The absolute bioavailability of clodronate from two different oral doses

Unexpected chronic lymphocytic leukemia B cell activation by bisphosphonates

Chronic lymphocytic leukemia (CLL) is a disease of the elderly, often presenting comorbidities like osteoporosis and requiring, in a relevant proportion of cases, treatment with bisphosphonates (BPs). This class of drugs was shown in preclinical investigations to also possess anticancer properties. We started an in vitro study of the effects of BPs on CLL B cells activated by microenvironment-mimicking stimuli and observed that, depending on drug concentration, hormetic effects were induced on the leukemic cells. Higher doses induced cytotoxicity whereas at lower concentrations, more likely occurring in vivo, the drugs generated a protective effect from spontaneous and chemotherapy-induced apoptosis, and augmented CLL B cell activation/proliferation. This CLL-activation effect promoted by the BPs was associated with markers of poor CLL prognosis and required the presence of bystander stromal cells. Functional experiments suggested that this phenomenon involves the release of soluble factors and is increased by cellular contact between stroma and CLL B cells. Since CLL patients often present comorbidities such as osteoporosis and considering the diverse outcomes in both CLL disease progression and CLL response to treatment among patients, illustrating this phenomenon holds potential significance in driving additional investigations.

Potential Adverse Effect of Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) on Bisphosphonate Efficacy: An Exploratory Post Hoc Analysis From a Randomized Controlled Trial of Clodronate

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to have weak but beneficial effects on bone health, including fracture risk, but many epidemiological studies are likely confounded. We explored the relationship between NSAIDs and fracture risk in a post hoc analysis of a well-documented, randomized, placebo-controlled study of the bisphosphonate, clodronate, in which treatment reduced osteoporotic fracture risk by 23%. Concurrent medication use at baseline was used to identify those prescribed oral NSAIDs. Only verified, incident fractures were included in the analysis. A total of 1082 (20.8%) women reported use of NSAIDs at baseline. They were slightly, but significantly, younger (mean 79 versus 80 years, p = 0.004), heavier (mean 66.7 versus 64.7 kg, p < 0.001) than nonusers, with slightly higher femoral neck bone mineral density (FN-BMD, 0.66 versus 0.64 g/cm2 , p < 0.001). In an adjusted model, NSAID use was associated with a significant increase in osteoporotic fracture risk over the 3-year study period (hazard ratio [HR] 1.27; 95% confidence interval [CI], 1.01-1.62; p = 0.039). However, this increase in risk was not statistically significant in the placebo group (HR 1.11; 95% CI, 0.81-1.52). In women receiving clodronate, the effect of the bisphosphonate to reduce osteoporotic fracture risk was not observed in those receiving NSAIDs (HR 0.95; 95% CI, 0.65-1.41; p = 0.81) in contrast to those not using NSAIDs (HR 0.71; 95% CI, 0.58-0.89; p = 0.002). In a subset with hip BMD repeated at 3 years, BMD loss during clodronate therapy was greater in those women receiving NSAIDs than in nonusers (eg, total hip -2.75% versus -1.27%, p = 0.078; femoral neck -3.06% versus -1.12%, p = 0.028), and was not significantly different from that observed in women receiving placebo. The efficacy of the bisphosphonate, clodronate, to reduce fracture risk was largely negated in those receiving NSAIDs. Although the mechanism is unclear, this clinically significant observation requires exploration in studies of commonly used bisphosphonates. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Effect of bisphosphonates on the rapidly growing male murine skeleton

Bisphosphonates are effective for preventing and treating skeletal disorders associated with hyperresorption. Their safety and efficacy has been studied in adults where the growth plate is fused and there is no longitudinal bone growth and little appositional growth. Although bisphosphonate use in the pediatric population was pioneered for compassionate use in the treatment of osteogenesis imperfecta, they are being increasingly used for the treatment and prevention of bone loss in children at risk of hyperresorptive bone loss. However, the effect of these agents on the growing skeleton in disorders other than osteogenesis imperfecta has not been systematically compared. Studies were, therefore, undertaken to examine the consequences of bisphosphonate administration on the growth plate and skeletal microarchitecture during a period of rapid growth. C57Bl6/J male mice were treated from 18 to 38 days of age with vehicle, alendronate, pamidronate, zoledronate, or clodronate at doses selected to replicate those used in humans. Treatment with alendronate, pamidronate, and zoledronate, but not clodronate, led to a decrease in the number of chondrocytes per column in the hypertrophic chondrocyte layer. This was not associated with altered hypertrophic chondrocyte apoptosis or vascular invasion at the growth plate. The effects of pamidronate on trabecular microarchitecture were less beneficial than those of alendronate and zoledronate. Pamidronate did not increase cortical thickness or cortical area/total area relative to control mice. These studies suggest that bisphosphonate administration does not adversely affect skeletal growth. Long-term investigations are required to determine whether the differences observed among the agents examined impact biomechanical integrity of the growing skeleton.

ACUTE AND SUBACUTE ORAL TOXICITY TESTS OF SINTERED DICALCIUM PYROPHOSPHATE ON OVARIECTOMIZED RATS FOR OSTEOPOROSIS TREATMENT

Sintered dicalcium pyrophosphate (SDCP) is a synthetic pyrophosphate analog that could be utilized in the treatment for osteoporosis. In this study, an ovariectomized rat model is used to evaluate the systematic toxicity of orally administered SDCP relative to its effects on bone mass. Ovariectomized Wistar rats were treated with experimental medication with different dosing strategies (0.5 mg/kg five days weekly, and 2.5 mg/kg once weekly) for once (acute oral toxicity test) and four weeks (subacute oral toxicity test) followed by recovery period. Clinical signs of toxicity, body weight, and food consumption of rats were recorded. Blood samples were collected for hematological and blood biochemical analyses. Rats were sacrificed for necropsy and major visceral organs were harvested for histological examination after the recovery period. Long bones of four limbs were harvested to evaluate the effects of SDCP on bone mass. Results showed that there was no change in clinical signs, body weight, food consumption, hematology, blood biochemistry, necropsy, and histological examination attributable to the oral administration with SDCP to rats during the dosing period and the recovery period. Analysis of bone ashes revealed that the ovariectomized rats ingested with 0.5 mg/kg SDCP five days weekly continually for four weeks increased bone mineral contents significantly. In the ovariectomized rats ingested with 2.5 mg/kg SDCP once weekly continually for four weeks, the bone mineral contents were increased to normal bone quality. This study indicates that the SDCP can increase bone mass in the ovariectomized rat with no deleterious effects.

Effect of zoledronic acid used in the root surface treatment of late replanted teeth: a study in rats

This study evaluated the use of zoledronic acid, a resorption inhibitor, as a medication for root resorption treatment of late replanted teeth. Twenty-four maxillary right central incisors of rats were avulsed and kept dry for 30 min. Then, the teeth were divided into 2 groups. In group I, root surface was treated with 2% sodium fluoride for 20 min; in group II, 10-6M zoledronic acid solution was used for 20 min. All root canals were filled with calcium hydroxide. Next, teeth were replanted in their respective sockets. After 15 and 60 days post-replantation, the animals were killed and the anatomic pieces were obtained and prepared for microscopic and morphometric analyses. The results showed that zoledronic acid was capable of limiting the occurrence of root resorption and preserving cementum resorption. Further research must be performed to confirm the use of zoledronic acid in root surface treatment of late replanted teeth.

Bisphosphonates significantly increase the activity of doxorubicin or vincristine against canine malignant histiocytosis cells

Canine malignant histiocytosis (MH) is an aggressive neoplasm of macrophages and dendritic cells. It carries a poor prognosis because of the development of widespread metastasis and poor sensitivity to chemotherapy. Thus, there is a large need for new treatments for MH. We hypothesized that bisphosphonates might be useful to increase the effectiveness of cytotoxic chemotherapy against MH. To address this question, we conducted in vitro screening studies using MH cell lines and a panel of 6 chemotherapy and 5 bisphosphonate drugs. The combination of clodronate with vincristine was found to elicit synergistic killing which was associated with a significant increase in cell cycle arrest. Second, zoledronate combined with doxorubicin also significantly increased cell killing. Zoledronate significantly increased the uptake of doxorubicin by MH cells. On the basis of these findings, we conclude that certain bisphosphonate drugs may increase the overall effectiveness of chemotherapy for MH in dogs.

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.

Evaluation of liposomal clodronate for treatment of malignant histiocytosis in dogs

Malignant histiocytosis (MH) is an aggressive cancer derived from myeloid lineage cells in both dogs and humans. In dogs, the tumor is characterized by the rapid development of metastatic tumors in multiple sites, including especially the lungs and lymph nodes. Humans develop an analogous disease known as Langerhans cell histiocytosis, which primarily affects children and young adults. Because these tumors are often resistant to conventional chemotherapy, there is a need for newer therapeutic approaches. Systemic administration of liposomal clodronate (LC) has been shown to effectively deplete phagocytic cells (e.g., macrophages and dendritic cells) in mice. We investigated therefore whether LC could also be used to treat naturally occurring MH in dogs. First, the susceptibility of canine MH cells to LC-mediated killing was assessed in vitro. Then the clinical safety and effectiveness of LC as a treatment for MH was assessed in a pilot study in five pet dogs with spontaneous MH. We found that canine MH cells were very susceptible to LC-induced apoptotic cell death, whereas other tumor cell lines were resistant to killing by LC. Studies using labeled liposomes demonstrated that susceptibility to LC killing was directly related to the efficiency of liposome uptake. In pet dogs with spontaneous MH, we found that a short course of LC treatment elicited significant tumor regression in two of five treated animals. These findings suggest that liposomal delivery of clodronate and possibly other bisphosphonates may offer an effective new approach to treatment of histiocytic neoplasms in dogs and humans.

Disrupting antibiotic resistance propagation by inhibiting the conjugative DNA relaxase

Conjugative transfer of plasmid DNA via close cell-cell junctions is the main route by which antibiotic resistance genes spread between bacterial strains. Relaxases are essential for conjugative transfer and act by cleaving DNA strands and forming covalent phosphotyrosine linkages. Based on data indicating that multityrosine relaxase enzymes can accommodate two phosphotyrosine intermediates within their divalent metal-containing active sites, we hypothesized that bisphosphonates would inhibit relaxase activity and conjugative DNA transfer. We identified bisphosphonates that are nanomolar inhibitors of the F plasmid conjugative relaxase in vitro. Furthermore, we used cell-based assays to demonstrate that these compounds are highly effective at preventing DNA transfer and at selectively killing cells harboring conjugative plasmids. Two potent inhibitors, clodronate and etidronate, are already clinically approved to treat bone loss. Thus, the inhibition of conjugative relaxases is a potentially novel antimicrobial approach, one that selectively targets bacteria capable of transferring antibiotic resistance and generating multidrug resistant strains.

In vitro Comparison of Clodronate, Pamidronate and Zoledronic Acid Effects on Rat Osteoclasts and Human Stem Cell-Derived Osteoblasts

In the present study we compared the first generation non-nitrogen-containing bisphosphonate, clodronate with second and third generation nitrogen-containing bisphosphonates, pamidronate and zoledronic acid in dynamic rat osteoclast resorption and apoptosis assays and in human mesenchymal stem cell-derived osteoblast assay. We found that due to high bisphosphonate-bone binding affinity, bone surface exposure to clodronate for 3 min. had maximal resorption inhibition. The mechanism of action of both clodronate and zoledronic acid involved osteoclast apoptosis, whereas pamidronate had only minor apoptotic effect at dosages, which readily inhibited resorption. Zoledronic acid was not metabolised into an intracellular ATP-analogue in vitro in contrast to clodronate. All bisphosphonates had a dose-dependent inhibitory effect on the human bone marrow mesenchymal stem cell (hMSC)-derived osteoblast calcium deposition. None of the compounds had inhibitory effect on hMSC differentiation. Zoledronic acid was the most potent of all three bisphosphonates in terms of both apoptosis induction and resorption inhibition. Zoledronic acid efficacy might thus use its capacity to trigger osteoclast apoptosis in an unknown, but similar manner to that of the non-nitrogen-containing bisphosphonates. It appears that zoledronic acid has properties of both bisphosphonate classes and could well be the first member of a new class of bisphosphonates, by definition.

Clodronate : a review of its use in the prevention of bone metastases and the management of skeletal complications associated with bone metastases in patients with breast cancer

Clodronate (clodronate disodium, Bonefos) is a non-nitrogen-containing bisphosphonate that inhibits osteoclast activity, and thereby inhibits bone resorption. Clodronate has been extensively used in patients with advanced breast cancer, and is generally well tolerated. In patients with primary breast cancer, clodronate is currently the only bisphosphonate shown to improve survival rates and to reduce the incidence of bone metastases in randomised controlled trials. Further trials in patients with early breast cancer are warranted to confirm results to date and to determine the optimal duration of treatment, as well as the efficacy of the drug compared with other bisphosphonates. In the meantime, clodronate is a well established bisphosphonate which has shown beneficial effects in the prevention of bone metastases and on survival in patients with primary breast cancer.

Discovery, clinical development, and therapeutic uses of bisphosphonates

OBJECTIVE

To review the literature concerning the history, development, and therapeutic uses of bisphosphonates.

DATA SOURCES

English-language articles were identified through a search of MEDLINE (through December 2004) using the key word bisphosphonate. Reference lists of pivotal studies, reviews, and full prescribing information for the approved agents were also examined.

STUDY SELECTION AND DATA EXTRACTION

Selected studies included those that discussed the discovery and initial applications of bisphosphonates, as well as their historical development, pharmacokinetic and pharmacodynamic properties, and current therapeutic uses.

DATA SYNTHESIS

Bisphosphonates structurally resemble pyrophosphates (naturally occurring polyphosphates) and have demonstrated similar physicochemical effects to pyrophosphates. In addition, bisphosphonates reduce bone turnover and resist hydrolysis when administered orally. The information gained from initial work with etidronate generated a considerable scientific effort to design new and more effective bisphosphonates. The PCP moiety in the general bisphosphonate structure is essential for binding to hydroxyapatite and allows for a number of chemical variations by changing the 2 lateral side chains (designated R(1) and R(2)). The R(1) side chain determines binding affinity to hydroxyapatite, and the R(2) side chain determines antiresorptive potency. Accordingly, each bisphosphonate has its own characteristic profile of activity.

CONCLUSIONS

The bisphosphonates reduce bone turnover, increase bone mass, and decrease fracture risk and therefore have a significant place in the management of skeletal disorders including osteoporosis, Paget's disease, bone metastases, osteogenesis imperfecta, and heterotopic ossification.

The Effect of Clodronate on the Integrity and Viability of Rat Small Intestine in Vitro-A Comparison with EDTA

Although substances, which can increase the paracellular permeability of intestinal mucosa, could be very helpful for increasing the bioavailability of hydrophilic drugs, they are not used therapeutically due to the possibilities of acute or long-term toxicity (intestinal inflammations due to penetration of bacterial fragments into subepithelial spaces). In this paper the abilities of a calcium chelator EDTA and clodronate (a first generation bisphosphonate) to increase the paracellular permeability were assessed using rat jejunum in side-by-side diffusion chambers while the viability of the tissue was monitored by transepithelial potential difference. Although clodronate is less potent than EDTA in depleting calcium from the intestinal tissue, it significantly increased the paracellular permeability of viable rat jejunum "in vitro" when tested at 15 mM and higher concentrations (the highest therapeutic dose dissolved in 250 ml gives a 22 mM solution of clodronate). This effect was reversible under "high-calcium" conditions. Since clodronate therapy does not have any long-term consequences it was concluded that a safe, transient increase of small intestinal permeability is possible. However, the acute gastrointestinal undesired effects, which can develop during the therapy with high doses of clodronate, might also occur after oral applications of paracellular permeability enhancers. Namely, 30 mM and higher concentrations of clodronate caused a loss of the tissue viability in all rat jejunal segments tested in "in vitro" conditions. A similar effect was observed with much lower concentrations of EDTA.

Steroid-free medium discloses oestrogenic effects of the bisphosphonate clodronate on breast cancer cells

Tamoxifen is the standard first-line endocrine therapy for breast cancer, but recent data indicate that it is likely to be replaced by the effective aromatase inhibitors (AIs), in both the metastatic and adjuvant settings. Aromatase inhibitors induce complete oestrogen deprivation that leads to clinically significant bone loss. Several ongoing or planned trials combine AIs with bisphosphonates, even more so that recent data reveal that clodronate may reduce the incidence of bone metastases and prolong survival in the adjuvant setting. Bisphosphonates can inhibit breast cancer cell growth in vitro, but they have never been studied in steroid-free medium (SFM), an in vitro environment that mimics the effects of AIs in vivo. Quite surprisingly, in SFM, clodronate stimulated MCF-7 cell growth in a time- and dose-dependent manner by up to two-fold (crystal violet staining assay), whereas it had no mitogenic activity in complete medium. The bisphosphonate similarly increased the proliferation of IBEP-2 cells, which also express a functional oestrogen receptor (ER), while it weakly inhibited the growth of the ER-negative MDA-MB-231 cells. Expectedly, 17beta-oestradiol stimulated the growth of MCF-7 and IBEP-2 cells cultured in SFM, and had no effect on MDA-MB-231 cells. Moreover, partial (4-OH-tamoxifen) and pure antioestrogens (fulvestrant, ICI 182,780), in combination with clodronate, completely suppressed the mitogenic effect of the bisphosphonate, suggesting that it was mediated by an activation of ER. In accordance with this view, clodronate induced ER downregulation, weakly increased progesterone receptor expression, and stimulated the transcription of an oestrogen-responsive reporter gene. In conclusion, we report a previously unknown stimulatory effect of clodronate on MCF-7 cells grown in SFM, in vitro conditions that are potentially relevant to the use of AIs for breast cancer. Moreover, our data suggest that ER is involved in these effects of clodronate on cancer cell growth.

Effects of various absorption enhancers on transport of clodronate through Caco-2 cells

The major disadvantage concerning clinical use of bishosphonate drugs, like clodronate, is their poor and variable absorption after oral administration. The objective of this study was to assess the effects of four different absorption enhancers-palmitoyl carnitine chloride (PCC), N-trimethyl chitosan chloride (TMC), sodium caprate (C10), and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-on the transport of clodronate using Caco-2 cell culture model. The transport experiments were performed in a normal (1.3mM) and in a minimum-calcium concentration (apically calcium-free medium and basolaterally 100 microM calcium concentration). In the normal calcium concentration, a strong enhancement in clodronate permeation was observed with the enhancers: EGTA (2.5mM), TMC (1.5% w/v), and PCC (0.2mM) increased the transport of 1mM clodronate 190-, 20-, and 10-fold, respectively, and the transport of 10mM clodronate 130-, 70-, and 35-fold. In the minimum-calcium concentration, the effects of the absorption enhancers on the transport of clodronate were not so potent: TMC, PCC, and EGTA caused 2- to 20-fold enhancement in clodronate permeation whereas C10 (10mM) was without any effect. According to the results, the permeation of clodronate through Caco-2 cells could be significantly promoted by the absorption enhancers, which cause widening of the tight junctions and, thus, increase the permeability of the paracellular route.