Zoledronic acid-associated thrombotic thrombocytopenic purpura.
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Breast Neoplasms↗
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[Effect of 2-methoxyestradiol on proliferation and apoptosis of myeloma cell lines].
The objective was to explore the in vitro effects of growth inhibition and apoptosis induction of 2-methoxyestradiol (2ME2), an estrogen derivative, on seven myeloma cell lines NCI-H929, HS-sultan, KM3, SKO-007, CZ-1, U266 and LP-1and to observe its synergistic effects in combination with some other drugs, such as dexamethasone, As(2)O(3), thalidomide and zoledronic acid. Seven myeloma cell lines NCI-H929, HS-sultan, KM3, SKO-007, CZ-1, U266 and LP-1 were cultured at different concentrations with or without dexamethasone, As(2)O(3), thalidomide and zoledronic acid. Cell viability was assessed by trypan blue assay, plasma cell labeling index (PCLI) was detected by BrdU assay, terminal-deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay were used to determine apoptosis cells in situ. Synergistic effects of 2ME2 in combination with other drugs were judged by King's formula. The results showed that after treatment with 1, 4, 8, 12, 16 micromol/L 2ME2 at 12, 24, 36 and 48 hours respectively, 2ME2 caused a dose- and time-dependent inhibition of the cell viability. The concentration of 50% growth inhibition (IC(50)) was between (20.8 +/- 0.27) and (34.1 +/- 0.57) micromol/L. After treatment with 12 micromol/L 2ME2 within 24 hours, 2ME2 led to a progressive decline in the fraction of S-phase cells by BrdU assay, plasma cell labeling index (PCLI) declined from (30.14 +/- 4.28)% to (14.71 +/- 6.27)% (P < 0.05). After treatment with 1, 4, 8, 12, 16 micromol/L 2ME2 at 12, 24, 36 and 48 hours respectively, 2ME2 can induce a dose- and time-dependent apoptosis of myeloma cell lines. The percentage of apoptosis was between 9% - 33% (P < 0.05). Q value of synergistic effects was between 1.13 to 1.43. It is concluded that 2ME2 can inhibit proliferation and induce apoptosis of myeloma cell lines and has synergistic effects with dexamethasone, As(2)O(3), thalidomide and zoledronic acid.
2-Methoxyestradiol↗
The use of bisphosphonates in men with hormone-refractory prostate cancer: a systematic review of randomized trials.
PURPOSE: A systematic review of randomized controlled trials (RCTs) was performed to assess the benefits of bisphosphonate therapy in men with hormone-refractory prostate cancer (HRPC). METHODS: The literature was searched to identify RCTs or meta-analyses comparing treatment with bisphosphonates to placebo or no treatment. RESULTS: Ten trials that studied clodronate (five trials, 404 patients), pamidronate (two trials, 350 patients), alendronate (one trial, 49 patients), etidronate (one trial, 51 patients), and zoledronic acid (one trial, 643 patients) in men with HRPC and bone metastases met the eligibility criteria. Pain response was the most frequently reported primary outcome (eight trials). Only the smallest trial demonstrated a statistically significant improvement in pain, but other non-statistically significant trends and subgroup analyses showing improvement in pain were observed in six clodronate and pamidronate trials. Three trials reported skeletal-related events (SREs). A trial studying zoledronic acid reported a statistically and clinically significant reduction in the number of patients having at least one SRE; however, there were higher rates of some adverse effects, and quality of life was not improved. CONCLUSION: Zoledronic acid appears to reduce the number of patients having at least one SRE in men with bone metastases from HRPC that are causing minimal or no pain. This benefit should be weighed against the associated toxicities, and the neutral effect on quality of life. Bisphosphonates may reduce bone pain in men with HRPC, but the evidence is less robust. Further investigations to identify the role of bisphosphonates alone and in combination with other therapies proven effective for men with HRPC are warranted.
Diphosphonates↗
Comparative effects of five bisphosphonates on apoptosis of macrophage cells in vitro.
Bisphosphonates (BPs) inhibits bone resorption by reducing osteoclastic activity; they induce osteoclast apoptosis. Pathophysiology of prostheses loosening is complex and implies an inflammatory reaction secondary to the phagocytosis of wear debris by macrophages with a secondary increased bone resorption by osteoclasts. BPs inhibit proliferation and cause cell death in macrophages by induction of apoptosis. We have used mouse macrophage-like J774.1 cells to evaluate the effects of five BPs. J774A.1 cells were cultured in a standard culture medium for 2-days. BPs (alendronate, pamidronate, etidronate, risedronate, zoledronic acid) were added in the medium at concentration of 10(-6) to 10(-4)M during 3 days. Cells were studied by fluorescence microscopy after staining with the fluorescent dye Hoescht H33342 and the percentage of apoptotic cells was determined on 300 nuclei. Cells were analyzed by flow cytofluorometry after staining with annexin V-FITC (for counting apoptotic cells) and propidium iodide (for necrotic/late-apoptotic cells) on 2000 cells. Etidronate did not cause significant apoptosis or necrosis, at any concentration. Alendronate and pamidronate caused apoptosis and death only at very high concentration [10(-4)M]. On the contrary, apoptotic and necrotic cells were evidenced with risedronate or zoledronic acid at lower concentrations. These effects were dose-dependant and occurred when concentration reached [10(-5)M]. The number of apoptotic cells was higher with zoledronic acid and then with risedronate. Cytofluorometry appeared superior to cytologic analysis in the investigation of macrophage apoptosis, since necrotic cells loose contact with the glass slides and are not identifiable in cytological counts. Some amino-BPs appear to induce apoptosis in macrophages.
Animals↗
Mayo clinic consensus statement for the use of bisphosphonates in multiple myeloma.
Bisphosphonates are effective in the prevention and treatment of bone disease in multiple myeloma (MM). Osteonecrosis of the jaw is Increasingly recognized as a serious complication of long-term bisphosphonate therapy. Issues such as the choice of bisphosphonate and duration of therapy have become the subject of intense debate given patient safety concerns. We reviewed available data concerning the use of bisphosphonates in MM. Guidelines for the use of bisphosphonates in MM were developed by a multidisciplinary panel consisting of hematologists, dental specialists, and nurses specializing in the treatment of MM. We conclude that intravenous pamidronate and intravenous zoledronic acid are equally effective and superior to placebo in reducing skeletal complications. Pamidronate is favored over zoledronic acid until more data are available on the risk of complications (osteonecrosis of the jaw). We recommend discontinuing bisphosphonates after 2 years of therapy for patients who achieve complete response and/or plateau phase. For patients whose disease is active, who have not achieved a response, or who have threatening bone disease beyond 2 years, therapy can be decreased to every 3 months. These guidelines were developed in the Interest of patient safety and will be reexamined as new data emerge regarding risks and benefits.
Bone Density Conservation Agents↗
Osteoclast-targeted therapy for prostate cancer.
Skeletal complications are a major cause of morbidity in men with metastatic prostate cancer. Bone metastases cause pain, fractures, spinal-cord compression, and ineffective hematopoiesis. Men without bone metastases are also at risk for skeletal complications. Androgen deprivation therapy (ADT), the mainstay of treatment for metastatic prostate cancer and a routine part of the management for many men with nonmetastatic prostate cancer, decreases bone mineral density, and increases fracture risk. Pathological osteoclast activation plays a central role in both disease and treatment-related skeletal morbidity. Bisphosphonates, potent inhibitors of osteoclast activity, are now an important part of the management for many men with prostate cancer. Zoledronic acid, a potent intravenous bisphosphonate, decreases the risk of skeletal complications in men with hormone-refractory prostate cancer and bone metastases. Zoledronic acid and pamidronate preserve bone mineral density in men receiving ADT for nonmetastatic prostate cancer. Ongoing clinical trials will evaluate the role of osteoclast-targeted therapy in other settings including prevention of treatment-related fractures, prevention of bone metastases in men with high-risk nonmetastatic prostate cancer, and prevention of skeletal complications in men with hormone-sensitive metastatic disease.
Adult↗
[Therapeutic options for hormone-refractory prostate cancer].
For a long time, hormone-refractory prostate cancer was regarded as a chemoresistant tumor. The introduction of taxanes has prompted a change in this opinion. For the first time treatment with 75 mg/m(2) docetaxel every 3 weeks has evidenced a survival benefit in a phase III trial (median survival of 18.9 months versus 16.5 months with mitoxantrone). Further advantages were improved pain reduction and quality of life. Neutropenia was foremost among the side effects. Docetaxel is currently the standard treatment for hormone-refractory prostate cancer. The morbidity of metastatic hormone-refractory prostate cancer is influenced by bone metastases. Pain is a prominent feature. Skeletal complications are frequent. Therapy with 4 mg zoledronic acid reduced skeletal complications significantly in comparison to placebo. The most pronounced effect is the reduction of pathological fractures. Side effects include flu-like symptoms, muscle pain, and edemas. Zoledronic acid also belongs to the standard treatment of hormone-refractory prostate cancer with bone metastases.
Androgen Antagonists↗
Efficacy of bisphosphonates in the management of skeletal complications of bone metastases and selection of clinical endpoints.
Bisphosphonates are the current standard of palliative care for patients with bone lesions from breast cancer and multiple myeloma. This article discusses the selection of endpoints and statistical methods used to assess clinical efficacy of bisphosphonate therapies in patients with bone metastases. Recent studies of pamidronate and zoledronic acid have set the standards for the design and conduct of multicenter, randomized, placebo-controlled trials to assess the clinical benefit of bisphosphonates in patients with bone metastases. Studies of zoledronic acid have demonstrated objective, significant, and enduring benefits in patients with a broad range of primary cancers, including prostate cancer, using robust clinical endpoints. Other bisphosphonates, including clodronate, have been investigated for the treatment of bone metastases, but these studies have been relatively small. This review first considers issues of trial design and analysis, with particular emphasis on the statistical requirements for the rigorous analysis of multiple events occurring in the same patient, and then reviews the results of bisphosphonate trials in patients with breast or prostate cancers metastatic to bone in the light of these statistical considerations.
Bone Neoplasms↗
Transient retention of endochondral cartilaginous matrix with bisphosphonate treatment in a long-term rabbit model of distraction osteogenesis.
UNLABELLED: Bisphosphonates induce major increases in strength of callus in distraction osteogenesis in the short term. Poor understanding of the underlying mechanism, however, raises concerns about long-term consequences. In this long-term study in 32 rabbits, zoledronic acid transiently increased trabeculae by delayed temporal progression of endochondral bone remodeling but did not prevent radiographic completion of bone repair. INTRODUCTION: We hypothesized that bisphosphonate inhibition of osteoclast-mediated resorption would retain bone during repair, producing a larger callus in the short term. However, if remodeling was not restored, completion of the bone repair process in the long term could be jeopardized. MATERIALS AND METHODS: Juvenile rabbits underwent right tibial osteotomy and 2 weeks of distraction, followed by a period of consolidation. Animals received saline (controls) or zoledronic acid (ZA; 0.1 mg/kg at surgery and again 2 weeks later), and distracted tibias were examined by radiograph, DXA, histology, and histomorphometry at 2, 4, 6, 18, and 44 weeks after surgery. RESULTS: Regenerated bone in ZA-treated animals was denser than controls on radiographs at 6 weeks and had more distinct radiodense trabeculae and retention of original cortices at 18 weeks. By 44 weeks, controls and ZA-treated animals were radiographically healed and indistinguishable. Regenerate BMD and BMC increased between 2 and 4 weeks in all animals, with a greater effect in ZA. At 6 weeks, BMD and BMC in ZA-treated animals were 1.6- and 2-fold greater, respectively, than controls (p < 0.01). From 6 to 44 weeks, the control values gradually increased and approached the ZA-treated values. Regenerate bone volume and trabecular number by histomorphometry were from 1.6- to 2-fold greater in ZA-treated animals at 6 and 18 weeks (p < 0.05). Endochondral cartilaginous matrix volume was up to 2.4-fold greater in ZA-treated animals at 2 and 4 weeks (p < 0.05). TRACP+ cells in ZA-treated animals were larger with more nuclei. Mineral apposition rate and osteoblast number and surface were lower in ZA-treated animals at 6 weeks (p < 0.01) but not at later times. CONCLUSIONS: Disruption of TRACP+ cell function by ZA during bone regeneration seems to lead to an accretion of cancellous bone built on a larger endochondral cartilaginous matrix and increased bone mass, consistent with reported increases in short-term callus strength. This increase in bone mass, caused by a delay in remodeling, provided a transient advantage without preventing radiographic completion of the bone repair process in the long term. Noncontinuous treatment with nitrogen-containing bisphosphonates thus can have short-term beneficial effects without preventing long-term bone repair.
Acid Phosphatase↗
Jaw complications associated with bisphosphonate use in patients with plasma cell dyscrasias.
Osteonecrosis of the jaw has been linked with bisphosphonate use in breast cancer and multiple myeloma patients. We report 17 cases of patients with plasma cell dyscrasia being treated with bisphosphonate who developed osteonecrosis/osteomyelitis of the jaw. Seventeen patients evaluated at our institution between 1998 and 2005 are reported. All were being treated with bisphosphonates for a median of 5 mo prior to the onset of jaw symptoms. Sixteen of the 17 patients are 51 yr or older. None of the patients had been irradiated in the jaw nor had obvious osseous manifestation of multiple myeloma in the jaw. Thirteen patients were receiving zoledronic acid and four patients were receiving pamidronate at the onset of jaw symptoms. Six of the 17 did receive both agents at some time and all of these individuals were receiving zoledronic acid at diagnosis. Microorganisms were isolated in 7/17 patients with the most common organism being actinomycosis. We have initiated the following guidelines in an effort to ameliorate the incidence of this complication. Patients should have a full dental examination at the time of diagnosis of the plasma cell dyscrasia especially if bisphosphonates are to be considered as part of the therapy. In addition, bisphosphonates are held for a period of 3 mo prior to invasive dental procedures to allow for the osteoclastic recovery, therefore enhanced debris removal and lessening the chance of creating a fertile bacterial medium. Following the dental procedure we would re-introduce bisphosphonates only after the healing process is complete. Finally, multiple myeloma patients diagnosed with jaw osteonecrosis probably have a concurrent infection and should be aggressively treated with antibiotics.
Adult↗
Moving into the future: treatment of bone metastases and beyond.
In various common cancers, the skeleton is a preferred site of metastasis. It is also threatened by bone loss resulting from anti-cancer therapy. Like bone metastases in advanced cancer, cancer treatment induced bone loss (CTIBL) substantially increases fracture risk and dramatically decreases quality of life and patient autonomy. Both chemotherapy and endocrine deprivation therapy (EDT) can significantly decrease bone mineral density (BMD). This is aggravated by the often long duration of EDT, particularly in the adjuvant setting. Cumulative bone loss can put patients at risk of osteopenia and osteoporosis. With their known efficacy in preventing skeletal complications in metastatic disease, bisphosphonates (BP) lend themselves to exploring their extended use, notably in preventing CTIBL. Clinical trials have shown BPs to effectively prevent and treat CTIBL, for which they are recommended by ASCO guidelines. Whether BPs also have the potential to prevent metastatic dissemination to bone remains to be determined. Zoledronic acid, a third-generation BP with a favourable efficacy/safety record, was shown by ongoing large clinical trials to not only prevent or reduce CTIBL in early stage cancer, but to actually increase BMD. The current evidence of the potential of zoledronic acid in addressing CTIBL and preventing bone metastases is reviewed.
Antineoplastic Agents↗
Current status of treatment for patients with metastatic prostate cancer.
INTRODUCTION: Men with advanced prostate cancer now have many treatment options which include first and second-line hormonal therapy, chemotherapy, radiation therapy, (either directed external beam or systemic radio-istotope), and investigational agents on protocols. Additional adjunctive therapy with the bisphosphonate, zoledronic acid, to reduce skeletal complications should be considered. DISCUSSION: This review will discuss appropriate timing of many of these options and summarize the randomized trials demonstrating survival benefit for docetaxel and decreased skeletal morbidity for zoledronic acid. CONCLUSION: The clinical trials conducted to date do not address the question of when to give chemotherapy in the course of hormone refractory disease and the role of chemotherapy earlier in advanced disease remains to be defined. For the present, clinicians must consider many factors in determining what treatment is appropriate for the individual patient with advanced prostate cancer.
Androgen Antagonists↗
Bisphosphonates to prevent skeletal complications in men with metastatic prostate cancer.
PURPOSE: The literature on clinical trials of bisphosphonates in men with metastatic prostate cancer is reviewed to familiarize the reader with biology of bone metastases and rationale for use of bisphosphonates. MATERIALS AND METHODS: A MEDLINE review of the literature on prostate cancer and bisphosphonates was performed. RESULTS: In uncontrolled clinical trials bisphosphonates improved pain and analgesic scores in men with symptomatic bone metastases. In a randomized controlled trial of men with bone metastases and progressive disease after first line hormonal therapy zoledronic acid decreased the skeletal related events, a composite end point defined as fracture, surgery or radiation therapy to bone, or change in antineoplastic therapy for bone pain. Randomized controlled trials with other bisphosphonates reported no significant benefit in men with bone metastases. Problems with the study populations, drug bioavailability and potency, statistical power and end point definition may have contributed to the negative results of these other studies. CONCLUSIONS: Zoledronic acid decreases the risk of skeletal related events in men with bone metastases and disease progression after first line hormonal therapy. Additional clinical research is needed to evaluate the optimal timing, schedule and duration of bisphosphonate treatment in men with metastatic prostate cancer. Additional research is also necessary to determine whether bisphosphonates can prevent bone metastases in men with high risk nonmetastatic prostate cancer.
Analgesics, Non-Narcotic↗
The role of bisphosphonates in the management of prostate cancer.
Current therapies have extended the survival of patients with prostate cancer. However, these patients often develop skeletal morbidity from disease- and treatment-related effects that undermine skeletal integrity throughout the course of the disease. Low bone mineral density (BMD) is prevalent in patients with early-stage prostate cancer, and androgen-deprivation therapy by either pharmaceutical agent (including hormonal) or surgical castration causes significant decreases in BMD. Fractures can result in a loss of independence and have been associated with shorter survival in patients with prostate cancer. Zoledronic acid is the only bisphosphonate that has demonstrated objective and long-term benefits in reducing skeletal morbidity in patients with bone metastases due to prostate cancer, and it has produced long-term reductions in pain levels compared with placebo in this setting. Therefore, bisphosphonates, particularly zoledronic acid, may provide important benefits for preserving bone health during the course of prostate cancer progression.
Androgen Antagonists↗
Management of primary osteoporosis.
Although there is a great need for better therapeutic approaches to the patient who presents with a fracture, osteoporotic fractures will remain a condition that is more amenable to prevention than treatment. Hormone replacement therapy (HRT) is still considered by many the mainstay for the prevention and the treatment of posrmenopausal osteoporosis. However, there are several controversies regarding HRT, especially the duration of treatment and the risks/benefits ratio. Recent studies have challenged the assumption that HRT conveys real long-term beneficial effects. Raloxifene or other "selective estrogen receptor modulators" (SERMs) should progressively replace HRT in elderly women. Bisphosphonates have demonstrated a clearcut efficacy in the treatment of osteoporosis. Alendronate and risedronate have been the most extensively studied bisphosphonates under randomized controlled trials conditions. Both agents can reduce the risk of vertebral and hip fractures by one-fourth to one-half. However, oral bisphosphonates are not without gastro-intestinal toxicity and strict adherence to constraining therapeutic schemes is mandatory. Intermittent treatments are already in use. Weekly alendronate is as efficient as daily therapy and improves treatment compliance. Newer more potent bisphosphonates, such as oral ibandronate or intravenous zoledronic acid, will allow much less frequent administration. The anti-fracture efficacy of yearly zoledronic acid infusions is thus currently tested. On the other hand, bone-forming agents, such as daily subcutaneous injections of teriparatide (rhPTH 1-34) offer exciting perspectives for the treatment of severe osteoporosis despite the complexity of such therapy.
Absorptiometry, Photon↗
The HORIZON Recurrent Fracture Trial: design of a clinical trial in the prevention of subsequent fractures after low trauma hip fracture repair.
OBJECTIVE: To present the novel design of a trial testing the safety and efficacy of a yearly bisphosponate, zoledronic acid, in preventing new clinical fractures in patients with recent low trauma hip fracture repair. RESEARCH DESIGN AND METHODS: Randomized, placebo-controlled, triple-blind study. One hundred and fifteen clinical centers worldwide are recruiting approximately 1714 subjects aged 50 years and over (no upper age limit, median age of enrolled subjects to date 79 years) who have undergone surgical repair of a low trauma hip fracture in the preceding 90 days. Patients will be assigned at random to an intervention group (5 mg zoledronic acid intravenously yearly) or a control group (placebo infusion yearly). Both groups receive a loading dose of Vitamin D2 or D3 IM or orally, followed by 800-1200 IU Vitamin D and 1000-1500 mg elemental calcium orally on a daily basis. Concomitant therapy with calcitonin, hormone replacement therapy, selective estrogen receptor modulators, tibolone, and external hip protectors are allowed. MAIN OUTCOME MEASURES: The primary endpoint is subsequent skeletal fractures as adjudicated by a clinical endpoints committee blinded to intervention status. Secondary outcomes include delayed hip fracture healing, changes in bone mineral density, and health resource utilization. Subjects will be recruited over a 3-4 year period and will be followed until 211 primary endpoints are accrued and adjudicated. CONCLUSIONS: This randomized clinical trial is novel among osteoporosis therapies as it (1). targets hip fracture patients, a previously understudied group, and (2). uses only clinically evident fractures as the primary outcome. Ethical and practical considerations in studying this frail population are discussed.
Bone Density↗
Management of treatment-related osteoporosis in men with prostate cancer.
Osteoporosis is an important and preventable adverse effect of androgen deprivation therapy for prostate cancer. Androgen deprivation therapy by either bilateral orchiectomies or administration of a gonadotropin-releasing hormone agonist decreases bone mineral density and increases fracture risk. Treatment-related osteoporosis can be prevented by intermittent administration of either intravenous pamidronate or zoledronic acid. Pamidronate (60 mg intravenously every 3 months) prevents bone loss during androgen deprivation therapy. Zoledronic acid (4 mg intravenously every 3 months) not only prevents bone loss but also increases bone mineral density. Alendronate and other oral bisphosphonates may be effective but have not been evaluated in men with castrate testosterone levels. Oestrogen replacement therapy and treatment with selective ooestrogen receptor modulators may prevent bone loss during androgen deprivation therapy. Bicalutamide (150 mg daily) monotherapy increases serum ooestrogen levels and maintains bone mineral density.
Androgen Antagonists↗
Transient disturbance in physeal morphology is associated with long-term effects of nitrogen-containing bisphosphonates in growing rabbits.
UNLABELLED: Bisphosphonates have clinical benefit in children with severe osteogenesis imperfecta or osteoporosis and potential benefit in children with Perthes disease or undergoing distraction osteogenesis. However, there is concern about the effects of bisphosphonates on the physis and bone length. In 44 growing rabbits, zoledronic acid caused a transient disruption of physeal morphology, retention of cartilaginous matrix in trabeculae and cortical bone of the metaphysis, and a minor decrement in tibial bone length at maturity. INTRODUCTION: Data from growing animal models suggest that bisphosphonates cause retention of longitudinal cartilaginous septa at the chondro-osseous junction, extension of trabeculae to the metaphyseal-diaphyseal junction, and varying dose-dependent effects on longitudinal growth. However, there is a lack of data regarding effects of intermittent use of nitrogen-containing bisphosphonates on the physis and on tibial length in models reaching maturity. MATERIALS AND METHODS: Contralateral tibias of juvenile rabbits were examined after right tibial distraction osteogenesis from two previous studies. Animals were randomized to receive 0.1 mg/kg zoledronic acid (ZA) IV at 8 weeks of age (ZA*1) or 8 and 10 weeks of age (ZA*2) or saline. Body mass was analyzed from 5 to 44 weeks of age; tibial length and proximal physeal-metaphyseal histology and histomorphometry were analyzed at 8-52 weeks of age. RESULTS: Tibial length was 3% less at 14 weeks of age in the ZA*2-treated versus saline group (p<0.05) in both studies, and this difference persisted at maturity in the long-term study group (26 weeks of age, p<0.05). Total body mass gain from 5 to 26 weeks of age was 14% less in ZA*2-treated than saline animals (p<0.05). Rate of weight gain from 8 to 10 weeks of age was 76% less in ZA*2 compared with saline animals (p<0.05). Radiographs showed radiodense lines in the metaphyses of ZA-treated bones, corresponding to the number of doses. Histologically, lines resulting from the first dose of ZA contained longitudinal cartilaginous matrix cores surrounded by bone, whereas those from the second dose contained spherical cores of matrix caused by transient disruption of physeal morphology after the first dose of ZA. Resorption of these lines at later times was radiographically and histologically evident, but remnants of cartilaginous matrix remained in the cortical bone of ZA-treated animals. CONCLUSIONS: ZA treatment within the final 13.5% of the rabbit tibial growth period caused a transient disruption in physeal morphology and resorption associated with retention of cartilaginous matrix and coinciding with a persistent 3% decrement in tibial length. Disruption of physeal morphology and potential loss of bone length should be considered when administering nitrogen-containing bisphosphonates to children before closure of the major physes.
Animals↗