Intermittent treatment with intravenous 4-amino-1-hydroxybutylidene-1,1-bisphosphonate (AHBuBP) in the therapy of postmenopausal osteoporosis

Physiology of the aging bone and mechanisms of action of bisphosphonates

Fragility fractures, a major public health concern, are expected to further increase due to aging of the world populations because age remains a cardinal, independent determinant of fracture risk. With aging the balance between bone formation and resorption during the remodeling process becomes negative, with increased resorption and reduced formation. Bisphosphonates (BPs) are widely prescribed anti-resorptive agents that inhibit osteoclasts attachment to bone matrix and enhance osteoclast apoptosis. BPs can be divided into nitrogen-containing (N-BPs) and non-nitrogen-containing BPs (non-N-BPs). Both classes induce apoptosis but they evoke it differently. Several studies have examined the molecular mechanisms underlying BPs' effects on osteoclasts and bone remodeling. N-BPs (alendronate, risedronate, zoledronate) inhibit the intracellular mevalonate pathway and protein isoprenylation, via the enzyme farnesyl pyrophosphate synthase. N-BPs act by competition, binding to the natural substrate-binding site of the enzyme. The less potent non-N-BPs (etidronate, clodronate), do not inhibit the mevalonate pathway and protein isoprenylation, but are metabolized intracellularly to metabolites, which are cytotoxic analogs of ATP. N-BPs represent the first choice treatment for diseases associated with excessive bone resorption, such as fragility fractures (due to postmenopausal-, male, glucocorticoid- and transplant-induced osteoporosis), Paget's disease of bone, and bone metastasis. Better understanding of BPs' effects on osteoblasts/osteocytes (e.g., preventing apoptosis) and differential distribution may further help explain anti-fracture benefit and bone quality effects. Lower affinity BPs (e.g., risedronate) may allow better access to osteocyte network. Effects of BPs on bone senescence, cancer cells apoptosis and prevention of cardiovascular calcifications may open new avenues for biogerontological research.

Otosclerosis 2: the medical management of otosclerosis

The rationale for medical therapy for otospongiosis is to slow down and eventually stop the phase of bone resorption. There is some increase in the incidence of stapedial otospongiosis in a low-fluoride area compared with a high-fluoride area. Sodium fluoride treatment has a role to play in preventing the onset and progression of hearing loss in patients suffering from otosclerosis. Sodium fluoride therapy has been shown to have some beneficial effect on dizziness associated with otosclerosis. In view of the possibility of systemic side effects of sodium fluoride therapy, a regular follow up of patients is warranted. Biphosphonates can be used as an alternative treatment to sodium fluoride in cases where the patient is intolerant to sodium fluoride therapy. Hearing aid is also a treatment option, but it does not halt the disease process.

Systematic review: impaired drug absorption related to the co-administration of antisecretory therapy

BACKGROUND

Due to suppression of gastric acidity during antisecretory therapy, an impaired absorption of co-administered drugs may occur.

AIM

To review evidence of impaired drug absorption related to the use of co-administered PPIs or H2RAs.

METHODS

Systematic search of MEDLINE/EMBASE/SCOPUS databases (1980-September 2008) for English articles with keywords: drug malabsorption and absorption, stomach, anti-secretory/acid inhibitory drugs, histamine H2 antagonists, PPIs, gastric acid, pH, hypochlorhydria, gastric hypoacidity. From 2126 retrieved articles, 16 randomized crossover studies were identified investigating impaired absorption of nine different drugs in association with co-administration of PPIs or H2RAs. Information on investigated drug, study type, features of investigated subjects, study design, type of intervention, and study results were extracted.

RESULTS

The identified studies investigated the absorption kinetics of nine drugs. Acid suppression reduced absorption of ketoconazole, itraconazole, atazanavir, cefpodoxime, enoxacin and dipyridamole (median C(max) reduction by 66.5%). An increased absorption of nifedipine and digoxin (median AUC increase by 10%) and a 2-fold-increase in alendronate bioavailability were observed.

CONCLUSIONS

Gastric pH appears relevant for absorption of some cardiovascular or infectious disease agents. Antisecretory treatment may significantly modify the absorption of co-administered drugs.

Efficacy of intravenous alendronate for the treatment of glucocorticoid-induced osteoporosis in children with autoimmune diseases

Our objective was to investigate the efficacy of intravenous alendronate for the treatment of glucocorticoid-induced osteoporosis (GIOP) in children with autoimmune diseases. Five children with autoimmune disease and GIOP were treated with 5 mg intravenous alendronate once every 3 months. After 1 and 2 years, we evaluated the changes in the Z score of the femoral neck bone mineral density (BMD), serum bone alkaline phosphatase, and urinary deoxypyridinoline. Six patients with GIOP, whose BMD could be observed over a 1-year period without alendronate treatment, were defined as controls. After 1 and 2 years of treatment, intravenous treatment significantly inhibited bone loss. The efficacy of alendronate demonstrated a significant correlation with a high level of bone turnover markers before alendronate treatment. Intravenous alendronate is considered to be a good choice for the treatment of GIOP because of its excellent efficacy. In addition, our study suggests that the efficacy of alendronate depends on the bone turnover of patients before treatment. Intervention with bisphosphonates during periods of high bone turnover may be recommended.

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.

Effects of neridronate treatment in elderly women with osteoporosis

Osteoporosis is a common disorder, especially among elderly post-menopausal women. Elderly women are often affected by co-morbidities, impaired gastrointestinal function and reduced mobility; therefore, the treatment strategy for their osteoporosis can be difficult. In this randomized pilot study, we have investigated the effects of a 12-month treatment with neridronate on bone mineral density (BMD), bone turnover markers and quality of life (QoL). The study included 40 women (age, 65-80 yr; post-menopausal period, >15yr) from a single osteoporosis centre. Twenty women received a monthly im injection of 25 mg of neridronate associated with a daily dose of 500 mg of calcium and 400 U of vitamin D. Twenty women received calcium plus vitamin D supplements alone. Changes in BMD at the lumbar spine and femoral neck were measured by dual energy X-ray absorptiometry. Serum type I collagen C-telopeptide (sCTX), urinary free-deoxypyridinoline (ufDPD), bone alkaline phosphatase (ALP) and serum osteocalcin levels were determined. For the QoL assessment, the Italian version of the SF-36 test was administrated. Spine and hip BMD rose by 6.6 +/- 3 and 4.2 +/- 2.3%, respectively (p < 0.05), after 12 months of neridronate treatment. Markers of skeletal turnover significantly fell already after 3 months of neridronate treatment and decreased progressively thereafter within 12 months. The mean decrease at 12 months ranged from 38 +/- 11% for sCTX to 25.2 +/- 15% for ufDPD (p < 0.001, all). The mean improvement in QoL in the treated group was 45.7% for bodily pain, 37.5% for general health perception, 23.1% for vitality, 18% for emotional role functioning and 12% for physical role functioning. The changes observed in BMD, turnover markers and QoL in the untreated group were ns. The intermittent neridronate administration was easily manageable and well tolerated. In conclusion, neridronate currently represents a valid option for the treatment of osteoporosis, since it helps just as much as oral BPs in the improvement of BMD and in particular conditions it can be even more effective.

Pamidronate increases bone mineral density in women with postmenopausal or steroid-induced osteoporosis

INTRODUCTION

We aimed to determine the efficacy and safety of a cyclic intravenous therapy with pamidronate in patients with postmenopausal or glucocorticoid-induced osteoporosis.

METHODS

We enrolled 86 Austrian female patients with postmenopausal (n = 69, mean age 68.13 +/- 1.14) or glucocorticoid-induced (n = 17, mean age 66.89 +/- 2.03) osteoporosis defined as a T-score of < -2.5 for bone mineral density (BMD) of the lumbar spine L1-L4. Patients received a single intravenous dose of 30 mg pamidronate at 3 months intervals. The per cent change in BMD was primary, whereas the safety and the biological response were secondary endpoints.

RESULTS

Seventy-six female patients (88%) completed study. Sixty patients received pamidronate therapy for the treatment of late postmenopausal osteoporosis and 16 patients received the same treatment for glucocorticoid-induced osteoporosis. At the end of the trial, lumbar spine (L1-L4) BMD increased significantly in patients with postmenopausal osteoporosis (P = 0.000067), whereas in patients with glucocorticoid-induced osteoporosis no significant change was observed (P = 0.724). The increase in the Ward's triangle BMD did not reach significance level in postmenopausal women receiving pamidronate (P = 0.0740). However, pamidronate treatment for glucocorticoid-induced osteoporosis resulted in a significant increase in Ward's triangle BMD (P = 0.0029). The efficacy of pamidronate treatment for postmenopausal osteoporosis was also reflected in a decrease in circulating biochemical markers for bone formation, including alkaline phosphatase and osteocalcin. In addition, pamidronate was well tolerated with no incidence of severe gastrointestinal events.

CONCLUSION

Cyclic intravenous administration of pamidronate is well-tolerated therapy in postmenopausal osteoporosis, and increases spinal BMD. Randomized controlled studies with adequate number of patients are needed to test the efficacy of the compound in the treatment of glucocorticoid-induced osteoporosis.

Effects of oral ibandronate administered daily or intermittently on fracture risk in postmenopausal osteoporosis

Oral daily (2.5 mg) and intermittent ibandronate (between-dose interval of >2 months), delivering a similar cumulative exposure, were evaluated in 2946 osteoporotic women with prevalent vertebral fracture. Significant reduction in incident vertebral fracture risk by 62% and 50%, respectively, was shown after 3 years. This is the first study to prospectively show antifracture efficacy for the intermittent administration of a bisphosphonate.

INTRODUCTION

Bisphosphonates are important therapeutics in postmenopausal osteoporosis. However, they are currently associated with stringent dosing instructions that may impair patient compliance and hence therapeutic efficacy. Less frequent, intermittent administration may help to overcome these deficiencies. This study assessed the efficacy and safety of oral ibandronate administered either daily or intermittently with a dose-free interval of >2 months.

MATERIALS AND METHODS

This randomized, double-blind, placebo-controlled, parallel-group study enrolled 2946 postmenopausal women with a BMD T score < or = -2.0 at the lumbar spine in at least one vertebra (L1-L4) and one to four prevalent vertebral fractures (T4-L4). Patients received placebo or oral ibandronate administered either daily (2.5 mg) or intermittently (20 mg every other day for 12 doses every 3 months).

RESULTS AND CONCLUSIONS

After 3 years, the rate of new vertebral fractures was significantly reduced in patients receiving oral daily (4.7%) and intermittent ibandronate (4.9%), relative to placebo (9.6%). Thus, daily and intermittent oral ibandronate significantly reduced the risk of new morphometric vertebral fractures by 62% (p = 0.0001) and 50% (p = 0.0006), respectively, versus placebo. Both treatment groups also produced a statistically significant relative risk reduction in clinical vertebral fractures (49% and 48% for daily and intermittent ibandronate, respectively). Significant and progressive increases in lumbar spine (6.5%, 5.7%, and 1.3% for daily ibandronate, intermittent ibandronate, and placebo, respectively, at 3 years) and hip BMD, normalization of bone turnover, and significantly less height loss than in the placebo group were also observed for both ibandronate regimens. The overall population was at low risk for osteoporotic fractures. Consequently, the incidence of nonvertebral fractures was similar between the ibandronate and placebo groups after 3 years (9.1%, 8.9%, and 8.2% in the daily, intermittent, and placebo groups, respectively; difference between arms not significant). However, findings from a posthoc analysis showed that the daily regimen reduces the risk of nonvertebral fractures (69%; p = 0.012) in a higher-risk subgroup (femoral neck BMD T score < -3.0). In addition, oral ibandronate was well tolerated. Oral ibandronate, whether administered daily or intermittently with an extended between-dose interval of >2 months, is highly effective in reducing the incidence of osteoporotic fractures in postmenopausal women. This is the first time that significant fracture efficacy has been prospectively shown with an intermittently administered bisphosphonate in the overall study population of a randomized, controlled clinical trial. Thus, oral ibandronate holds promise as an effective and convenient alternative to current bisphosphonate therapies.

Insufficiently dosed intravenous ibandronate injections are associated with suboptimal antifracture efficacy in postmenopausal osteoporosis

Less frequent bisphosphonate dosing in women with postmenopausal osteoporosis has the potential to promote therapy adherence through improved convenience. Ibandronate is a highly potent nitrogen-containing bisphosphonate, proven to significantly increase vertebral and nonvertebral bone mineral density (BMD) when administered as a convenient intravenous injection. A recent double-blind, placebo-controlled, randomized phase III study explored the antifracture efficacy and safety of 1 and 0.5 mg iv ibandronate injections, given once every 3 months, in 2862 women (55-76 years) with postmenopausal osteoporosis [one to four prevalent vertebral fractures and lumbar spine (L1-L4) BMD T score of less than -2.0 and greater than -5.0 in >or=1 vertebra]. All participants received daily vitamin D (400 IU) and calcium (500 mg) supplementation. The primary endpoint was the incidence of new morphometric vertebral fractures after 3 years. However, although a consistent trend toward a reduction in the incidence of new morphometric vertebral fracture was observed in the active treatment arms compared with placebo (9.2% vs. 8.7% vs. 10.7% in the 1 mg, 0.5 mg and placebo groups, respectively), as well as in the incidence of nonvertebral and hip fractures, the magnitude of fracture reduction was suboptimal and was insufficient to achieve statistical significance. At the studied doses, intravenous ibandronate injections also produced dose-dependent, but comparatively small, increases in lumbar spine BMD (4.0% and 2.9%, respectively) and decreases in biochemical markers of bone resorption and formation, relative to placebo. Optimal fracture efficacy likely requires more substantial increases in BMD and more pronounced suppression of bone turnover. In light of the clear dose-response relationship observed in this and other studies, this is likely to be achieved with higher intravenous doses of ibandronate. The results of a recent phase II/III study (Intermittent Regimen Intravenous Ibandronate Study: the IRIS study) provide support for this hypothesis.

Intravenous bisphosphonate therapy for osteoporosis: where do we stand?

The use of oral bisphosphonates, particularly members of the aminobisphosphonate subclass, is well established for the treatment of osteoporosis. In a number of clinical settings, intravenous administration appears to be advantageous. However, current dosing and efficacy data are limited while definitive, long-term trials with some of these agents are ongoing. In this article, we review the available information and discuss the use of these drugs on that basis.

Injectable bisphosphonates in the treatment of postmenopausal osteoporosis

Osteoporosis is a "silent" disease and the patient has usually no clue of it until the occurrence of a fragility fracture. Prevention requires a continuous daily treatment that could be uncomfortable to the patient. Besides the recently introduced weekly oral schedules, injectable bisphosphonates have often been used as an off-label option to ameliorate compliance. In general, although with different efficiency, almost all injectable bisphosphonates can improve bone mineral density and suppress bone resorption markers. The effect of intravenous infusions of bisphosphonates are, to a large extent, similar to equivalent intramuscular administrations, but doses and dosing intervals represent the critical issues. Pain at the injection site and acute phase reactions are relatively common to intramuscular clodronate and intravenous infusions of nitrogen-containing bisphosphonates, respectively. Under certain circumstances, intermittent treatment with injectable bisphosphonates might represent a feasible alternative when compliance is at risk.

Bisphosphonate treatment of osteoporosis

Bisphosphonates represent the agents of choice for most patients with osteoporosis. They are the best studied of all agents for the prevention of bone loss and reduction in fractures. They increase BMD, primarily at the lumbar spine, but also at the proximal femur. In patients who have established osteoporosis, bisphosphonates reduce the risk of vertebral fractures, and are the only agents in prospective trials to reduce the risk of hip fractures and other nonvertebral fractures. Bisphosphonates reduce the risk of fracture quickly. The risk of radiographic vertebral deformities is reduced after 1 year of treatment with risedronate [68]. The risk of clinical vertebral fractures is reduced after 1 year of treatment with alendronate [69] and just 6 months' treatment with risedronate [157]. The antifracture effect of risedronate has been shown to continue through 5 years of treatment [158]. Alendronate and risedronate are approved by the FDA for prevention of bone loss in recently menopausal women, for treatment of postmenopausal osteoporosis, and for prevention (risedronate) and treatment (alendronate and risedronate) of glucocorticoid-induced osteoporosis. Alendronate is also approved for treatment of osteoporosis in men. Other bisphosphonates (etidronate for oral use, pamidronate and zoledronate for intravenous infusion) are also available and can be used off label for patients who cannot tolerate approved agents. Although bisphosphonates combined with estrogen or raloxifene produce greater gains in bone mass compared with single-agent treatment, the use of two antiresorptive agents in combination cannot be recommended because the benefit on fracture risk has not been demonstrated and because of increased cost and side effects.

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.

Intravenous zoledronic acid in postmenopausal women with low bone mineral density

BACKGROUND

Bisphosphonates are effective agents for the management of osteoporosis. Their low bioavailability and low potency necessitate frequent administration on an empty stomach, which may reduce compliance. Gastrointestinal intolerance limits maximal dosing. Although intermittent intravenous treatments have been used, the optimal doses and dosing interval have not been systematically explored.

METHODS

We studied the effects of five regimens of zoledronic acid, the most potent bisphosphonate, on bone turnover and density in 351 postmenopausal women with low bone mineral density in a one-year, randomized, double-blind, placebo-controlled trial. Women received placebo or intravenous zoledronic acid in doses of 0.25 mg, 0.5 mg, or 1 mg at three-month intervals. In addition, one group received a total annual dose of 4 mg as a single dose, and another received two doses of 2 mg each, six months apart. Lumbar-spine bone mineral density was the primary end point.

RESULTS

There were similar increases in bone mineral density in all the zoledronic acid groups to values for the spine that were 4.3 to 5.1 percent higher than those in the placebo group (P<0.001) and values for the femoral neck that were 3.1 to 3.5 percent higher than those in the placebo group (P<0.001). Biochemical markers of bone resorption were significantly suppressed throughout the study in all zoledronic acid groups. Myalgia and pyrexia occurred more commonly in the zoledronic acid groups, but treatment-related dropout rates were similar to that in the placebo group.

CONCLUSIONS

Zoledronic acid infusions given at intervals of up to one year produce effects on bone turnover and bone density as great as those achieved with daily oral dosing with bisphosphonates with proven efficacy against fractures, suggesting that an annual infusion of zoledronic acid might be an effective treatment for postmenopausal osteoporosis.

Sintered dicalcium pyrophosphate increases bone mass in ovariectomized rats

Bisphosphonates are synthetic pyrophosphate analogs that can be used for the treatment of osteoporosis. Sintered dicalcium pyrophosphate, as a pyrophosphate analog, may be useful in the clinical setting for osteoporosis. In this study, an ovariectomized rat model is used to evaluate the effects of orally administered sintered dicalcium pyrophosphate on bone mass. Thirty-six female rats were used in this study. They randomly were divided into six groups: a negative normal control group, a positive osteoporosis control group, and ovariectomized groups treated either with alendronate sodium (one group) or sintered dicalcium pyrophosphate (three groups, each at a different level). The animals were sacrificed at 4 weeks after treatment. For all the rats, whole blood samples were obtained for the biochemical study. Bone ashes of long bones were measured and studied and histologic studies of cancellous bone were carried out. The ingestion of either alendronate or sintered dicalcium pyrophosphate did not have any deleterious effect on the major visceral organs. Ingestion of alendronate or sintered pyrophosphate decreased the bony porosity and increased bone mineral contents in the long bones of ovariectomized rats. Thus sintered dicalcium pyrophosphate can increase bone mass in the ovariectomized rat.

Update on alendronate for osteoporosis: once-weekly dosing

Alendronate (Fosamax, Merck & Co.) is now available in a 70 mg formulation to be taken once a week for osteoporosis. Earlier studies demonstrated that alendronate is highly effective for increasing bone density, reducing bone turnover rate and reducing the risk of fractures. A subsequent clinical trial reported that the once-weekly dosing regimen is therapeutically equivalent to the daily regimen. Administering alendronate (70 mg) once a week effectively provides continuous inhibition of bone resorption because bone resorption by osteoclasts is a slow process that typically requires 2-3 weeks for completion and alendronate remains at active bone remodelling sites for a sustained period and (when present in sufficient concentration) effectively inhibits bone resorption. Bisphosphonates are currently the pre-eminent therapy for osteoporosis. Once-weekly alendronate represents a major advance in convenience because oral bisphosphonates must be taken in the fasting state with water at least 30 minutes before consuming food or beverages. Sales data several months after introduction of once-weekly alendronate into the marketplace demonstrate rapid and extensive acceptance of this new regimen.

Treatment of osteoporosis with bisphosphonates

Bisphosphonates are safe and effective agents for treatment and prevention of osteoporosis. Alendronate and risedronate are the best studied of all agents for osteoporosis in terms of efficacy and safety. They increase bone mass. In patients who have established osteoporosis, they reduce the risk of vertebral fractures. They are the only agents shown in prospective trials to reduce the risk of hip fractures and other nonvertebral fractures. They are approved by the US FDA for prevention of bone loss in recently menopausal women, for treatment of postmenopausal osteoporosis, and for management of glucocorticoid-induced bone loss. Other bisphosphonates (e.g., etidronate for oral use, pamidronate for intravenous infusion) are also available and can be used off-label for patients who cannot tolerate approved agents. Bisphosphonates combined with estrogen produce greater gains in bone mass compared with either agent used alone; whether there is a greater benefit of combination therapy on fracture risk is not clear. Combining a bisphosphonate with raloxifene or calcitonin is probably safe, although data on effectiveness are lacking.

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.

Osteoporosis due to cancer treatment: pathogenesis and management

Many therapeutic regimens in cancer treatment carry the risk of causing or favoring the development of osteoporosis. Therapies in which hypogonadism may occur are most relevant in this respect. Prompt hormone replacement therapy is indicated in these patients. In patients in whom this is undesirable because of a hormone-dependent tumor, the risk of osteoporosis should be assessed by means of osteodensitometry, and prophylactic or therapeutic measures should be instituted if necessary. Early intervention improves outcome because osteoporosis therapy is most effective in preventing deterioration of bone mass. There remains much uncertainty in assessing the risk of combination chemotherapy with regard to the development of osteoporosis. Negative effects on the skeleton have, however, been demonstrated for individual drugs, such as methotrexate and ifosfamide. Negative effects of the tumor itself on bone metabolism may aggravate the degree of osteoporosis. Detailed data and long-term experience to assess the risk are urgently needed in this area and constitute an important research topic for the coming years and decades. This review discusses the most prevalent mechanisms of osteoporosis caused by cancer treatment and outlines therapeutic strategies for the prevention and treatment of therapy-induced bone loss.

Intermittent versus continuous clodronate administration in postmenopausal women with low bone mass

The aim of the study was to compare the effects on bone mass and turnover of continuous vs. intermittent clodronate administration on 120 postmenopausal women (average age 61 years) with low bone mass (femoral neck bone mineral density [BMD] of at least -1 SD or more, T-score), with another 30 women as a control group. Participants were given 1800 mg of clodronate every 6 months over 2 years using different treatment patterns: a) two continuous regimens, consisting of a daily oral dose of 400 mg or 100 mg every 10 days by intramuscular injection, the latter being considered continuous because the interval between injections is shorter than the time employed by each bone remodelling unit to complete the resorption phase of a remodelling cycle; and b) two intermittent regimens, consisting of 1800 mg every 6 months administered either as a single 18-h intravenous infusion or by separate infusions of 300 mg over 6 consecutive days. All women, including those in the control group, received calcium and vitamin D supplementation. After 2 years, continuous clodronate regimens caused an increase in BMD both at lumbar spine and proximal femur (L(1-4) BMD = 3.07% and 2.69%; femoral neck = 2.12% and 2.09%, respectively, with intramuscular and oral regimens). Intermittent clodronate administration was associated with a small increase or a stabilization in bone mass (L(1-4) BMD = 0.53% and 1.22%; femoral neck = 0.30% and 0.77%, respectively, with 1- and 6-day intravenous infusion regimens). From the 12th month, changes in spine and femoral neck BMD after continuous regimens were statistically different compared with that obtained with intermittent ones. Twenty-five of the 150 women (16.7%) discontinued the study before the end of the 2-year follow-up, but of these, only 7 dropped out because of adverse events related to the treatment itself. To summarize, intermittent clodronate administration could be a suitable option for the prevention of osteoporosis.

Weekly administration of alendronate: rationale and plan for clinical assessment

OBJECTIVE

This paper describes the rationale and supporting data for once-weekly dosing of alendronate.

BACKGROUND

Alendronate sodium, a bisphosphonate that potently inhibits bone resorption, has been shown to increase bone mass and substantially reduce the incidence of osteoporotic fractures, including fractures of the hip. The standard regimen of daily administration has generally been well tolerated. However, weekly administration may provide greater convenience to patients without compromising efficacy or tolerability. The pharmacokinetics of alendronate and bone remodeling theory predict similar efficacy for weekly and daily administration if the cumulative dose is the same. Bone resorption in individual remodeling units normally proceeds for approximately 2 weeks; alendronate inhibits the rate and extent of resorption. Because the half-life of residence on bone surfaces is several weeks, weekly administration of alendronate should inhibit bone resorption to an overall extent similar to that of daily dosing, thereby producing similar effects on bone mass and strength. Animal studies demonstrate that both weekly and daily parenteral administration of alendronate effectively increase bone mass and strength, but confirmation of efficacy is needed for weekly oral dosing in humans. Although daily bisphosphonates (alendronate and risedronate) elicited esophageal irritation in a canine model of gastroesophageal reflux, weekly dosing with alendronate at a higher unit dose did not. Thus, the lower frequency of weekly dosing with a higher unit dose may actually reduce the risk of upper gastrointestinal irritation compared with daily administration of a lower dose.

CONCLUSIONS

Current safety and efficacy data justify further investigation of once-weekly dosing of alendronate. Two positive-control, double-blind, randomized trials of osteoporosis treatment and prevention are currently being performed to assess the comparability of weekly, biweekly, and daily dosing of alendronate with regard to effects on bone density, safety, and tolerability.

Meta-analysis about efficacy of anti-resorptive drugs in post-menopausal osteoporosis

OBJECTIVE

The purpose of this study was to compare the effect of three groups of anti-resorptive drugs in post-menopausal osteoporosis.

DATA SOURCES

We collected data covering the period between 1983 and 1995, by first using MEDLINE. References retrieved were scanned further to identify additional papers.

STUDY SELECTION

Only randomized studies evaluating bone mass by means of dual-photon or dual energy densitometry over a period of 1 year were accepted.

DATA EXTRACTION

Studies were arranged into three drug groups. We used densitometry results after 1 year in all treatment or control groups. Factors which might interfere with the results were recorded for subsequent separate analysis.

DATA SYNTHESIS

The MEDLINE search identified almost 25,000 studies. On reading the abstracts, 275 trials appeared to be controlled trials and original copies were retrieved for detailed analysis. A total of 31 articles which satisfied the inclusion criteria were identified. The first meta-analysis included studies which compared oestrogens and placebo, and the global effect-size was 0.54 (95% CI 0.34, 0.73). The second meta-analysis compared calcitonins with placebo and produced an effect-size of 0.41 (95% CI 0.21, 0.61) The third analysis compared bisphosphonates and placebo and showed an effect-size of 0.87 (95% CI 0.68, 1.07). Only oestrogen dose affected the results found.

CONCLUSIONS

Bisphosphonates had the greatest effect on bone mass in post-menopausal osteoporosis.

Intravenous bisphosphonate prevents symptomatic osteoporotic vertebral collapse in patients after liver transplantation

Osteoporosis is common in patients with chronic cholestatic liver disease, and atraumatic spinal fracture is a recognized complication after orthotopic liver transplantation. Bisphosphonates are potent inhibitors of osteoclast bone resorption and have been successfully used to treat postmenopausal osteoporosis. We examined whether preoperative bone mineral density can predict the risk of fracture after orthotopic liver transplantation and whether intravenous bisphosphonate can prevent fractures in high-risk patients. Beginning in February 1993, standard bone mineral density measurements of the lumbar spine were performed as part of routine pretransplantation assessment. On the basis of a preliminary analysis from January 1995, patients with a lumbar spine bone mineral density of <0.84 g/cm2, or <84% of the predicted value (age/sex), were treated with intravenous bisphosphonate (pamidronate disodium) every 3 months before and for 9 months after liver transplantation. Bone mineral density measurements were available in 90 of 136 consecutive first transplants performed in our unit from February 1993 to September 1996. Before the use of pamidronate, 7 patients sustained symptomatic vertebral fractures. Their mean spine bone mineral density was lower than in the 38 patients with no clinical evidence of fracture (81.8% +/- 12.3% v 94.2% +/- 10.2%; P = .006). Since the introduction of pamidronate, no symptomatic vertebral fractures have occurred. Of 29 surviving patients with bone mineral density <0.84 g/cm2 before transplantation, 38% who did not receive treatment with pamidronate suffered spontaneous fracture, whereas 0 of 13 who received treatment suffered such a complication. A low lumbar spine bone mineral density is associated with a high risk of symptomatic vertebral fracture after liver transplantation. These results suggest that this risk is considerably reduced by the administration of intravenous bisphosphonate before and after transplantation.

Treatment of osteoporosis with bisphosphonates

Several bisphosphonates are effective for preventing bone loss associated with estrogen deficiency, glucocorticoid treatment, and immobilization, and for at least partially reversing bone loss in patients with postmenopausal osteoporosis and steroid-induced osteoporosis. The most promising of these agents are etidronate, alendronate, risedronate, and ibandronate. These drugs should have an important role in the prevention and treatment of osteoporosis; however, more research is needed regarding optimal doses and regimens (continuous versus intermittent, oral versus parenteral), comparisons with other agents, and their use in combination with other agents.

Bisphosphonates stimulate formation of osteoblast precursors and mineralized nodules in murine and human bone marrow cultures in vitro and promote early osteoblastogenesis in young and aged mice in vivo

Recent in vitro findings suggest that bisphosphonates, potent inhibitors of osteoclastic bone resorption, may also have a direct action on osteoblasts. The purpose of this study was to search for potential effects of etidronate and alendronate on the formation of early and late osteoblastic cell precursors by measuring the number of colony-forming units for fibroblasts (CFU-F) and colony-forming units for osteoblasts (CFU-OB) in murine and human bone marrow cultures. In murine marrow cultures, etidronate (10(-5) to 10(-9) mol/L) significantly stimulated the formation of CFU-F with a maximal effect at 10(-5) mol/L (mean increase over control values+/-SD: 106+/-17%;p < 0.001), whereas alendronate had a biphasic effect, being stimulatory at concentrations below 10(-7) mol/L (78+/-5%; p < 0.001), and inhibitory at higher doses. The formation of CFU-OB was also inhibited by both bisphosphonates at the highest concentrations (10(-5) mol/L and 10(-6) mol/L), but it was significantly stimulated at lower concentrations (from 10(-7) to 10(-9) mol/L for etidronate and 10(-7) to 10(-10) mol/I, for alendronate; p < 0.001). In human bone marrow cultures, alendronate (10(-8) to 10-(12) mol/L) increased CFU-F formation with a maximal effect at 10(-10) mol/L (161+/-12 %; p < 0.01). CFU-OB formation, observed only in the presence of dexamethasone (10(-8) mol/L), was markedly stimulated by alendronate at the above concentrations with a maximal increase at 10(-10) mol/L (133+/-34%; p < 0.001). The in vivo short-term effects of bisphosphonates on the formation of early osteoblast precursors were also studied in bone marrow cultures from young female mice treated with weekly subcutaneous injections of etidronate (0.3, 3, and 30 mg/kg) or alendronate (0.3, 3, and 30 microg/kg) and from aging female mice treated with the two lowest doses of both drugs. After 1 month of treatment, etidronate (0.3 and 3 mg/kg) and alendronate (0.3 and 3 microg/kg) significantly increased the number of CFU-F colonies in the bone marrow from young and old animals, whereas the highest dose of both drugs had no effect in young mice. Our results, together with previously reported observations of bone-forming effects in osteoporosis, suggest that bisphosphonates may have, in vivo, a potentially relevant influence on cells of the osteoblastic lineage, distinct from their inhibitory action on osteoclasts.

Alendronate/interleukin-1beta cotreatment increases interleukin-6 in bone and UMR-106 cells: dose dependence and relationship to the antiresorptive effect of alendronate

Aminobisphosphonates inhibit bone resorption but have been shown to elicit acute-phase-like elevations in interleukin-6 (IL-6) in bone in vitro. The current studies were carried out to determine the relationship between the antiresorptive effects of the aminobisphosphonate alendronate and its effects on IL-6. Resorption was elicited in cultured 19-day fetal rat limb bones by 72 h treatment with interleukin-1beta (IL-1beta). Bone mass was quantitated at the end of the culture period to assess resorption. IL-6 was determined by bioassay (7TD1 cell proliferation). IL-1beta (18 and 180 pM) stimulated bone resorption and increased IL-6. Alendronate (70 microM) inhibited the IL-1beta-stimulated resorption. Alendronate alone did not affect IL-6 production by the bones. The IL-6 production from bones stimulated with 18 pM IL-1beta was not significantly affected by alendronate, but the IL-6 production from bones stimulated with 180 pM IL-1beta plus alendronate (21 and 70 microM) was higher than with IL-1beta alone. Indomethacin (1 mM) inhibited the IL-6 increase elicited by 180 pM IL-1beta and the enhanced IL-6 production elicited by cotreatment with IL-1beta and alendronate. Since bone cultures contain multiple cell types, further experiments were carried out to determine whether alendronate could increase IL-1beta-stimulated IL-6 production in an osteoblast cell line, UMR-106. Alendronate alone did not affect IL-6 in UMR-106 cells. Alendronate (70 microM) in combination with IL-1beta (180, 1.8, or 8 nM), or 7 microM alendronate, in combination with 8 nM IL-1beta, significantly increased IL-6 in 48 h cell cultures. The results from the bone organ cultures show that alendronate can enhance IL-6 production elicited by higher concentrations of the cytokine IL-1beta in bone, but that this effect on IL-6 does not prevent the inhibitory actions of alendronate on bone resorption. The results with the UMR106 cells indicate that one cellular site at which this enhancement of IL-6 production can occur is the osteoblast.

A four-year randomized controlled trial of hormone replacement and bisphosphonate, alone or in combination, in women with postmenopausal osteoporosis

PURPOSE

Hormone replacement therapy (HRT) with estrogen and treatment with bisphosphonates have been shown to increase bone mineral density (BMD) in postmenopausal women. This 4-year prospective randomized study was carried out to assess the effectiveness of the combined HRT plus etidronate on BMD in postmenopausal women with established osteoporosis.

PATIENTS AND METHODS

Seventy-two postmenopausal women (mean age 64.9+/-0.5 years) attending metabolic bone disease outpatient clinics with established osteoporosis were randomly allocated into one of four treatment groups and monitored for 4 years. All patients enrolled in this study including the control group (n=18) received 1.0 g elemental calcium and 400 units vitamin D per day. The HRT group (n=18) received cyclical estrogen and progesterone; the etidronate group (n=17) received intermittent cyclical etidronate; and the combined therapy group (n=19) received both HRT and etidronate. BMD was measured in the lumbar spine and the hip before treatment and at 2 and 4 years after treatment. Changes in height were recorded, and the occurrence of new vertebral fractures were documented in comparison with the baseline radiographic evaluation. In 40 patients (10 patients per group), analysis of bone histomorphometry was carried out after 4 years of treatment.

RESULTS

In patients who received the combined therapy, BMD increased in the lumbar spine by 10.4% (P <0.001) and in the hip by 7.0% (P <0.001) at 4 years. For patients treated with ICE, these increases were 7.3% (P <0.001) and 0.9% (P <0.05), and with HRT, the increases were 7.0% (P <0.001) and 4.8% (P <0.01) in the vertebrae and femora, respectively. The group treated with calcium and vitamin D lost 2.5% (P <0.05) and 4.4% (P <0.01) of BMD in the vertebrae and femora, respectively, after 4 years. Patients who received combined therapy had significantly higher BMD in both the vertebrae and in the femora (P <0.05) in comparison with patients who were treated with HRT or etidronate alone after 4 years. In comparison with patients in the control group, there was a trend toward a lower rate of new vertebral fractures in the treatment groups. Height loss was significantly less in all three active treatment groups (HRT [P <0.001], etidronate [P <0.02], and combined therapy group [P <0.0001]), in comparison with the control group. The combined therapy group did not have a significant height loss, in comparison with the HRT (P <0.02) and the etidronate (P <0.001) groups. None of the patients had histomorphometric evidence of osteomalacia.

CONCLUSION

This 4-year randomized study showed an additive effect of etidronate and HRT on hip and spine BMD in postmenopausal women with established osteoporosis.

Three monthly intravenous injections of ibandronate in the treatment of postmenopausal osteoporosis

PURPOSE

Oral treatment of osteoporosis with bisphosphonates relies on compliance, the absorption being low and suppressed by simultaneous food intake. Intravenous (IV) treatment with an aminobisphosphonate, pamidronate (once every 3 months) was effective, but required infusions. Ibandronate, a new very potent aminobisphosphonate, can be administered safely as an IV bolus injection, and therefore offers an interesting alternative suitable for outpatient treatment.

PATIENTS AND METHODS

To test the efficacy of this bolus IV treatment in postmenopausal osteoporosis in randomized partly double-blind, placebo controlled study, 125 postmenopausal women (mean age, 64 years) with osteoporosis (bone mineral density [BMD] < -2.5 SD T score) received a placebo or ibandronate (0.25, 0.5, 1, or 2 mg) every 3 months. All patients received 1 g calcium/day. BMD, in g/cm2, was measured by dual-energy x-ray absorptiometry at all standard sites.

RESULTS

Lumbar spine BMD (L2 to L4) did not change (0.85%) in the placebo group, but increased by 2.4%, 3.5%, 3.7%, and 5.2% at 12 months for dose-ranging groups (no significant differences among ibandronate groups). The increase was statistically significantly different from placebo for the 0.5 mg (P < 0.006), 1 mg (P < 0.004), and 2 mg (P < 0.001) group, whereas with 0.25 mg no significant differences occured. After 1 year there were no significant changes in BMD compared with placebo at the femoral neck, Ward's triangle, and distal forearm. Total hip and trochanter BMD increased significantly, by 1.8% and 2.9% for total hip and by 2.7% and 4.2% for trochanter in the 1 and 2 mg group, respectively. Urinary excretion of C-telopeptide and N-telopeptide decreased after 1 month in all ibandronate groups, with a clear dose dependency. Three months after the first injection of 2 mg ibandronate there was still a significant reduction in these markers of bone resorption. Osteocalcin decreased progressively and dose dependently over time. There was a correlation between the decrease in C-telopeptide measured after 1 month and the increase in lumbar spine BMD after 1 year (n = 115, r = -0.26, P < 0.012). Ibandronate therapy proved to be safe. There was no significant difference in the overall number of adverse events in the ibandronate groups compared with the placebo group. Considering specific adverse events, no dose dependency and difference to placebo could be observed apart from acute reactions that occurred in 7% of the patients.

CONCLUSION

Treatment of postmenopausal osteoporosis by interval IV bolus injections of the bisphosphonate ibandronate was safe and effective in increasing BMD through a dose-dependent inhibition of bone resorption. The high potency of ibandronate allows 3-month interval bolus IV injections as a new therapeutic approach with optimal compliance.

Increments in bone mineral density of the lumbar spine and hip and suppression of bone turnover are maintained after discontinuation of alendronate in postmenopausal women

PURPOSE

Previously we have reported a significant increase in bone mineral density (BMD) of the spine and the hip and reductions in biochemical indices of bone turnover in postmenopausal women with osteoporosis treated with alendronate at various doses over 1 to 2 years. We have followed BMD and biochemical parameters in these patients for 1 or 2 years after discontinuation of alendronate to determine resolution of alendronate effects.

PATIENTS AND METHODS

Participants received daily oral doses of placebo, 5 or 10 mg of alendronate for 2 years, or 20 or 40 mg of alendronate for 1 year followed by 1 year of placebo. No treatment was given in the third year of study.

RESULTS

Lumbar spine BMD changes in the 5- and 10-mg groups (-1.4 and -0.4%) were similar to those in the placebo group (-1.2%) 1 year after discontinuation of drug and lumbar spine BMD changes in the 20- and 40-mg groups (-1.2% and 0.8%) were similar to those in the placebo group (-0.9%) 2 years after discontinuation of drug. BMD of the total hip followed the same pattern of resolution. The difference in BMD between alendronate and placebo groups at the end of alendronate treatment was maintained up to 2 years. Residual reductions in the bone resorption markers urinary deoxypyridinoline (D-Pyr) and collagen type 1 cross-linked N telopeptides and the bone formation markers serum bone-specific alkaline phosphatase and osteocalcin remained for 1 year after discontinuation of 5 and 10 mg of alendronate and for 2 years after discontinuation of 20 and 40 mg of alendronate, other than return of D-Pyr to baseline 1 year after cessation of treatment with the 5- and 10-mg doses.

CONCLUSIONS

A residual decrease in bone turnover may be found up to 2 years after discontinuation of alendronate. Accelerated bone loss is not observed when treatment is discontinued. However, continuous therapy with alendronate is required to achieve a continuous gain in BMD.

Alendronate prevents cyclosporin A-induced osteopenia in the rat

Post-transplantation bone disease is an increasingly recognized clinical entity whose etiology is multifactorial. The immunosuppressant agent cyclosporine-A (CsA) has repeatedly been shown experimentally to induce a high-turnover osteopenic state. Alendronate (Alen.) is a new generation bisphosphonate having far greater antiresorptive potency than previous bisphosphonates. It inhibits osteoclast resorption in vitro and in vivo without adversely affecting bone mineralization. This study was designed to investigate whether alendronate could prevent CsA-induced osteopenia in the rat. Forty-eight 8-month-old male Sprague Dawley rats were randomized into four groups to receive the following for 28 days: (1) CsA vehicle (veh.) p.o. daily and alendronate vehicle subcutaneously (s.c.) twice/week, (2) CsA 15 mg/kg p.o. daily and Alen. veh. s.c. twice/week, (3) Alen. 70 micrograms/kg s.c. twice/ week and CsA veh. p.o. daily, and (4) CsA 15 mg/kg p.o. daily and Alen. 70 micrograms/kg s.c. twice/week. Rats were weighed and bled and serum was assayed serially for calcium, PTH, 1,25(OH)2vit.D, and osteocalcin. Tibiae were removed following sacrifice on day 28, after double demeclocycline and calcein labeling, for histomorphometric analysis. Treated groups were compared to the vehicle-treated control. We confirmed previous findings that CsA produces elevated 1,25(OH)2 vitamin D and serum osteocalcin levels. Alendronate treatment by itself decreased osteocalcin by day 28 and resulted in a marginal decrease in serum total calcium on day 14. The histomorphometry findings reconfirmed that the administration of CsA induces a state of high-turnover osteopenia. Alendronate prevented CsA's adverse effects, particularly in maintaining trabecular bone volume, presumably by decreasing bone remodeling. Alendronate would seem to hold therapeutic promise in post-transplantation bone disease.

Pharmacokinetics of pamidronate disodium in patients with cancer with normal or impaired renal function

Pamidronate is a second-generation bisphosphonate that undergoes negligible biodegradation and is eliminated exclusively by renal excretions. Nineteen cancer patients were stratified according to baseline creatinine clearance (Clcr): group I, Clcr > 90 mL/min (n = 6); group II, Clcr 61 mL/min to 90 mL/min (n = 6); group III, Clcr 30 mL/min to 60 mL/min (n = 3); group IV, Clcr < 30 mL/min (n = 4). All patients received a single, 90-mg dose of pamidronate disodium administered in a 4-hour intravenous infusion. Plasma and urine samples were collected at intervals up to 36 and 120 hours, respectively, after the start of infusion and were assayed for pamidronate, using validated high-performance liquid chromatography. Pamidronate's pharmacokinetics were characterized by a short distribution phase (2-3 hours) followed by rapid elimination of the drug in urine. Elimination of pamidronate was slower in patients in group IV with a mean +/- standard deviation area under the plasma concentration-time curve (AUC0-36) of 19.0 +/- 4.60 micrograms.hr/mL compared with 8.1 +/- 3.13 micrograms.hr/mL in patients in group I. A linear relationship in Clcr was observed for AUC0-36 (r = 0.67), urinary excretion (r = 0.69), and renal clearance (r = 0.81). Renal clearance was proportional to Clcr for patients in all four renal-function groups. In the treatment of bone metastases of malignancy, successive doses of pamidronate are generally separated by weeks; thus, plasma accumulation in patients with renal impairment is not expected to be clinically relevant. A reduction in dose of pamidronate disodium should not be necessary in cancer patients with renal impairment.

Bisphosphonates: preclinical aspects and use in osteoporosis

The bisphosphonates are synthetic compounds characterized by a P-C-P bond. They have a strong affinity to calcium phosphates and hence to bone mineral. In vitro they inhibit both formation and dissolution of the latter. Many of the bisphosphonates inhibit bone resorption, the newest compounds being 10,000 times more active than etidronate, the first bisphosphonate described. The antiresorbing effect is cell mediated, partly by a direct action on the osteoclasts, partly through the osteoblasts, which produce an inhibitor of osteoclastic recruitment. When given in large amounts, some bisphosphonates can also inhibit normal and ectopic mineralization through a physical-chemical inhibition of crystal growth. In the growing rat the inhibition of resorption is accompanied by an increase in intestinal absorption and an increased balance of calcium. Bisphosphonates also prevent various types of experimental osteoporosis, such as after immobilization, ovariectomy, orchidectomy, administration of corticosteroids, or low calcium diet. The P-C-P bond of the bisphosphonates is completely resistant to enzymatic hydrolysis. The bisphosphonates studied up to now, such as etidronate, clodronate, pamidronate, and alendronate, are absorbed, stored, and excreted unaltered. The intestinal absorption of the bisphosphonates is low, between 1% or less and 10% of the amount ingested. The newer bisphosphonates are at the lower end of the scale. The absorption diminishes when the compounds are given with food, especially in the presence of calcium. Bisphosphonates are rapidly cleared from plasma, 20%-80% being deposited in bone and the remainder excreted in the urine. In bone, they deposit at sites of mineralization as well as under the osteoclasts. In contrast to plasma, the half-life in bone is very long, partially as long as the half-life of the bone in which they are deposited. In humans, bisphosphonates are used successfully in diseases with increased bone turnover, such as Paget's disease, tumoural bone disease, as well as in osteoporosis. Various bisphosphonates, such as alendronate, clodronate, etidronate, ibandronate, pamidronate, and tiludronate, have been investigated in osteoporosis. All inhibit bone loss in postmenopausal women and increase bone mass. Furthermore, bisphosphonates are also effective in preventing bone loss both in corticosteroid-treated and in immobilized patients. The effect on the rate of fractures has recently been proven for alendronate. In humans, the adverse effects depend upon the compound and the amount given. For etidronate, practically the only adverse effect is an inhibition of mineralization. The aminoderivatives induce for a period of 2-3 days a syndrome with pyrexia, which shows a similitude with an acute phase reaction. The more potent compounds can induce gastrointestinal disturbances, sometimes oesophagitis, when given orally. Bisphosphonates are an important addition to the therapeutic possibilities in the prevention and treatment of osteoporosis.

Short-term intravenous bisphosphonates in prevention of postmenopausal bone loss

This study was performed to test the efficacy of short-term intravenous clodronate and etidronate in the prevention of postmenopausal bone loss. Healthy postmenopausal women, exhibiting a decreasing trend in bone mineral density, were randomized to five groups (clodronate at doses of 150, 300, and 600 mg; etidronate at a dose of 300 mg; and a placebo group) of 21-22 subjects. The drugs were administered intravenously three times with 1-week intervals, followed by regular evaluation for up to 24 months. During the first year, 300 mg of clodronate retarded bone loss significantly in the lumbar spine and femoral neck, where significant protection still persisted after 24 months. Other doses of clodronate (150 and 600 mg) were not bone protective. Etidronate (300 mg) retarded bone loss significantly in the lumbar spine up to 24 months, relative to placebo. Serum concentrations of procollagen I carboxy-terminal propeptide and urinary Ca2+ and hydroxyproline excretion decreased in all bisphosphonate groups during the first month after treatment, but the values returned later toward baseline. In the etidronate-group, serum osteocalcin concentrations also decreased significantly during the first 3 months of the study. Otherwise, no uniform serum responses to bisphosphonate-treatment were detected in circulating markers of bone formation, alkaline phosphatase, or osteocalcin. No significant differences in the serum concentrations of cross-linked carboxy-terminal telopeptide of type I collagen were detected between the groups. Patient acceptance of both bisphosphonates was excellent, and no drug-related adverse side effects were detected. These results suggest that infrequently repeated intravenous treatment with bisphosphonates may effectively counteract postmenopausal bone loss.

Intravenous administration of alendronate counteracts the in vivo effects of glucocorticoids on bone remodeling

The purpose of the investigation was to test the use of alendronate in the therapy of children affected by chronic rheumatic diseases and symptomatic drug-induced osteoporosis. Two courses of alendronate were intravenously administered to four girls with vertebral fractures that were glucocorticoid induced. Improvement of back pain and bone mineral density increase evaluated by DXA and conventional spine X-rays were observed. Our study supports the ABD-induced improvement of the negative effects of long-term therapy on bone mineral density in children with chronic rheumatic diseases.

Alendronate treatment for osteoporosis: a review of the clinical evidence

Bisphosphonates have recently gained an increasing role in the management of osteoporosis. The aminobisphosphonate, alendronate has recently been introduced as a new agent for the treatment of postmenopausal osteoporosis. This paper reviews the clinical evidence for the use of this agent and seeks to assess its place in osteoporosis management.

Studies of the oral bioavailability of alendronate

Clinical studies were performed to examine the oral bioavailability of alendronate (4-amino-1-hydroxy-butylidene-1,1-bisphosphonate monosodium). All studies, with the exception of one performed in men, involved postmenopausal women. Short-term (24 to 36 hours) urinary recovery of alendronate after an intravenous dose of 125 to 250 micrograms averaged about 40% in both men and women. In women, oral bioavailability of alendronate was independent of dose (5 to 80 mg) and averaged (90% confidence interval) 0.76% (0.58, 0.98) when taken with water in the fasting state, followed by a meal 2 hours later. Bioavailability was similar in men [0.59%, (0.43, 0.81)]. Taking alendronate either 60 or 30 minutes before a standardized breakfast reduced bioavailability by 40% relative to the 2-hour wait. Taking alendronate either concurrently with or 2 hours after breakfast drastically (> 85%) impaired availability. Black coffee or orange juice alone, when taken with the drug, also reduced bioavailability (approximately 60%). Increasing gastric pH, by infusion of ranitidine, was associated with a doubling of alendronate bioavailability. A practical dosing recommendation, derived from these findings and reflective of the long-term nature of therapy for a disease such as osteoporosis, is that patients take the drug with water after an overnight fast and at least 30 minutes before any other food or beverage.

The role of bisphosphonates in the prevention and treatment of osteoporosis

The first-generation biphosphonate etidronate is used only experimentally in osteoporosis prevention. Its effects in treating osteoporosis have been studied only in subjects who already have vertebral crush fractures. No reduction in the incidence of fractures in this population as a whole has been established. The suggestion of a more pronounced beneficial effect seen in severely osteoporotic patients treated with bisphosphonates for two years that seems to emerge from a posteriori analysis must be confirmed. The long-term safety of this therapy is currently under study. Subsequent generations of bisphosphonates are still experimental, whether for prevention or treatment.

Combined therapy with estrogen and etidronate has an additive effect on bone mineral density in the hip and vertebrae: four-year randomized study

BACKGROUND

Administration of estrogen or etidronate has been shown to increase bone mineral density in postmenopausal women. This 4-year, prospective, randomized study was carried out to monitor any added beneficial effect on bone mineral density when hormone-replacement therapy (HRT) was combined with etidronate.

PATIENTS AND METHODS

Fifty-eight early postmenopausal women attending metabolic bone disease outpatient clinics were randomly allocated into four treatment groups and monitored for up to 4 years. All patients received 1.0 g/d of elemental calcium. In addition, group 1 received percutaneously administered HRT (n = 15); group 2, intermittent cyclical etidronate (ICE) (n = 14); group 3, HRT and ICE (n = 15); and group 4, calcium alone (n = 14). The bone mineral density (measured by dual-energy x-ray absorptiometry), biochemical variables of bone turnover, including bone-specific alkaline phosphatase, and urinary hydroxyproline:creatinine ratios were measured before treatment and at 2 and 4 years after treatment.

RESULTS

In patients who received the combined therapy, bone mineral density was increased in the vertebrae by 10.9% (P < 0.001) and in the femora by 7.25% (P < 0.001) at 4 years. For patients treated with ICE, the increase was 6.79% (P < 0.001) and 1.20% (P < 0.05), and with HRT, 6.78% (P < 0.001) and 4.01% (P < 0.01) in the vertebrae and femora, respectively. The group treated with calcium alone lost 3.81% (P < 0.01) and 4.96% (P < 0.01) of bone mineral density in vertebrae and femora. Patients who received no specific therapy lost 8.58% (P < 0.01) from vertebrae, and 7.83% (P < 0.01) from the femora over 4 years. Patients who received combined therapy had significantly higher bone mineral density in both vertebrae (P < 0.05) and femora (P < 0.01), in comparison to patients who were treated with HRT, or ICE, alone. Three of 9 patients (33%) in the ICE group developed osteomalacia, as shown by bone histomorphometry, whereas in women who received combined HRT and ICE therapies, none of the 11 patients tested had evidence of bone mineralization defects.

CONCLUSION

This 4-year, prospective, randomized study in early postmenopausal women showed an additive effect of ICE and HRT on the bone mineral density in both vertebrae and the hip. Furthermore, the combined therapy prevented the occurrence of osteomalacia associated with etidronate. This is the first study to demonstrate the effects of etidronate in early postmenopausal women, and the additive beneficial effects of HRT and ICE on bone mineral density.

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.

Comparison of alendronate and sodium fluoride effects on cancellous and cortical bone in minipigs. A one-year study

Fluoride stimulates trabecular bone formation, whereas bisphosphonates reduce bone resorption and turnover. Fracture prevention has not been convincingly demonstrated for either treatment so far. We compared the effects of 1-yr treatment of 9-mo-old minipigs with sodium fluoride (NaF, 2 mg/kg/d p.o.) or alendronate (ALN, 4 amino-1-hydroxybutylidene bisphosphonate monosodium, 1 mg/kg/d p.o.) on the biomechanical and histomorphometric properties of pig bones. As expected, NaF increased and ALN decreased bone turnover, but in these normal animals neither changed mean bone volume. NaF reduced the strength of cancellous bone from the L4 vertebra, relative to control animals, and the stiffness (resistance to deformation) of the femora, relative to the ALN group. In the ALN-treated animals, there was a strong positive correlation between bone strength and L5 cancellous bone volume, but no such correlation was observed in the NaF group. Furthermore, the modulus (resistance to deformation of the tissue) was inversely related to NaF content and there was a relative decrease in bone strength above 0.25 mg NaF/g bone. Moreover, within the range of changes measured in this study, there was an inverse correlation between bone turnover, estimated as the percentage of osteoid surface, and modulus. These findings have relevant implications regarding the use of these agents for osteoporosis therapy.

Rationale for the use of alendronate in osteoporosis

Bisphosphonates are being used in disorders associated with accelerated resorption of bone, particularly Paget's disease of bone and the bone disease of malignancy. Their undoubted biological efficacy and relatively low apparent toxicity make them attractive candidates for the management of osteoporosis. The bisphosphonate alendronate has many characteristics which suggest that it is suitable for use in osteoporosis. It is a potent inhibitor of osteoclast-mediated bone resorption with no adverse effect on the mineralization of bone. Earlier studies have shown it to be one of the most active bisphosphonates in Paget's disease and the hypercalcemia of malignancy. In common with other bisphosphonates tested thus far, alendronate appears to inhibit bone loss in a variety of experimental models of osteoporosis. Long-term studies are needed to determine its steady-state effects on bone mass in man. Most data indicate that alendronate is capable at least of decreasing the rate of bone loss, and might even induce increments in bone mass for many years. Since the experimental studies show that the increase in bone mass observed with alendronate is associated with an increase in bone strength, its use is likely to decrease the frequency of fractures. However, direct clinical evidence for this requires the outcome of well-designed long-term prospective studies.

Two years' effectiveness of intravenous pamidronate (APD) versus oral fluoride for osteoporosis occurring in the postmenopause

Bisphosphonates seem to be effective as antiresorptive agents in the prevention and treatment of osteoporosis. However, the optimal dose and route of administration as well as the specific effects on cortical or trabecular bone have not been clarified. To compare pamidronate (APD) with fluoride (F) in the therapy of postmenopausal osteoporosis, 32 osteoporotic women were treated for 2 years either with APD (30 mg as a single intravenous infusion over 1 h every 3 months, n = 16, mean age 65 years) or with fluoride orally (20-30 mg F/day, n = 16, mean age 67 years) in an open study. Both groups received 1 g calcium and 1000 U vitamin D per day, but no estrogens or other drugs acting on bone. Both groups showed the same initial mean number of fractures per patient (2.8 and 2.7). Bone densitometry was performed every 6 months at three sites: lumbar spine and hip with dual-energy X-ray absorptiometry (BMD), distal forearm with single photon absorptiometry and lumbar spine with quantitative computed tomography. Biochemical assessment was performed in blood and urine every 3 months. Lumbar BMD (g/cm2, mean +/- SEM) increased from 0.632 (+/- 0.030) at time 0 to 0.696 (+/- 0.028) at 24 months in the APD group (p < 0.001), and from 0.684 (+/- 0.025) to 0.769 (+/- 0.028) in the fluoride group (p < 0.001). Femoral neck BMD increased significantly from 0.558 (+/- 0.025) to 0.585 (+/- 0.025) (p < 0.01) in the APD group, whereas it did not change in the fluoride group.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of 2-year treatment with the aminobisphosphonate alendronate on bone metabolism, bone histomorphometry, and bone strength in ovariectomized nonhuman primates

This study examined the effect of 2 yr of treatment with the aminobisphosphonate alendronate (ALN) (0.05 or 0.25 mg/kg i.v. ALN every 2 wk) on estrogen deficiency bone loss and bone strength changes in ovariectomized (OVX) baboons (n = 7 per group) and the ALN mode of action at the tissue level. Biochemical markers of bone turnover increased in OVX animals and were maintained by ALN treatment at non-OVX levels (low dose) or below (high dose). 2 yr of treatment produced no cumulative effects on bone turnover markers. Histomorphometry showed a marked increase in cancellous bone remodeling in OVX animals. Activation frequency increased from 0.48 to 0.86 per yr (L5 vertebra), and the osteoid surfaces from 9 to 13.5% (P < 0.05). No changes were observed in eroded and osteoclast surfaces. ALN treatment decreased activation frequency and indices of bone formation to control levels (low dose) or below (high dose), did not change indices of mineralization, and increased bone mineral density (BMD) in the lumbar vertebrae (L2-L4) by 15% at 0.25 mg/kg (P < 0.05), relative to vehicle-treated animals. The mean strength of cancellous bone (L4) increased by 44% (low ALN dose) and 100% (high dose), compared with vehicle. The strength of individual bones correlated with the square of the L2-L4 BMD (r = 0.91, P < 0.0034). In conclusion, ALN treatment reversed the effects of ovariectomy on cancellous bone turnover and increased bone mass and bone strength in baboons.

Clinical effects of bisphosphonates in involutional osteoporosis

The bisphosphonates are analogs of naturally occurring pyrophosphate. They appear to block bone resorption much more than mineralization. A series of compounds has been investigated. These have antiresorptive potencies ranging from 1 to 10,000. So far, structure-function relationships have eluded definition. These drugs increase the bone density in women with postmenopausal osteoporosis by about 5%-10% over 1 year. The bone density then appears to plateau, but most studies are of short duration. Improved bone density does not necessarily result in stronger bone, but no studies have had adequate power to assess fracture incidence. Bone formation rates decrease as measured histomorphometrically. This occurs while the bone density is improving, which implies an inhibition of bone resorption that is probably due to direct toxicity to the osteoclasts. Etidronate blocks mineralization as well as resorption and can cause osteomalacia, which is not seen with low-dose cyclical etidronate or with the second-generation compounds. The long-term effects of interfering with the remodeling cycle are still not known. Subtle side effects may be those on the bone itself. These might go undetected, since bone pain or fractures usually are attributable to the underlying disease.

The role of bisphosphonates in the prevention and treatment of osteoporosis

Bisphosphonates are synthetic compounds that are taken up preferentially by the skeleton and suppress osteoclast-mediated bone resorption. There are structural differences among the various bisphosphonates that account for considerable differences in antiresorptive potencies and in activity/toxicity ratios. Bisphosphonates are given to patients with established vertebral osteoporosis, either intermittently or continuously, but controlled, long-term data are only available for intermittent regimens. They decrease the rate of bone loss, increase spinal bone mineral density (BMD), and stabilize BMD for at least 4 years of treatment without any significant side effects. This increase in bone mass is not due to redistribution of calcium in the skeleton, as at sites with predominantly cortical bone, BMD values either do not change or increase with treatment. Bisphosphonates also appear to decrease the frequency of new vertebral fractures in some patients with established osteoporosis, but this effect needs to be verified. Other issues that need to be addressed include the optimal mode and dose of administration and hence the choice of bisphosphonate, the duration of treatment, the changes in bone metabolism following treatment arrest, and finally the efficacy of bisphosphonates in the prevention of hip fractures.