Continuous and cyclical clodronate therapies and bone density in postmenopausal bone loss

Clodronate

Two early observations about the first generation bisphosphonate, clodronate, suggested that it would likely have clinical utility; specifically, it was a more potent anti-resorptive but a less potent inhibitor of mineralisation than its predecessor etidronate. The known mechanism of action differs from that of the later nitrogen-containing bisphosphonates, as clodronate is metabolised intracellularly to a toxic analog of adenosine triphosphate, AppCCl2p, which causes mitochondrial dysfunction, impaired cellular energy metabolism and osteoclast apoptosis. For pre-clinical studies in a variety of disease models, liposomal clodronate has become the agent of choice for macrophage depletion, for example in a recent study to enhance haematopoietic chimerism and donor-specific skin allograft tolerance in a mouse model. For clinical use, clodronate was developed in oral and injectable formulations; while poorly absorbed from the gastro-intestinal tract, its absorption at 1-3% of the administered dose is approximately three-fold higher than for nitrogen-containing bisphosphonates. Following an early setback due to an erroneous association with toxic adverse events, a number of successful clinical studies have established clodronate, predominantly in its oral formulations, as a highly successful treatment in Paget's disease, hypercalcaemia (benign and malignant), multiple myeloma, and early or metastatic breast cancer. Novel uses in other disease areas, including veterinary use, continue to be explored.

Clodronate: new directions of use

Clodronate is the father of bisphosphonates. For over three decades it has been subject of study in biological and clinical areas, proving to be an extremely interesting molecule from different points of view. It has been the first drug for osteoporosis that can be administered pulsatorily (once every 15 days or once a week). This, along with good tolerability, has been the first cause of its success, when there were no solid data in literature about its antifracture efficacy. There are three published studies that prove its antifracture effect: two by McCloskey published in 2004 and 2007 on BMR, and our study about fracture prevention in corticosteroids OP. In these studies a dose of 800 mg/day orally administered or 100 mg/week I.M. was used, and they are basically the same if you consider that clodronate absorption, orally administered, is on average 1.9%. However, a series of works where higher doses were used (1600 mg orally administered) with greater effectiveness on bone mass, especially in higher risk populations, lead us to consider the use of 200 mg i.m. formulation. First of all, we proved densitometric equivalence of 200 mg i.m./14 days and 100 mg i.m./week in a first study; then, in a second study, we proved a greater densitometric efficacy of 200 mg/week compared to 100 mg/week, clearer at femoral level, where the drug had not proven to prevent femoral fracture because of inadequate bone mass increase at that level. Moreover, as for ibandronate case, monthly dose was doubled compared to pivotal trial, in order to maximize the effects on femoral bone mass and therefore prevent femoral fractures. Consequently, on the basis of the risk envelope, whether it is identified according to BMD and the presence of one risk factor at least or more correctly identified through risk chart (FRAX or DeFRA), you can put forward a differential use of 100 mg i.m. and 200 mg i.m., weekly, "off-label" or every 14 days, adjusting doses in relation to fracture risk and painful symptoms gravity, as well as improving its ease of use and therefore assist compliance. Common experience and clinical and biological works have proved that clodronate has an analgesic effect that can be increased by doubling the doses. The analgesic effect is present not only with patients with fractures, but also with patients suffering from osteoarthritis or arthritis. Therefore, the drug would fit well in the therapeutic program of rheumatic patient, also because of its symptomatic effects. Clodronate at small doses (2 mg) could also have protective effects on cartilage (introduction of intra-articular formulation is expected) and at 10-100 fold higher doses it has certainly anti-inflammatory effects and more specifically antimacrophage and anticytokine effects (IL-1, IL-6, TNFalpha, PGE). These effects are amplified by putting clodronate in monolayer liposomes. This drug, therefore, has to be considered as adjuvant in arthritis therapy, whose origin can be linked to a strong osteoclastic activation caused by an increase of cytokines and the RANKL/OPG relationship. It is clear that clodronate can work on cytokine at first and on osteoclastic effector in the end. The drug has been used "off-label" for decades intravenously in complex regional pain syndrome (CRPS type 1) in relation to schemes that change according to different Authors and according to cumulative doses ranging from 3 to 5 g. The introduction on the market of the 200 mg i.m. formulation could allow to get more practical but equally effective schemes. For example, we used this scheme: 200 mg/day for 10 days and then 200 mg every other day for 20 days (cumulative dose of 4 g in a month). Said scheme can be repeated in the following months in particular cases. Results, as for efficacy and lack of relapses, show that clodronate is the leader drug for this syndrome. In recent years, relationship between costs and benefits has started to matter, especially after the creation of some algorithms, such as FRAX, that let us choose patients with a higher fracture risk in 10 years, and after pharmaceutic-economic models that let us calculate FRAX intervention threshold, on the basis of drug price and monitoring, antifracture efficacy, quality of life and how much a community can or wants to spend. In this respect, a sub-analysis of McCloskey's study on people over the age of 75, conducted on 3974 subjects, shows that clodronate is more efficient with patients with a higher fracture risk, calculated according to FRAX. Furthermore, another study by McCloskey revealed that, for a 100-pound/year drug (very similar to clodronate), 'cost effective' intervention threshold is about 7-10%. In conclusion, clodronate prevents fractures, decrease osteo-articular pain, is easy to handle, tolerable and had a great cost/benefit relationship.

Effects of two administration schemes of intramuscular clodronic acid on bone mineral density: a randomized, open-label, parallel-group study

BACKGROUND

Clodronic acid is a bisphosphonate used in the prevention and treatment of postmenopausal bone loss. Previous evidence suggests a direct dose-response relationship for the densitometric effect of clodronic acid. Therefore, as it is widely accepted that a reduction in the dosing frequency of bisphosphonates may improve adherence and therefore therapeutic outcomes, an increase in the interval between consecutive administrations of clodronic acid might be associated with a concomitant increase in the overall bisphosphonate dose received. However, to our knowledge, a direct comparison of the effects of intramuscular clodronic acid 100 mg once weekly with a regimen consisting of a higher dose and a longer interval between two consecutive administrations is still lacking.

OBJECTIVE

This study compared the increase in bone mineral density (BMD) achieved with two different administration schemes of intramuscular clodronic acid (100 mg once weekly and 200 mg every 2 weeks) in patients with postmenopausal osteoporosis.

STUDY DESIGN AND SETTING

This randomized, open-label, parallel-group trial was conducted in the Osteoporosis and Instrumental Diagnosis Center 'OsteoArticolar' (University of Siena, Siena, Italy) between January 2007 and December 2009.

PATIENTS

Consecutive women aged 50-80 years with postmenopausal osteoporosis, diagnosed ≥5 years prior to inclusion in the study, were eligible for participation in this study.

INTERVENTION

Patients were randomized to receive either intramuscular clodronic acid (Clasteon®) 100 mg (group A) + lidocaine (lignocaine) once weekly or intramuscular clodronic acid 100 mg + lidocaine for two consecutive days every 2 weeks (group B), for 2 years.

RESULTS

In total, 30 patients were randomized to group A and 30 patients to group B. Significant increases in mean ± SD BMD of the lumbar spine versus baseline values were observed in both groups at 1 and 2 year(s) from treatment initiation (group A - year 1: +2.8% ± 1.7%, p < 0.05; year 2: +3.5% ± 2.2%, p < 0.01; group B - year 1: +2.7% ± 2.1%, p < 0.05; year 2: +3.9% ± 2.2%, p < 0.01). Mean ± SD BMD at the femoral neck also significantly increased versus baseline in group A at both timepoints (year 1: +2.3% ± 1.9%, p < 0.05; year 2: +2.5% ± 1.9%, p < 0.05), while the increase reported in group B was significant only after 2 years of treatment (year 1: +1.9% ± 2.2%; year 2: +2.8% ± 1.8%; p < 0.05). Significant mean ± SD increases in total femur BMD were observed only in group A at 2 years (+2.4% ± 1.9, p < 0.05). No differences between study groups were reported. Two non-traumatic vertebral fractures were observed in group A (6.6%) and three in group B (10.0%). Treatment was well tolerated; mild pain at injection site was observed in three patients (one in group A, 3.3%; two in group B, 6.6%).

CONCLUSION

This randomized study suggests, for the first time to the author's knowledge, a similar effect of intramuscular clodronic acid 100 mg once weekly and 200 mg every 2 weeks (two 100 mg administrations on two consecutive days) on BMD in women with postmenopausal osteoporosis. The administration of intramuscular clodronic acid 200 mg every 2 weeks may therefore represent a new therapeutic option in the treatment of postmenopausal osteoporosis.

Clodronic acid formulations available in Europe and their use in osteoporosis: a review

Clodronic acid (Cl(2)-MBP [dichloromethylene bisphosphonic acid], clodronate) is a halogenated non-nitrogen-containing bisphosphonate with antiresorptive efficacy in a variety of diseases associated with excessive bone resorption. The drug is believed to inhibit bone resorption through induction of osteoclast apoptosis, but appears also to possess anti-inflammatory and analgesic properties that contrast with the acute-phase and inflammatory effects seen with nitrogen-containing bisphosphonates. Clodronic acid has been shown to be effective in the maintenance or improvement of bone mineral density when given orally, intramuscularly or intravenously in patients with osteoporosis. Use of the drug is also associated with reductions in fracture risk. The intramuscular formulation, which is given at a dose of 100 mg weekly or biweekly, is at least as effective as daily oral therapy and appears more effective than intermittent intravenous treatment. Intramuscular clodronic acid in particular has also been associated with improvements in back pain. The drug is well tolerated, with no deleterious effects on bone mineralization, and use of parenteral therapy eliminates the risk of gastrointestinal adverse effects that may be seen in patients receiving bisphosphonate therapy.

Unexpected degradation of the bisphosphonate P-C-P bridge under mild conditions

Unexpected degradation of the P-C-P bridge from novel bisphosphonate derivative 1a and known etidronate trimethyl ester (1b) has been observed under mild reaction conditions. A proposed reaction mechanism for the unexpected degradation of 1a and 1b is also reported.

Clodronic acid in the treatment of postmenopausal osteoporosis

BACKGROUND

Clodronic acid, a first-generation bisphosphonate, has been successfully used in the treatment of high bone turnover states, Paget's disease and osteolytic bone metastases. However, controversies remain over its optimal dosage and method of administration in the treatment of postmenopausal osteoporosis. In this study we aimed to evaluate the effect of clodronic acid treatment for 3 years on bone mineral density (BMD) in women with postmenopausal osteoporosis.

METHODS

This was a prospective, open-label, randomised, controlled study that was conducted in an outpatient clinic at the Bone Metabolism Unit of a tertiary referral centre university hospital. Thirty postmenopausal women (age range 48-73 years) with osteoporosis and a control group of 49 osteoporotic women (age range 47-74 years) received randomised therapy. The clodronic acid group of participants received oral doses of clodronic acid 800 mg plus elemental calcium 500 mg and 400 IU of vitamin D daily, while the control group was treated with calcium and vitamin D only. BMD was measured by dual energy x-ray absorptiometry at yearly intervals. Biochemical markers of bone turnover were also measured.

RESULTS

In this clinical study of postmenopausal women with osteoporosis, 36 months of clodronic acid treatment significantly increased average femoral neck BMD by 3.2 +/- 2.9%, trochanter BMD by 2.2 +/- 2.9% and lumbar spine BMD by 3.1 +/- 3%. In the control group, femoral neck, trochanter and lumbar spine BMD decreased by -6 +/- 2.7%, -7.3 +/- 2.5% and -5.4 +/- 2%, respectively (p<0.01, p<0.05 and p<0.05 for clodronic acid vs control, respectively). There was a significant decrease in urinary hydroxyproline (-38.3%) over 3 years in the clodronic acid group compared with baseline (p<0.05), while no significant change occurred in the control group. Clodronic acid was well tolerated and compliance was good. There were no clinically meaningful differences in the incidence of individual adverse events between the groups.

CONCLUSION

These results indicate that daily oral administration of clodronic acid 800 mg provides benefits to skeletal bone density in osteoporotic postmenopausal women. Calcium and vitamin D supplementation alone did not prevent further bone loss.

Calcium from LactoCalcium milk mineral after digestion with pepsin stimulates mineralized bone nodule formation in human osteoblast-like SaOS-2 cells in vitro and may be rendered bioavailable in vivo

Many individuals cannot obtain the optimum calcium requirement from food for a variety of reasons. Therefore, calcium supplements are important sources of dietary calcium. One of the calcium sources commercially available is LactoCalcium (milk minerals) that has 28% calcium, and a 2:1 ratio of calcium to phosphorus. The objectives of this study were (a) to examine whether calcium can be released from LactoCalcium by using digestive enzymes and (b) to determine its biological activity by examining its ability to stimulate bone formation. LactoCalcium was treated in vitro by using simulated gastric and intestinal fluids or porcine gastric, pancreatic and intestinal extracts. Our results indicate the role of enzymes or bile extract in the digestion of the product. We show that, by increasing the concentration of pepsin at a fixed concentration of LactoCalcium (substrate), the percentage of released calcium increased in a dose-dependent manner, showing that, at the right enzyme concentration, as much as 100% of the calcium present in LactoCalcium can be made available. The biological activity of the digested calcium was demonstrated by the stimulation of mineralized bone nodules in SaOS-2 cells in a dose-dependent manner. Thus, 1 mM and 3 mM calcium released from LactoCalcium increased the nodule area by 23.17 mm(2) (p<0.0001) and 77.78 mm(2) (p<0.0001), respectively, as compared to a value of 0.99 mm(2) at 0.5 mM calcium from LactoCalcium. These results demonstrate the in vitro bioavailability and bioactivity of calcium from LactoCalcium and serve as a basis for carrying out in vivo analyses to determine the suitability of using LactoCalcium as a source of calcium for individuals at risk of developing osteoporosis.

Synthesis of novel (1-alkanoyloxy-4-alkanoylaminobutylidene)-1,1-bisphosphonic acid derivatives

A novel strategy for the synthesis of (1-alkanoyloxy-4-alkanoylaminobutylidene)-1,1-bisphosphonic acid derivatives (1a-d) via (1-hydroxy-4-alkanoylaminobutylidene)-1,1-bisphosphonic acid derivatives (2a-d), starting from alendronate has been developed with reasonable 51–77% overall yields. Intermediate products, (1-hydroxy-4-alkanoylaminobutylidene)-1,1-bisphosphonic acid derivatives (2a-d), were prepared in water with reasonable to high yields (52–94%).

Secondary hyperparathyroidism is associated with vitamin D receptor polymorphism and bone density after renal transplantation

Immunosuppresive treatment and secondary hyperparathyroidism (SHPT) are considered among the most important pathogenetic factors for post-renal transplant bone disease. The aim of this study was to investigate the relationships among vitamin D receptor (VDR) gene polymorphism, parathyroid hormone (PTH) levels and bone density in renal transplant recipients. We enrolled 75 patients (50 male and 25 female, mean age 47+/-11 years) who had undergone kidney transplantation 53+/-4 months before. All patients underwent an evaluation of the main biochemical parameters of bone metabolism as well bone densitometry. VDR alleles were typed by a PCR assay based on a polymorphic BsmI restriction site. When patients were categorized according to the VDR genotype (BB, Bb, bb), serum creatinine and the cumulative doses of immunosuppressive drugs were similar across the groups. PTH levels higher than 80 pg/ml were found in 53.6% of the patients, with the highest values being detected in the bb VDR genotype (P<0.05). PTH was significantly correlated to urinary NTx values. Bone density was low in the whole population; however, spinal bone density was lower in the bb subgroup (P<0.02). In the whole population, only PTH (P<0.05) and body mass index (P<0.01) were independent predictors of spinal bone density. Grouping patients by the VDR gene polymorphism, only PTH continued to be an independent predictor of spinal bone density in the bb allele subgroup (R(2) Adj.=0.17). We can conclude that the VDR genotype polymorphism affects bone density of renal transplant recipients via its effects on the severity of SHPT.

Clodronate reduces vertebral fracture risk in women with postmenopausal or secondary osteoporosis: results of a double-blind, placebo-controlled 3-year study

The efficacy of oral clodronate 800 mg daily to reduce vertebral fractures was studied in 593 women with postmenopausal or secondary osteoporosis. The incidence of vertebral fractures was significantly reduced by 46%. The effect was not modified by the underlying cause of osteoporosis or other baseline factors including bone mineral density, QUS, weight, and smoking.

INTRODUCTION

This study aimed to determine if the bisphosphonate, clodronate (Bonefos), reduced the incidence of vertebral fractures in osteoporotic women.

MATERIALS AND METHODS

Women fulfilling the WHO criteria for osteoporosis at the lumbar spine (T-score </= -2.5) and/or with at least one prevalent vertebral fracture were recruited to a 3-year double-blind, placebo-controlled study. A total of 593 patients were randomized to two strata comprised of women with postmenopausal osteoporosis (I, n = 483) and secondary osteoporosis (II, n = 110). They received either clodronate 800 mg daily orally (n = 292) or an identical placebo (n = 301). All patients received a calcium supplement of 500 mg daily. BMD was measured at 6, 12, 24, and 36 months, and lateral spine radiographs were obtained at baseline and annually thereafter for vertebral morphometry.

RESULTS

Treatment with clodronate was associated with a significant increase in mean spine BMD over 3 years (percent change from baseline, 4.35 +/- 6.34% versus 0.64 +/- 6.02% in the placebo group, p < 0.0001). At the hip, clodronate maintained total BMD, whereas a significant decrease was observed in the placebo group (percent change from baseline 0.70 +/- 5.67% versus -3.03 +/- 6.32% in the placebo group, p < 0.0001). The changes at the spine and hip were similar in both strata. Incident vertebral fractures at 3 years were observed in 63 women in the placebo group and 33 patients receiving clodronate (relative risk, 0.54; 95% CI, 0.37-0.80; p = 0.001). Clodronate significantly reduced vertebral fracture risk in both strata and in women with or without prior vertebral fracture at baseline. Nonvertebral osteoporosis-associated fractures occurred in 21 women in the placebo group and in 14 women treated with clodronate. Treatment was well tolerated, with no significant difference in adverse event rates, including esophagitis, during clodronate treatment.

CONCLUSION

We conclude that clodronate 800 mg daily is a safe and effective treatment to reduce fracture risk in women with osteoporosis, regardless of causation.

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.

First synthesis of etidronate partial amides starting from PCl3

Methods for the preparation of mixed tetra-amide esters 1 and 2, the partial amide ester 3, and tri- and P,P-diamides 4 and 5 from monophosphorus spieces 12, 8 and 9, respectively, were developed. Compounds 8 and 9 were obtained from phosphorus trichloride via MeOPCl2, which was treated with 2 eq. and 4 eq. of piperidine, followed by water or acetyl chloride, respectively. Tetrasubstituted amide bisphosphonates 1 and 2 were selectively dealkylated with lithium or silyl halide to achieve target compounds 3-5. Piperidine was found to be a good desilylation reagent. Quantum mechanical calculations illustrate why derivative 2 was produced in low yield. The usefulness of compounds 1, 3 and 4 as prodrugs of etidronate was determined in aqueous buffer and human serum.

Clodronate: mechanisms of action on bone remodelling and clinical use in osteometabolic disorders

Clodronate (CI2MBP) is a non-aminated bisphosphonate that inhibits bone resorption. Studies on the mechanisms of action of this molecule on bone metabolism have been limited and only recently has information on the molecular machinery that underlies its effects on the bone remodelling process become available. Pharmacological and clinical studies have demonstrated the effectiveness of clodronate in the treatment of postmenopausal osteoporosis and in all conditions of excessive bone resorption, such as Paget's disease, hypercalcaemia of malignancy and osteolytic metastases. Clodronate is the only bisphosphonate currently available on the market for both oral and parenteral administration. Treatment with clodronate via intramuscular administration of doses of 100 mg/week has shown significant effects on bone mineral density after 6 months in patients with postmenopausal osteoporosis and these effects are maintained 3 years after the start of the treatment. In a recent controlled clinical study, a significant increase in bone mineral density was observed, associated with a 46% reduction in the incidence of vertebral fractures. However, most relevant studies have been small, unblinded and short-term and have not systematically examined the effects of the dose and dosing intervals on bone mineral density and markers of bone turnover. Ongoing controlled clinical studies may offer answers regarding potential use of clodronate in osteoporosis and also about dosage of intermittent administration. This review summarises the accumulated knowledge in the mechanisms of action of clodronate on bone remodelling. Moreover, the clinical trials on the use of clodronate in metabolic bone diseases are described in-depth. We believe that this work will help to better focus on the need for more research on a compound which has potential applications in prevention and therapy of osteoporosis. However, studies that demonstrate an effect on the rate of fractures are needed before any recommendation can be made.

The effects of vitamin D receptor polymorphism on secondary hyperparathyroidism and bone density after renal transplantation

Immunosuppresive treatment and secondary hyperparathyroidism (SHPT) are considered among the most important pathogenetic factors for postrenal transplant bone disease. The aim of this study was to investigate the relationships among vitamin D receptor (VDR) gene polymorphism, parathyroid hormone (PTH) levels, and bone density in renal transplant recipients. We enrolled 69 patients (47 men and 22 women; mean age, 47 +/- 11 years) who had undergone kidney transplantation 51 +/- 5 months before. All patients underwent an evaluation of the main biochemical parameters of bone metabolism as well as bone densitometry. VDR alleles were typed by a polymerase chain reaction (PCR) assay based on a polymorphic BsmI restriction site. When the patients were categorized according to the VDR genotype (BB, Bb, and bb), serum creatinine, and the cumulative doses of immunosuppressive drugs were similar across the groups. PTH levels higher than 80 pg/ml were found in 53.6% of the patients, with the highest values being detected in the bb VDR genotype (p < 0.05). PTH was significantly correlated to urinary type I collagen cross-linked N-telopeptide (NTx) values. Bone density was low in the whole population; however, spinal bone density was lower in the bb subgroup (p < 0.02). In the whole population, only PTH (p < 0.05) and body mass index (BMI; p < 0.01) were independent predictors of spinal bone density. When grouping the patients by the VDR gene polymorphism, only PTH continued to be an independent predictor of spinal bone density in the bb allele subgroup (R2 adj. = 0.17). We can conclude that the VDR genotype polymorphism affects bone density of renal transplant recipients via its effects on the severity of SHPT.

Effect of cyclical intravenous clodronate therapy on bone mineral density and markers of bone turnover in patients receiving home parenteral nutrition

BACKGROUND

Patients receiving home parenteral nutrition (HPN) because of intestinal failure are at high risk of developing osteoporosis.

OBJECTIVE

We studied the effect of the bisphosphonate clodronate on bone mineral density (BMD) and markers of bone turnover in HPN patients.

DESIGN

A 12-mo, double-blind, randomized, placebo-controlled trial was conducted to study the effect of 1500 mg clodronate, given intravenously every 3 mo for 1 y, in 20 HPN patients with a bone mass T score of the hip or lumbar spine of less than -1. The main outcome measure was the difference in the mean percentage change in the BMD of the lumbar spine measured by dual-energy X-ray absorptiometry. Secondary outcome measures included changes in the BMD of the hip, forearm, and total body and biochemical markers of bone turnover, ie, serum osteocalcin, urinary pyridinoline, and urinary deoxypyridinoline.

RESULTS

The mean (+/-SEM) BMD of the lumbar spine increased by 0.8 +/- 2.0% in the clodronate group and decreased by 1.6 +/- 2.0% in the placebo group (P = 0.43). At all secondary skeletal sites (ie, hip, total body, and distal forearm), we observed no changes or small increases in the BMD of the clodronate group and decreases in the BMD of the placebo group. In the clodronate group, biochemical markers of bone resorption decreased significantly (P < 0.05).

CONCLUSIONS

Clodronate significantly inhibits bone resorption as assessed by changes in biochemical markers of bone turnover. Although the mean BMD increased in the clodronate group, cyclic clodronate therapy failed to increase spinal BMD significantly at 12 mo.

Pharmacokinetic and pharmacodynamic evaluation of intermittent versus continuous alendronate administration in rats

We studied the differences in pharmacokinetics and pharmacodynamics of the same dose of alendronate administered subcutaneously as intermittent bolus injection or continuous infusion in rats. Two rat models of bone disease were applied. Bone cancer was produced by intratibial inoculation of Walker carcinosarcoma cells, and a model of augmented bone resorption was produced by vitamin D(3) treatment of rats that had undergone thyroidparathyroidectomy. Higher amounts of alendronate were found in bones and in internal organs after bolus drug administration as compared with continuous infusion. Drug effects on plasma calcium levels and on urine calcium excretion were similar in both modes of alendronate administration. Results of the study indicate that the pharmacokinetics (disposition) of alendronate is administration-dependent. The total amount found in bone does not directly represent the amount of alendronate that is pharmacologically active at the site of action in the bone and that affects bone remodeling. The findings suggest that there is no pharmacodynamic advantage for continuous infusion of alendronate. It is concluded that the preferred mode of administration should be selected according to secondary clinical criteria (like incidence of adverse effects and convenience of administration).

Alendronate prevents further bone loss in renal transplant recipients

The aim of this study was to investigate the effects of alendronate, calcitriol, and calcium in bone loss after kidney transplantation. We enrolled 40 patients (27 men and 13 women, aged 44.2 +/- 11.6 years) who had received renal allograft at least 6 months before (time since transplant, 61.2 +/- 44.6 months). At baseline, parathyroid hormone (PTH) was elevated in 53% of the patients and the Z scores for bone alkaline phosphatase (b-ALP) and urinary type I collagen cross-linked N-telopeptide (u-NTX) were higher than expected (p < 0.001). T scores for the lumbar spine (-2.4 +/- 1.0), total femur (-2.0 +/- 0.7), and femoral neck (-2.2 +/- 0.6) were reduced (p < 0.001). After the first observation, patients were advised to adhere to a diet containing 980 mg of calcium daily and their clinical, biochemical, and densitometric parameters were reassessed 1 year later. During this period, bone density decreased at the spine (-2.6 +/- 5.7%;p < 0.01), total femur (-1.4 +/- 4.2%; p < 0.05), and femoral neck (-2.0 +/- 3.0%; p < 0.001). Then, the patients were randomized into two groups: (1) group A-10 mg/day of alendronate, 0.50 microg/day of calcitriol, and 500 mg/day of calcium carbonate; and (2) group B-0.50 microg/day of calcitriol and 500 mg/day of calcium carbonate. A further metabolic and densitometric reevaluation was performed after the 12-month treatment period. At the randomization time, group A and group B patients did not differ as to the main demographic and clinical variables. After treatment, bone turnover markers showed a nonsignificant fall in group B patients, while both b-ALP and u-NTX decreased significantly in alendronate-treated patients. Bone density of the spine (+5.0 +/- 4.4%), femoral neck (+4.5 +/- 4.9%), and total femur (+3.9 +/- 2.8%) increased significantly only in the alendronate-treated patients. However, no trend toward further bone loss was noticed in calcitriol and calcium only treated subjects. No drug-related major adverse effect was recorded in the two groups. We conclude that renal transplanted patients continue to loose bone even in the long-term after the graft. Alendronate normalizes bone turnover and increases bone density. The association of calcitriol to this therapy seems to be advantageous for better controlling the complex abnormalities of skeletal metabolism encountered in these subjects.

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.

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

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

Bisphosphonate prodrugs: synthesis and in vitro evaluation of novel clodronic acid dianhydrides as bioreversible prodrugs of clodronate

P,P'-Diacetyl, P,P'-dibutyroyl, P,P'-dipivaloyl, and P,P'-dibenzoyl (dichloromethylene)bisphosphonic acid dianhydride disodium salts (2a-d) were synthesized and evaluated as novel bioreversible prodrugs of clodronate. The anhydrides were prepared by reacting anhydrous tetrasodium clodronate with a large excess of the corresponding acid anhydride. The dianhydrides 2a-d alone were more lipophilic than the parent clodronate, as determined by drug partitioning between 1-octanol and phosphate buffer at pH 7.4. They also were stable toward chemical hydrolysis in aqueous solutions (pH 7.4 and 2.0). The half-lives for chemical degradation in a buffer solution at 37 degrees C varied from 0.7 to 286 h and from 15 to 790 h at pH 2.0 and 7.4, respectively. The dianhydrides 2a,b,d underwent complete enzymatic hydrolysis to clodronate in 80% serum at 37 degrees C after 1 min, although 2c had a half-life of 3.3 h. The aqueous solubility of clodronate decreased considerably in the presence of Ca2+ ions. This is most probably due to formation of poorly water-soluble chelates, which may also hinder the oral absorption of clodronate. However, Ca2+ ions did not have an effect on the aqueous solubility of clodronic acid dianhydrides, and therefore, these prodrugs may improve oral absorption of the parent drug. In conclusion, these novel dianhydride derivatives may be potentially useful prodrugs of clodronate which, due to their lipophilicity and lack of Ca2+ chelating, increase its bioavailability after oral administration.

Intramuscular clodronate therapy in postmenopausal osteoporosis

Long-term daily administration of oral bisphosphonates has been effective in the treatment of postmenopausal osteoporosis, but the duration, mode and cost of the therapy may sometimes affect patient compliance. In Italy, the bisphosphonate clodronate is also available via the intramuscular (i.m.) route of administration, and the present study was performed to test its efficacy in postmenopausal osteoporosis. Ninety osteoporotic postmenopausal women were enrolled in a randomized, controlled 3 year study. The diet of all patients was adjusted to provide 1200-1300 mg of calcium daily, eventually by administration of supplements. Patients were randomly assigned to no therapy (30 patients) or to receive clodronate 100 mg i.m. either every 2 weeks (30 patients) or 1 week (30 patients). The i.m. injection caused substantial pain at the site of injection, which led to treatment withdrawal in almost 50% of the patients receiving weekly dosing. In control patients, a progressive, slow decline in spine and femoral bone mineral density (BMD), which became statistically significant at the end of the second year of observation, was observed. In the patients given weekly i.m. clodronate, spinal BMD rose by 3.8% (+/-7.3 SD) within 6 months. A slight, nonsignificant increase was observed thereafter, such that, at the completion of 3 years of observation, the mean gain was 4.5% (+/-6.3). In the patients treated with injections of 100 mg of clodronate every two weeks the increase in BMD was somewhat lower and slower, becoming significant only at month 24 (2.9+/-4.6%). In none of the two active groups was the femoral neck BMD changed significantly during the 3 years of the study. A significant increase in trochanter and Ward's triangle BMD was observed at month 12 only in the patients on the highest dose of clodronate. In both groups treated, the hip BMD changes were significantly different from those observed in control patients. The biochemical markers of bone turnover were suppressed in both clodronate groups. These results indicate that intermittent i.m. clodronate administration can provide clinically relevant benefits to skeletal bone density in osteoporotic postmenopausal women, but the in situ pain may limit its extensive use.

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.