment of postmenopausal osteoporosis. Prevention studies with raloxifene have demonstrated preservation of bone density and suppression of bone turnover markers in young postmenopausal women. The Multiple Outcomes of Raloxifene Evaluation study was the pivotal treatment trial for raloxifene. It demonstrated significant reduction in the risk for vertebral fractures after 1 and 3 years. Significant reduction of nonvertebral fractures with raloxifene has not yet been demonstrated. In addition to the effects of raloxifene on bone, potentially beneficial effects on the cardiovascular system, breast, and uterus have been described. Most of these nonskeletal effects have been reported as secondary endpoints from large osteoporosis trials with raloxifene. Prospective, randomized, double-blind studies of raloxifene with breast cancer prevention and cardiovascular protection as primary endpoints are now underway.

Preventive effects of sequential treatment with alendronate and 1 alpha-hydroxyvitamin D3 on bone mass and strength in ovariectomized rats

Because accumulating evidence has shown that bisphosphonates are unable to maintain their bone-sparing effects after the withdrawal of the drug, a replacement treatment is needed when bisphosphonate treatment cannot be continued for some reason. The present study investigated the preventive effects of alendronate followed by 1alpha(OH)D3 on the mass and mechanical strength of trabecular and cortical bones in ovariectomized rats. Sprague-Dawley rats were ovariectomized or sham-operated at 48 weeks of age. Ovariectomized rats treated with vehicle alone (OVX group) showed significant decreases in bone mineral density (BMD) and mechanical strength of the lumbar vertebra and the midfemur during a 20-week period after the operation as compared with sham-operated rats. These decreases were prevented by continuous treatment with alendronate (0.5 mg/kg/day, po) for 20 weeks (ALN-C group), whereas the values reverted to those of the OVX group when alendronate was withdrawn at 10 weeks (ALN-W group). The sequential treatment with alendronate and 1alpha(OH)D3 (0.05 microg/kg/day, po) for 10 weeks each (ALN --> 1alpha group) resulted in higher BMD and mechanical strength of the lumbar vertebra and the midfemur in this group than in the OVX and ALN-W groups. The increase in mechanical strength was proportional to that in BMD at both sites, suggesting that the stimulatory effects of these treatments on bone strength were due to those on bone mass. Analyses of histology, computed tomography, and biochemical markers confirmed the preventive effects of the sequential treatment. Therefore, we propose that 1alpha(OH)D3 may be a good choice to replace alendronate when alendronate treatment cannot be continued for some reason.

Selective estrogen-receptor modulators

Tamoxifen is useful for adjuvant treatment of breast cancer and in some women for the prevention of breast cancer. The risk-benefit ratio in regard to the skeleton and perhaps other organ systems may very well be different for postmenopausal versus premenopausal women. In postmenopausal women, tamoxifen (20 mg/d) increased BMD in the spine and perhaps the hip; however, the effect on fracture risk is unclear. Therefore, for postmenopausal women with osteoporosis, consideration should be given to the addition of an agent that is shown to have efficacy against fractures (such as bisphosphonates), even while these women are on tamoxifen. For women at only modest or moderate risk, with bone density above the osteoporosis range (T score above -2.5) and no major fracture history, tamoxifen is probably adequate for 5 years of use. Potentially serious adverse effects include venous thromboembolism, uterine cancer, benign uterine disease, and cataracts. Raloxifene (60 mg/d) protects against vertebral fractures over 4 years in women with osteoporosis, produces small increases in bone mass of the spine, hip, and total body, and reduces bone turnover in postmenopausal women with or without osteoporosis. No significant effect has yet been demonstrated on nonvertebral fractures after 4 years of treatment. Raloxifene has the additional benefit of substantially reducing the risk of ER-positive invasive breast cancer and does not increase the risk of uterine disease. Raloxifene increases the risk of venous thromboembolic disease to the same degree as tamoxifen and estrogen. Therefore, SERMS and estrogens are generally contraindicated in women with a previous history of venous thromboembolism or those who are at significantly increased risk. Raloxifene is probably most useful in women who have osteoporosis (T score = -2.5) or who are at risk (T score less than -1.5 with clinical risk factors) in the middle menopausal period (age 55-65) or in the early menopausal period in women who have no significant hot flashes. At this stage in life, vertebral fractures are common, but hip fractures are not. Therefore, women who take raloxifene can expect a reduction in the likelihood of having a vertebral fracture, and possibly breast cancer. The lack of definitive efficacy against hip fracture is not a major deterrent to use of this agent in this age group because hip fracture risk is very low. Raloxifene might not be the treatment of choice for elderly women who are at particularly high risk of hip fracture.