Zoledronic Acid for the Prevention of Bone Loss in Postmenopausal Women With Low Bone Mass: A Randomized Controlled Trial

Comparative gastrointestinal safety of bisphosphonates in primary osteoporosis: a network meta-analysis

We completed a network meta-analysis of published papers to compare bisphosphonate gastrointestinal safety. We found that zoledronic acid had the highest chance of causing gastrointestinal adverse events. Etidronate had the highest chance of discontinuation due to an adverse event. No difference was found for serious adverse events.

INTRODUCTION

Bisphosphonates are first-line treatment for osteoporosis. Gastrointestinal (GI) adverse events (AE) are the primary reason for non-adherence. Little is known about the comparative GI safety of bisphosphonates.

PURPOSE

Leverage published clinical trial data to examine the comparative GI safety of bisphosphonates.

METHODS

We completed a systematic review of all English-language clinical trials that assessed bisphosphonate safety and/or efficacy in primary osteoporosis through to 2012. Randomized, blinded, and controlled studies were eligible. The primary outcome was any GI-related AE. Subanalyses were completed for upper GI symptoms, serious GI, nausea, esophageal-related events, and discontinuation due to AE. A Bayesian-based network meta-analysis was completed to allow for indirect comparisons. Results were reported as the probability that a specific drug had the highest number of events.

RESULTS

We identified 50 studies: 32 alendronate, 12 risedronate, 5 etidronate, and 7 zoledronic acid. Zoledronic acid had the highest probability of having the highest number of any GI AE (91%) and nausea (70%). Etidronate (70%) and zoledronic acid (28%) had the highest probability of having the greatest attrition due to AE. Etidronate had the highest probability (56%) of having the greatest number of upper GI symptoms among oral bisphosphonates.

CONCLUSION

Zoledronic acid had the highest probability of causing the greatest number of GI AE, possibly related to nausea. These results question the assumption that annual zoledronic acid will translate into better adherence. Little difference was found between alendronate and risedronate for serious AE. More research into real-world implications of the comparative safety of bisphosphonates is needed.

Duration of antiresorptive effects of low-dose zoledronate in osteopenic postmenopausal women: a randomized, placebo-controlled trial

Annual intravenous administration of 5 mg zoledronate decreases fracture risk, but the optimal dosing regimen for zoledronate has not been determined. We set out to evaluate the antiresorptive effects of a single administration of lower doses of zoledronate. A total of 180 postmenopausal women with osteopenia enrolled in a double-blind, randomized, placebo-controlled trial over 2 years at an academic research center. Participants were randomized to a single baseline administration of intravenous zoledronate in doses of 1 mg, 2.5 mg, or 5 mg, or placebo. The primary endpoint was change in bone mineral density(BMD) at the lumbar spine. Secondary endpoints were change in BMD at the proximal femur and total body, and changes in biochemical markers of bone turnover. After 2 years, the change in spine BMD was greater in each of the zoledronate groups than in the placebo group; values are mean (95% confidence interval [CI]) difference versus placebo: zoledronate 1 mg 4.4% [2.7% to 6.1%]; 2.5 mg 5.5% [3.9% to 7.2%]; 5 mg 5.3% [3.8% to 6.7%], p < 0.001 for each dose). Change in BMD at the total hip was greater in each of the zoledronate groups than the placebo group (mean [95% CI] difference versus placebo: zoledronate 1 mg 2.6% [1.5% to 3.7%]; 2.5 mg 4.4% [3.5% to 5.3%]; 5 mg 4.7% [3.7% to 5.7%], p < 0.001 for each dose). Each of the bone turnover markers, β-C-terminal telopeptide of type I collagen (β-CTX) and procollagen type-I N-terminal propeptide (P1NP), was lower in each of the 2.5-mg and 5-mg zoledronate groups than the placebo group throughout the trial (p < 0.001 versus placebo for each marker for each dose at each time point). For each endpoint, changes were similar in the 2.5-mg and 5-mg zoledronate groups, whereas those in the 1-mg group were smaller than those in the other zoledronate groups. These data demonstrate that single administrations of zoledronate 1 mg or 2.5 mg produce antiresorptive effects that persist for at least 2 years. Trials assessing the antifracture efficacy of intermittent low doses of zoledronate, in particular the 2.5-mg dose, are justified.

Effect of zoledronic acid on reducing femoral bone mineral density loss following total hip arthroplasty: preliminary results of a prospective randomized trial

This randomized trial evaluated the effect of zoledronic acid on femoral bone mineral density (BMD) following primary total hip arthroplasty. Bone mineral density was compared for up to 2years in 27 patients receiving 5mg zoledronic acid intravenous infusion and in 24 patients receiving placebo at 2weeks and 1year after surgery. Zoledronic acid prevented loss of bone mineral density at 1year (+13.8% vs +1.4%, P=.0065) and 2years (+14.3% vs -4.0%, P<.0001) in Gruen zone 1, at 1year (-8.4% vs -25.4%, P<.0001) and 2years (-9.6% vs -27.3%, P<.0001) in Gruen zone 7, at 6weeks, 6months, and 1 or 2years in Gruen zones 4 and 6. For all Gruen zones, prevention of BMD loss by ZOL was significant at 6weeks, 6months, 1year (+0.80% vs -6.03%, P<.0001) and 2years (-0.16% vs -7.13%, P<.0001).

Five years of anti-resorptive activity after a single dose of zoledronate--results from a randomized double-blind placebo-controlled trial

Intravenous zoledronate 5 mg, administered annually, prevents fractures in people with osteoporosis, but the optimal dosing schedule is not known. Previously, we reported that a single dose of 5 mg zoledronate stably decreased bone turnover and increased bone mineral density (BMD) for 3 years in a randomized controlled trial in 50 postmenopausal women with osteopenia. We have now completed a 2-year double-blind extension of this trial, during which no additional treatment was administered. The primary endpoint was change in the bone turnover markers procollagen type-I N-terminal propeptide (P1NP) and β-C-terminal telopeptide of type I collagen (β-CTX); the secondary endpoint was change in BMD at lumbar spine, total hip and total body. Mean levels of the each of the bone turnover markers were lower in the zoledronate group throughout the study (P<0.0001 for each marker). After 5 years, mean (95% CI) levels of β-CTX and P1NP were 277 ng/L (150, 404) and 28 μg/L (16, 40) lower in the zoledronate group, corresponding to reductions of 48% and 45%, respectively. BMD was higher in the zoledronate group during the study (P<0.0001 for each site). After 5 years, BMD in the zoledronate group was higher by 4.2% (1.1, 7.2) at the lumbar spine, by 5.3% (2.7, 7.9) at the total hip, and by 2.7% (1.1, 4.2) at the total body. These findings suggest that the anti-resorptive effects of a single 5 mg dose of zoledronate persist for at least 5 years in postmenopausal women. Trials assessing the anti-fracture efficacy of dosing intervals of zoledronate of up to 5 years are justified.

Effects of intravenous zoledronate on bone turnover and bone density persist for at least five years in HIV-infected men

CONTEXT

In HIV-infected men, the antiresorptive effects of zoledronate persist for at least 2 yr after the second annual dose.

OBJECTIVE

Our objective was to determine the duration of action of zoledronate in men.

DESIGN AND SETTING

This was 4-yr extension of a 2-yr, double-blind, randomized, placebo-controlled trial at an academic research center.

PARTICIPANTS

Participants included 43 HIV-infected men with bone mineral density (BMD) T score below -0.5, 35 of whom entered the extension study.

INTERVENTION

Intervention was annual administration of 4 mg iv zoledronate or placebo at baseline and 1 yr and no intervention subsequently.

MAIN OUTCOME MEASURES

We evaluated changes in the bone turnover markers, serum osteocalcin and serum C-telopeptide (CTx), and changes in BMD at the lumbar spine, total hip, and total body.

RESULTS

There was no time × treatment interaction between 1 and 5 yr after the second zoledronate dose for osteocalcin or CTx (P > 0.4) or any BMD site (P > 0.7). Between 1 and 5 yr after the second dose, on average, osteocalcin was 41% lower (95% confidence interval = 19-62%; P < 0.001), CTx 52% lower (33-71%; P < 0.001), lumbar spine BMD 3.7% greater (0.3-7.0%; P = 0.03), total hip BMD 2.3% greater (0.3-4.3%; P = 0.02), and total body BMD 2.5% greater (0.8-4.1%; P = 0.004) in the zoledronate group than the placebo group. Five years after the second dose, the between-groups differences were 38% (13-62%) for osteocalcin, 49% (20-77%) for CTx, 3.5% (0.7-6.7%) for lumbar spine BMD, 3.4% (1.4-5.4%) for total hip BMD, and 1.6% (0.2-3.1%) for total body BMD.

CONCLUSION

The effects of two annual 4-mg doses of zoledronate in men persist for at least 5 yr after the second dose. Larger trials assessing the antifracture efficacy of less frequent dosing of zoledronate are justified.

Reduction of urinary levels of N-telopeptide correlates with treatment compliance in women with postmenopausal osteoporosis receiving alendronate

OBJECTIVE

The aim of this study was to assess the factors associated with the effectiveness of treatment with alendronate (ALN) quantified by a reduction in urinary excretion of N-telopeptide (NTx).

METHODS

The study is an observational, prospective, multicenter trial, with a 6-month follow-up. Postmenopausal osteoporotic women (densitometric criteria), who initiated treatment with ALN (70 mg/weekly) without previous treatment with antiresorptive agents (12 month) and calcitonin (6 month), were included. The assessment of NTx levels (nmol bone collagen equivalents/mmol creatinine) in the urine was performed at baseline and after completion of follow-up. A logistic regression model included "achieving a reduction in urinary NTx of at least 30% (minimal clinically significant change [MCSC])" as a dichotomous dependent variable and the following as independent variables: baseline urinary NTx levels, treatment compliance, years since diagnosis of menopause, ALN treatment duration, and treatment with calcium and vitamin D. Treatment compliance was assessed as the percentage of days of medication prescribed as a function of the time between the beginning and end of treatment. Good compliance was defined as a percentage between 80% and 120%.

RESULTS

The variables that reached statistical significance were baseline urinary NTx values (odds ratio, 1.052; 95% CI, 1.025-1.079) and compliance (odds ratio, 3.9; 95% CI, 1.5-10.1). Therefore, the women with good treatment compliance were almost 4 times more likely to achieve an MCSC in NTx levels, and the raise in one unit of urinary NTx baseline values increased by 5% of the probability of achieving MCSC.

CONCLUSIONS

Treatment with ALN (70 mg/week) in women with postmenopausal osteoporosis effectively reduces the urinary excretion of the bone turnover biomarker NTx. The probability of achieving a clinically significant reduction is greater in those women with higher baseline levels of NTx and in women who comply with treatment.

Postmenopausal osteoporosis treatment with antiresorptives: effects of discontinuation or long-term continuation on bone turnover and fracture risk--a perspective

Osteoporosis may be a lifelong condition. Robust data regarding the efficacy and safety of both long-term osteoporosis therapy and therapy discontinuation are therefore important. A paucity of clinical trial data regarding the long-term antifracture efficacy of osteoporosis therapies necessitates the use of surrogate endpoints in discussions surrounding long-term use and/or discontinuation. Long-term treatment (beyond 3-4 years) may produce further increases in bone mineral density (BMD) or BMD stability, depending on the specific treatment and the skeletal site. Bisphosphonates, when discontinued, are associated with a prolonged reduction in bone turnover markers (BTMs), with a very gradual increase to pretreatment levels within 3 to 60 months of treatment cessation, depending on the bisphosphonate used and the prior duration of therapy. In contrast, with nonbisphosphonate antiresorptive agents, such as estrogen and denosumab, BTMs rebound to above pretreatment values within months of discontinuation. The pattern of BTM change is generally mirrored by a more or less rapid decrease in BMD. Although the prolonged effect of some bisphosphonates on BTMs and BMD may contribute to residual benefit on bone strength, it may also raise safety concerns. Adequately powered postdiscontinuation fracture studies and conclusive evidence on maintenance or loss of fracture benefit is lacking for bisphosphonates. Similarly, the effects of rapid reversal of bone turnover upon discontinuation of denosumab on fracture risk remain unknown. Ideally, studies evaluating the effects of long-term treatment and treatment discontinuation should be designed to provide head-to-head "offset" data between bisphosphonates and nonbisphosphonate antiresorptive agents. In the absence of this, a clinical recommendation for physicians may be to periodically assess the benefits/risks of continuation versus discontinuation versus alternative management strategies.

The effect of 3 versus 6 years of zoledronic acid treatment of osteoporosis: a randomized extension to the HORIZON-Pivotal Fracture Trial (PFT)

Zoledronic acid 5 mg (ZOL) annually for 3 years reduces fracture risk in postmenopausal women with osteoporosis. To investigate long-term effects of ZOL on bone mineral density (BMD) and fracture risk, the Health Outcomes and Reduced Incidence with Zoledronic acid Once Yearly-Pivotal Fracture Trial (HORIZON-PFT) was extended to 6 years. In this international, multicenter, double-blind, placebo-controlled extension trial, 1233 postmenopausal women who received ZOL for 3 years in the core study were randomized to 3 additional years of ZOL (Z6, n = 616) or placebo (Z3P3, n = 617). The primary endpoint was femoral neck (FN) BMD percentage change from year 3 to 6 in the intent-to-treat (ITT) population. Secondary endpoints included other BMD sites, fractures, biochemical bone turnover markers, and safety. In years 3 to 6, FN-BMD remained constant in Z6 and dropped slightly in Z3P3 (between-treatment difference = 1.04%; 95% confidence interval 0.4 to 1.7; p = 0.0009) but remained above pretreatment levels. Other BMD sites showed similar differences. Biochemical markers remained constant in Z6 but rose slightly in Z3P3, remaining well below pretreatment levels in both. New morphometric vertebral fractures were lower in the Z6 (n = 14) versus Z3P3 (n = 30) group (odds ratio = 0.51; p = 0.035), whereas other fractures were not different. Significantly more Z6 patients had a transient increase in serum creatinine >0.5 mg/dL (0.65% versus 2.94% in Z3P3). Nonsignificant increases in Z6 of atrial fibrillation serious adverse events (2.0% versus 1.1% in Z3P3; p = 0.26) and stroke (3.1% versus 1.5% in Z3P3; p = 0.06) were seen. Postdose symptoms were similar in both groups. Reports of hypertension were significantly lower in Z6 versus Z3P3 (7.8% versus 15.1%, p < 0.001). Small differences in bone density and markers in those who continued versus those who stopped treatment suggest residual effects, and therefore, after 3 years of annual ZOL, many patients may discontinue therapy up to 3 years. However, vertebral fracture reductions suggest that those at high fracture risk, particularly vertebral fracture, may benefit by continued treatment.

Low-dose zoledronate in osteopenic postmenopausal women: a randomized controlled trial

CONTEXT

Annual iv administration of 5 mg zoledronate decreases fracture risk. The skeletal effects of annual treatment with doses of zoledronate under 4 mg have not been assessed.

OBJECTIVE

Our objective was to determine the skeletal effects of single doses of zoledronate of 5 mg or less.

DESIGN, SETTING, AND PARTICIPANTS

This was a double-blind, randomized, placebo-controlled trial over 1 yr at an academic research center in 180 postmenopausal women with osteopenia.

INTERVENTION

Intervention was a single baseline administration of iv zoledronate in doses of 1, 2.5, or 5 mg, or placebo.

MAIN OUTCOME MEASURES

The primary endpoint was change in bone mineral density (BMD) at the lumbar spine. Secondary endpoints were change in BMD at the proximal femur and total body and changes in biochemical markers of bone turnover.

RESULTS

After 12 months, change in spine BMD was greater in each of the zoledronate groups than in the placebo group [mean (95% confidence interval) difference vs. placebo was 3.5% (2.2-4.8%) for 1 mg, 4.0% (2.7-5.3%) for 2.5 mg, and 3.6% (2.3-4.9%) for 5 mg zoledronate, P < 0.001 for each dose]. Change in BMD at the total hip was greater in each of the zoledronate groups than the placebo group [mean (95% confidence interval) difference vs. placebo was 2.7% (1.9-3.5%) for 1 mg, 3.6% (2.8-4.4%) for 2.5 mg, and 3.6% (2.8-4.4%) for 5 mg zoledronate, P < 0.001 for each dose]. Each of the bone turnover markers, β-C-terminal telopeptide of type I collagen and procollagen type I N-terminal propeptide, was lower by at least 40% in each of the zoledronate groups than the placebo group throughout the trial (P < 0.001 vs. placebo for each marker for each dose). There was evidence for a dose-dependent effect of zoledronate on each of the markers (P for trend <0.001).

CONCLUSION

Annual administration of doses of iv zoledronate lower than 5 mg produces substantial antiresorptive effects. Trials assessing the antifracture efficacy of low doses of zoledronate are justified.

Effect of zoledronic acid compared with raloxifene on bone turnover markers in postmenopausal women with low bone density

OBJECTIVE

The aim of this study was to assess the effects of zoledronic acid and raloxifene on bone turnover markers.

METHODS

This multicenter, randomized, double-blind study involved 110 postmenopausal women with low bone mineral density who received either a single intravenous infusion of zoledronic acid 5 mg or 6 months of daily oral raloxifene 60 mg. The primary efficacy variable was change from baseline in the bone resorption marker urine N-telopeptide of type I collagen. The secondary efficacy variable was change from baseline in the bone formation marker serum bone-specific alkaline phosphatase. Analysis time points were at 2, 4, and 6 (primary) months.

RESULTS

At 6 months, zoledronic acid produced a significantly greater reduction than did raloxifene in urine N-telopeptide of type I collagen (P < 0.001). Zoledronic acid also yielded significantly greater decreases in urine N-telopeptide of type I collagen at 2 and 4 months and in serum bone-specific alkaline phosphatase at all time points (P < 0.001 vs raloxifene for all comparisons). Both treatments were well tolerated. More adverse events occurred in the zoledronic acid group; these were primarily transient postdose symptoms that occurred within the first 3 days after the infusion.

CONCLUSIONS

Zoledronic acid demonstrated significantly greater decreases in bone turnover markers than did raloxifene in postmenopausal women with low bone mass.

Role of zoledronic acid in the prevention and treatment of osteoporosis

Taken once a year, intravenous zoledronic acid (Zol) (Reclast® or Aclasta®) is a third-generation nitrogen-containing bisphosphonate that is effective compared with placebo in reducing the risk of fractures in patients with postmenopausal osteoporosis and recent low-trauma hip fracture. In glucocorticoid-induced osteoporosis, there is no significant difference between Zol and risedronate for new fractures. Improvements in bone mineral density and early reduction of bone remodeling markers are observed in postmenopausal osteoporosis, recent low-trauma hip fracture, and glucocorticoid-induced osteoporosis. Given that Zol is generally well tolerated and very convenient, it is an interesting therapeutic option for aging patients who take multiple oral drugs, who have adherence or gastrointestinal tolerance issues, and who have an indication for oral bisphosphonates. Zol is not recommended for patients with severe renal impairment. Vitamin D deficiency should be corrected before the administration of Zol.

Osteoporosis update from the 2010 santa fe bone symposium

The 11th Santa Fe Bone Symposium was held in Santa Fe, NM, USA, on August 6-7, 2010. This annual event addresses clinically relevant advances in the fields of osteoporosis and metabolic bone disease. The venue includes plenary presentations by internationally recognized experts, oral presentations of abstracts, and interactive panel discussions of challenging cases and controversial issues. Attendees are active participants throughout the symposium program. Topics for the 2010 symposium included potential applications of novel technologies for the assessment of skeletal health for research and clinical practice; new and emerging treatments for osteoporosis; appropriate use of pharmacological agents to prevent osteoporosis; controversies with bisphosphonate therapy; practical applications of the World Health Organization fracture risk assessment tool (FRAX; World Health Organization Collaborating Centre for Metabolic Bone Diseases, University of Sheffield, UK); insights into the use of osteoanabolic agents to enhance fracture healing; and challenges in laboratory testing in the assessment of factors contributing to skeletal fragility. Concurrent sessions focused on critical thinking for technologists in the acquisition and analysis of data with dual-energy X-ray absorptiometry. The key messages from each presentation, including the best available medical evidence and potential current and future clinical applications, are provided here.

Diagnosis and treatment of osteopenia

Osteopenia is a term to define bone density that is not normal but also not as low as osteoporosis. By definition from the World Health Organization osteopenia is defined by bone densitometry as a T score -1 to -2.5. There are many causes for osteopenia including calcium and vitamin D deficiency and inactivity. Genetics plays an important role in a person's bone mineral density and often Caucasian women with a thin body habitus who are premenopausal are found to have osteopenia. Correction of calcium and vitamin D deficiency and walking 3 to 5 miles a week can often improve bone density in the hip and spine. There are a variety of pharmaceutical agents that have been recommended for the treatment of osteopenia and osteoporosis including hormone replacement therapy, selective estrogen receptor modulator therapy, anti-resorptive therapy. In addition patients with osteoporosis who have failed anti-resorptive therapy can have a significant improvement in their bone density with anabolic therapy.

Zoledronic acid: clinical utility and patient considerations in osteoporosis and low bone mass

The availability of a once-a-year zoledronic acid infusion heralds a new era in the management of osteoporosis. It virtually eliminates the problem of poor compliance with orally administered bisphosphonates and, because it bypasses the gastrointestinal tract, it is not associated with gastrointestinal side effects. Zoledronic acid is effective for the treatment and prevention of postmenopausal osteoporosis, and for the treatment of osteoporosis in men, and glucocorticoid-induced osteoporosis. When administered within three months of a hip fracture, it reduces mortality and the risk of subsequent fractures. It is remarkably free of serious adverse effects. After administration of the intravenous infusion, about 18% of bisphosphonate-naïve patients experience an acute-phase reaction, including low-grade temperature, aches, and pains. This is reduced to about 9% in those who have been treated with oral bisphosphonates, and is further reduced by the concomitant and subsequent administration of acetaminophen. The likelihood and magnitude of the acute-phase reaction is less after the second infusion. Other adverse effects are similar to those encountered with other bisphosphonates. Because it is mostly excreted by the kidneys, zoledronic acid should not be administered to patients with a creatinine clearance less than 35 mL/min. It should not be administered to patients with hypocalcemia.

Zoledronic acid infusion for prevention and treatment of osteoporosis

Osteoporotic fractures are associated with significant morbidity, reduced quality of life, increased mortality, and high health care costs. Bisphosphonates are standard therapy for treatment of osteoporosis. However, patient compliance and persistence with oral weekly or monthly bisphosphonate therapy are suboptimal and may lead to reduced effectiveness. Zoledronic acid (ZOL) is an intravenous bisphosphonate that is given once yearly for the treatment of osteoporosis via a medically supervised 15-minute infusion. This ensures compliance for a full 12 months. In clinical trials, an annual infusion of ZOL 5 mg has shown sustained efficacy in reducing hip and spine fractures in postmenopausal women with osteoporosis. It has also been shown to increase bone density in postmenopausal women with osteopenia (low bone mass) and in men with osteoporosis. Transient flu-like symptoms are the most common adverse effects following ZOL infusion, and these can generally be managed with acetaminophen. The availability of an intravenous bisphosphonate that ensures compliance over a long dosing interval may help to overcome barriers to efficacy resulting from poor long-term compliance with oral agents.

Prolonged antiresorptive activity of zoledronate: a randomized, controlled trial

Annual intravenous administration of 5 mg of zoledronate decreases fracture risk over 3 years. The optimal dosing interval of 5 mg of zoledronate is not known. In order to determine the duration of the antiresorptive action of a single 5-mg dose of intravenous zoledronate, we conducted a 3-year double-blind, randomized, placebo-controlled trial in a volunteer sample of 50 postmenopausal women with osteopenia. The coprimary endpoints were the bone turnover markers β-C-terminal telopeptide of type I collagen (β-CTX) and serum procollagen type-I N-terminal propeptide (P1NP). Secondary endpoints were bone mineral density (BMD) at the lumbar spine, total hip, and total body. After 3 years, mean (95% confidence interval) levels of serum β-CTX and P1NP were 44% (27-60) and 40% (24%-56%) lower in the zoledronate group (p < .001 versus placebo for each marker). BMD was higher in the zoledronate group than in the placebo group by an average of 6.8% (4.6%-9.1%) at the lumbar spine, 4.0% (1.8%-6.3%) at the total hip, and 2.0% (0.9%-3.0%) at the total body (p < .001 for each skeletal site). Between-group differences in markers of bone turnover and BMD were stable from 12 to 36 months. These data demonstrate that the antiresorptive effects of a single 5-mg dose of zoledronate are sustained for 3 years; clinical trials to investigate the antifracture efficacy of dosing intervals longer than 1 year are justified.

Update on the use of zoledronic acid in the management of osteoporosis

Zoledronic acid is a third-generation bisphosphonate that is administered as an annual infusion, and it has some interesting features. After a successful preclinical development program, it has undergone extensive testing in postmenopausal osteoporosis where it has substantial antifracture efficacy at the vertebral, nonvertebral, and hip sites. It has been shown to be effective in reducing vertebral and nonvertebral fractures in patients who had recently suffered a femoral neck fracture, and has demonstrated efficacy in preventing and reversing bone loss in glucocorticoid osteoporosis. The drug is generally well tolerated, although it has been shown to cause significant acute phase reactions occurring in the first 3 days, mainly after the first infusion. Care must be taken to avoid using the drug in those with significantly impaired renal function, although initial concerns about a relationship to atrial fibrillation and osteonecrosis of the jaw have so far proved to be unfounded.

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

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

Development of clinical utility of zoledronic acid and patient considerations in the treatment of osteoporosis

Osteoporosis is a major health concern, which results in the increased risk of fractures. There is a high risk for the first or consecutive fractures leading to considerable morbidity and debilitating consequences if osteoporosis is untreated. Currently, bisphosphonates are the mainstay of treatment for osteoporosis though long-term persistence and adherence to bisphosphonates, especially those taken orally, remain low. This medication noncompliance has serious consequences on osteoporotic patients as it is associated with a significantly higher fracture risk. Intravenous (IV) zoledronic acid (ZOL), developed to increase compliance by overcoming the frequent and burdensome dosing requirements of oral bisphosphonates, is the first and the only once-yearly bisphosphonate globally approved for use in the treatment of up to 6 indications of osteoporosis. Several clinical studies have documented that a single infusion of IV ZOL resulted in decreased bone turnover and improved bone density for at least 12 months post infusion. This article traces the development of ZOL's clinical utility and evaluates its patient preference by collating data from all major clinical trials, studying the efficacy and safety of ZOL in the treatment of osteoporosis and other benign bone disorders.

The role of zoledronic acid in the management of osteoporosis

Bisphosphonates are the current standard of care for treatment of osteoporosis. However, oral bisphosphonates are associated with complicated dosing regimens because of poor absorption and have the potential for upper gastrointestinal (GI) tract irritation, resulting in poor adherence and persistence. Zoledronic acid (ZOL) 5 mg, a once-yearly intravenous bisphosphonate, is approved for treatment and prevention of postmenopausal osteoporosis, increasing bone mass in men with osteoporosis, and treatment and prevention of glucocorticoid-induced osteoporosis. Because it is administered as an infusion, ZOL ensures adherence and persistence over the entire 12-month dosing interval and bypasses the GI absorption/irritation problems associated with oral bisphosphonates. The objective of this study was to review the safety and efficacy of 5 mg ZOL and its potential for improving patient compliance. Published reports dating back to 2001 were reviewed, with emphasis on osteoporosis treatment. In the HORIZON-Pivotal Fracture Trial, annual infusions of 5 mg ZOL produced significant reductions in risk of morphometric vertebral fractures (70%) and hip fractures (41%) vs placebo over 3 years in postmenopausal women with osteoporosis. In the HORIZON-Recurrent Fracture Trial, an annual infusion of 5 mg ZOL after repair of a recent low-trauma hip fracture was associated with significant reductions in risk for new clinical fractures (35%) vs placebo. In men with osteoporosis, an annual treatment of ZOL over 2 years increased lumbar spine bone mineral density (BMD) by 6% compared with baseline. In patients starting or continuing treatment with chronic glucocorticoids, ZOL resulted in significantly greater increases in lumbar spine BMD over 1 year than an oral bisphosphonate. In postmenopausal women with osteopenia, a single infusion of ZOL over a 2-year period produced significantly greater gains in lumbar spine and hip BMD than placebo. ZOL is generally safe and well tolerated. Five milligrams of ZOL has the potential to improve compliance with osteoporosis therapy and, consequently, to reduce fracture risk in clinical practice.