Side-effects of pamidronate

Bisphosphonates in the management of Paget's disease

The first clinical use of bisphosphonates was in Paget's disease of bone (PDB) when disodium etidronate was found to be effective at suppressing metabolic activity of the disease. Subsequently, PDB became a testing ground for many bisphosphonates using changes in alkaline phosphatase (ALP) as the primary outcome measure in clinical trials. Bisphosphonates are now considered to be the treatment of choice for PDB since they are highly effective at suppressing the elevations in bone turnover that are characteristic of the disease. Short term studies have shown that treatment with alendronate and risedronate can promote formation of lamellar bone in affected sites and improve x-ray appearances in some patients. Bisphosphonates have also been shown to improve bone pain in PDB and within the bisphosphonates, zoledronic acid (ZA) is most likely to give a favourable pain response. Many patients with PDB do not have pain however, even when there is increased metabolic activity and more research is needed to find out why this is the case. The effects of bisphosphonates on complications of PDB such as deformity, pathological fractures and deafness have not been adequately studied since most clinical trials have been short term and have not collected information on these important outcomes. The PRISM and PRISM-EZ studies investigated the long-term effects of bisphosphonates in patients with established PDB using a treat-to-target approach and showed that intensive bisphosphonate therapy aimed at normalising ALP was no more effective than symptom directed treatment with bisphosphonates at preventing complications of PDB. The Zoledronate in the Prevention of Paget's Disease (ZiPP) trial, which is currently in progress, seeks to determine whether early intervention with this potent bisphosphonate might be effective in preventing disease progression. Should the ZiPP study yield positive results, genetic testing coupled to prophylactic bisphosphonate therapy might represent a new indication for these highly effective inhibitors of bone resorption in future years.

Management of Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is the term used to describe a group of rare inherited skeletal disorders characterized by a greatly increased risk of fragility fractures (1). Mutations in several genes can cause OI but the condition is most commonly caused by mutations of COLIA1 or COL1A2 resulting in the production of collagen which is abnormal or present in reduced amounts. Fractures in OI are particularly common during childhood but the elevated fracture risk continues throughout life. Bone mineral density (BMD) can be reduced in OI but the magnitude of increase in fracture risk is far greater than can be accounted for by low BMD, highlighting that a key mechanism of bone fragility is reduced bone quality due to defects of bone matrix and mineralization. A multidisciplinary approach is needed to optimize management of OI, with input from physicians, orthopedic surgeons, physiotherapists, occupational therapists, and other allied health professionals. Orthopedic surgery plays a key role both in the fixation of fractures and in the correction of limb deformities. Bisphosphonates have been widely used in the treatment of children and adults with OI. Although there is good evidence that they increase BMD, it is uncertain to what extent they reduce fracture risk. Clinical trials of bone anabolic drugs such as teriparatide and inhibitors of sclerostin have also been studied; although they increase BMD, studies of these agents have not been powered to look at fracture endpoints. Various other treatment modalities including denosumab, and cell therapy have been explored but haven't gained acceptance in routine clinical practice. There have been huge advances in understanding the pathogenesis of OI but these have not been accompanied by advances in treatment. This signals need for well-designed clinical trials with fracture endpoints in OI, both with existing agents and with the newer therapeutic agents that are now starting to emerge.

Prognostic Effect of Bisphosphonate Exposure for Patients With Diagnosed Solid Cancer: A Systematic Review With Meta-Analysis of Observational Studies

Background: Bisphosphonates are widely prescribed for the prevention and treatment of osteoporosis. Recent epidemiological studies indicate that people with bisphosphonate use may have lower cancer risk and have improved survival. The aim of this study is to determine the association between bisphosphonate use and survival outcomes in solid cancer patients using systematic review and meta-analysis.

Methods: A systematic literature search was performed using the PubMed, Embase, and Cochrane databases. Original articles published until April, 2018 were selected. The survival outcome measures assessed included overall survival (OS), cancer-specific survival (CSS) and recurrence-free survival (RFS). Pooled hazard ratio (HR) and their 95% confidence interval (95% CI) were derived using a random-effects model.

Results: Out of 9,742 retrieved citations, six cohort studies and two nested case-control studies satisfying the inclusion criteria were included for analyses. Bisphosphonate use was significantly associated with improved OS (HR 0.84, 95% CI 0.76–0.93), CSS (HR 0.73, 95% CI 0.58–0.90) and RFS (HR 0.72, 95% CI 0.53–0.96). The results of subgroup analyses stratified by major study characteristics were generally consistent with the main findings. For individual cancer type, we found that bisphosphonate use was significantly associated with longer OS for patients with gastroesophageal cancer (HR 0.62, 95% CI 0.40–0.98), as well as longer CSS for patients with breast cancer (HR 0.73, 95% CI 0.55–0.95).

Conclusions: Current evidence indicates that bisphosphonate use is significantly associated with improved survival for patients with solid cancer. However, the prognostic effects in specific solid tumors remains to be confirmed by further large prospective cohort studies.

Role of Pamidronate Disodium in the Treatment of Metastatic Bone Disease

Aims and Background

Bone metastases are a common feature of advanced neoplastic disease and are considered to be among the most frequent causes of pain and complications in oncologic patients. The main objective of the treatment of such patients is to control their symptoms and improve their quality of life. Pamidronate disodium is a second-generation bisphosphonate capable of inhibiting bone resorption (particularly osteoclast activity) without affecting bone reminerali-zation. After a brief introduction concerning the pathophysiology of bone metastases and neoplastic bone pain, we herein present data on the clinical pharmacology and toxicity of bisphosphonates in general, and pamidronate in particular. We conclude by reviewing the literature on the use of pamidronate in phase II and III trials involving patients with metastatic bone disease.

Methods

The paper is based on a review of articles published between 1984 and 1997 selected from the Cancerline and Medline databases.

Results

In the considered phase II and III studies involving patients with bone metastases (breast cancer and multiple myeloma in particular), pamidronate proved to be efficacious in reducing the incidence of pain and skeletal complications, decreasing the excretion of metabolic markers of bone resorption and improving the quality of life. Intravenous infusions of 60-90 mg over a period of 2 hr every 3-4 weeks did not cause any significant toxic effects and was easily managed.

Conclusions

Pamidronate is a bisphosphonate that is efficacious in the treatment of symptomatic bone metastases and can be considered an important therapeutic option in association with systemic treatments, radiotherapy and normal supportive care, especially in patients with breast cancer and multiple myeloma. Further randomized studies are necessary to confirm the positive preliminary results in other neoplasms, analyze the cost/benefit ratio of the treatment, and verify the possibility that, in addition to being used for palliative purposes, pamidronate may also prevent or delay the appearance of bone metastases.

Inflammatory eye reactions with bisphosphonates and other osteoporosis medications: what are the risks?

Inflammatory eye reactions (IERs) are rare but have been associated with medications to treat osteoporosis. The aim of this review is to summarize the current literature on the association between IERs and specific medications to treat osteoporosis (bisphosphonates, selective estrogen receptor modulators, strontium, denosumab and teriparatide). We cover the known epidemiology, potential pathogenic mechanisms and a resume of unanswered questions. Briefly, this review highlights that none of the existing randomized clinical trials were powered to identify these rare adverse events, and the majority of the information available is from spontaneous case reports and case series reporting associations between bisphosphonates and IERs. No case reports describe IERs after other anti-osteoporosis medications. Importantly, some case reports describe recurrence of the IER after affected patients were rechallenged with the same or another bisphosphonate, and that no reported cases resolved without discontinuation of the bisphosphonate. However, three large population-based cohort studies have shown conflicting results between osteoporosis treatments and IERs, but overall these studies suggest that IERs may actually be part of underlying inflammatory disease processes that also cause osteoporosis, rather than due to the medications used to treat osteoporosis themselves. There are no clear pathogenic mechanisms for how bisphosphonates could potentially cause IERs. However, the drug is secreted into the tears by the lacrimal gland and could cause irritation to the mucous membranes with subsequent release of inflammatory mediators, similar to the systemic response typically seen after infusion of bisphosphonates. However, in summary it is still not known whether there is a true causal association between bisphosphonates or other anti-osteoporosis medications and IERs, or whether it is confounding by indication and is actually due to underlying inflammatory diseases that cause both osteoporosis and IERs.

Long-term risks of bisphosphonate therapy

The objective this study was to summarize long-term risks associated with bisphosphonate therapy. Search of relevant medical publications for data from clinical trials, trial extensions, observational studies and post-marketing reports. Trial extensions and modifications did not reveal significant long-term safety issues. Observational data suggest at least as many benefits as risks. Post-marketing reports of musculoskeletal pain, osteonecrosis of the jaw and atypical femur fractures have been widely circulated in the lay press. Most focus on long-terms risks has been on osteonecrosis of the jaw and atypical femur fractures which occur in patients who have not received bisphosphonate therapy but may be more frequent (though still uncommon) in patients who have been on treatment for 5 years or longer. Lower-risk patients may be able to stop treatment after 3-5 years for a “drug holiday,” which mitigates these long-term risks; for higher risk patients, therapy through 6-10 years appears to be advisable and offers more benefits than risks.

Chronic recurrent multifocal osteomyelitis

Chronic recurrent multifocal osteomyelitis (CRMO) is an autoinflammatory bone disease occurring primarily in children and adolescents. Episodes of systemic inflammation occur due to immune dysregulation without autoantibodies, pathogens or antigen-specific T cells. CRMO is characterised by the insidious onset of pain with swelling and tenderness over the affected bones. Clavicular involvement was the classical description; however, the metaphyses and epiphyses of long bones are frequently affected. Lesions may occur in any bone, including vertebrae. Characteristic imaging includes bone oedema, lytic areas, periosteal reaction and soft tissue reaction. Biopsies from affected areas display polymorphonuclear leucocytes with osteoclasts and necrosis in the early stages. Subsequently, lymphocytes and plasma cells predominate followed by fibrosis and signs of reactive new bone forming around the inflammation. Diagnosis is facilitated by the use of STIR MRI scanning, potentially obviating the need for biopsy and unnecessary long-term antibiotics due to incorrect diagnosis. Treatment options include non-steroidal anti-inflammatory drugs and bisphosphonates. Biologics have been tried in resistant cases with promising initial results. Gene identification has not proved easy although research in this area continues. Early descriptions of the disease suggested a benign course; however, longer-term follow up shows that it can cause significant morbidity and longer-term disability. Although it has always been thought of as very rare, the prevalence is likely to be vastly underestimated due to poor recognition of the disease.

Bisphosphonates in the treatment of osteoporosis

Bisphosphonates are widely used in the treatment of osteoporosis to reduce fracture risk. Because of their long retention time in bone and uncommon side effects, questions have been raised about the optimal duration of therapy. Potential side effects appear to be rare and may not be causally related. Although there is no strong science to guide "drug holidays," there appears to be some lingering antifracture benefit when treatment is stopped, so some time off treatment should be offered to most patients on long-term bisphosphonate therapy. For most patients with osteoporosis, the benefits of treatment outweigh the risks.

Investigation of alendronate-doped apatitic cements as a potential technology for the prevention of osteoporotic hip fractures: critical influence of the drug introduction mode on the in vitro cement properties

Combination of a bisphosphonate (BP) anti-osteoporotic drug, alendronate, with an apatitic calcium phosphate cement does not significantly affect the main properties of the biomaterial, in terms of injectability and setting time, provided that the BP is introduced chemisorbed onto calcium-deficient apatite, one of the components of the cement. In contrast to other modes of introducing the BP into the cement formulation, this mode allows to minimize alendronate release in the cement paste, thus limiting the setting retardant effect of the BP. An original approach based on high frequency impedance measurements is found to be a convenient method for in situ monitoring of the cement setting reaction. The release profile of the drug from a cement block under continuous flow conditions can be well described using a coupled chemistry/transport model, under simulated in vivo conditions. The results show that the released alendronate concentration is expected to be much lower than the cytotoxic concentration.

Osteoporosis update from the 2010 santa fe bone symposium

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

Effect of alendronate on pseudomembrane cytokine expression in patients with aseptic osteolysis

To determine whether alendronate alters the pseudomembrane inflammatory cytokine profile in patients with established aseptic osteolysis. A prospective, double-blind, randomized, controlled trial was conducted. Ten individuals listed for revision surgery for aseptic failure of a primary cemented arthroplasty were randomly assigned placebo/alendronate 70 mg once weekly for 8 weeks before revision surgery. Formalin-preserved pseudomembrane samples were paraffin-sectioned for immunohistochemical analysis to assess inflammatory cytokine protein expression. Polymerase chain reaction was carried out to assess expression of relevant mRNA. No significant difference was detected in the inflammatory cytokine protein or mRNA expression between groups. Alendronate 70 mg administered for an 8-week period before surgery did not alter the pseudomembrane inflammatory cytokine profile in patients with established aseptic osteolysis. Any potential biological effects may occur due to downstream effects on osteoclast and osteoblast function.

The neurological safety of epidural pamidronate in rats

Background

Pamidronate is a potent inhibitor of osteoclast-mediated bone resorption. Recently, the drug has been known to relieve bone pain. We hypothesized that direct epidural administration of pamidronate could have various advantages over oral administration with respect to dosage, side effects, and efficacy. Therefore, we evaluated the neuronal safety of epidurally-administered pamidronate.

Methods

Twenty-seven rats weighing 250-350 g were equally divided into 3 groups. Each group received an epidural administration with either 0.3 ml (3.75 mg) of pamidronate (group P), 0.3 ml of 40% alcohol (group A), or 0.3 ml of normal saline (group N). A Pinch-toe test, motor function evaluation, and histopathologic examination of the spinal cord to detect conditions such as chromatolysis, meningeal inflammation, and neuritis, were performed on the 2nd, 7th, and 21st day following administration of each drug.

Results

All rats in group A showed an abnormal response to the pinch-toe test and decreased motor function during the entire evaluation period. Abnormal histopathologic findings, including neuritis and meningeal inflammation were observed only in group A rats. Rats in group P, with the exception of 1, and group N showed no significant sensory/motor dysfunction over a 3-week observation period. No histopathologic changes were observed in groups P and N.

Conclusions

Direct epidural injection of pamidronate (about 12.5 mg/kg) showed no neurotoxic evidence in terms of sensory/motor function evaluation and histopathologic examination.

Long-term use of bisphosphonates in osteoporosis

CONTEXT

Bisphosphonates have been widely used in the treatment of osteoporosis. Uncommon side effects have emerged in postapproval use. Because bisphosphonates accumulate in bone and are released for months or years after treatment is stopped, it is reasonable to consider the clinical question of how long to treat.

OBJECTIVE

In this personal perspective, we review the pharmacology and mechanism of action of bisphosphonates and the clinical studies that support their efficacy. We then review the literature for longer-term studies and reports of possible side effects that were not seen in clinical trials.

RESULTS

Bisphosphonates have demonstrated antifracture efficacy in randomized, placebo-controlled trials of 3 and 4 yr duration and have been widely used since the initial release of alendronate in 1995. For zoledronic acid and risedronate, an early effect (fractures reduced within 6-12 months of starting therapy) has been shown. A sustained effect for risedronate has been shown through 5 yr and suggested through 7 yr. Ten-year data with alendronate and 8 yr data with risedronate indicated good tolerability and safety; it is unlikely that longer-term studies will be done. Side effects that emerged in clinical trials include esophageal irritation with oral administration and acute phase response with iv treatment or high-dose oral therapy. Uncommon side effects that have been noted with wide clinical use include osteonecrosis of the jaw, musculoskeletal complaints, and atypical fractures. The numbers of events are small, and a clear cause-and-effect relationship between these events and bisphosphonate treatment has not been established. Because bisphosphonates accumulate in bone, they create a reservoir leading to continued release from bone for months or years after treatment is stopped. Studies with risedronate and alendronate suggest that if treatment is stopped after 3-5 yr, there is persisting antifracture efficacy, at least for 1-2 yr.

CONCLUSIONS

Bisphosphonates are popular and effective for treatment of osteoporosis. Because they accumulate in bone and provide some residual antifracture reduction when treatment is stopped, we recommend a drug holiday after 5-10 yr of bisphosphonate treatment. The duration of treatment and length of the holiday are based on fracture risk and pharmacokinetics of the bisphosphonate used. Patients at mild risk might stop treatment after 5 yr and remain off as long as bone mineral density is stable and no fractures occur. Higher risk patients should be treated for 10 yr, have a holiday of no more than a year or two, and perhaps be on a nonbisphosphonate treatment during that time.

Pathogenesis and management of Paget's disease of bone

Paget's disease of bone is a common disease characterised by focal areas of increased bone turnover, affecting one or several bones throughout the skeleton. Paget's disease is often asymptomatic but can be associated with bone pain and other complications such as osteoarthritis, pathological fracture, bone deformity, deafness, and nerve compression syndromes. Genetic factors have an important role in this disease, and mutations have been identified in four genes that cause Paget's disease and related syndromes. The most important of these is Sequestosome 1 (SQSTM1), which is a scaffold protein in the nuclear factor kappaB (NFkappaB) signalling pathway. Patients with SQSTM1 mutations have severe Paget's disease of bone and a high degree of penetrance with increasing age. Environmental factors also contribute. Most research has focused on paramyxovirus infection as a possible trigger, but evidence for this notion is conflicting. Other potential triggers include deficiency of dietary calcium and repetitive mechanical loading of the skeleton. Medical management of Paget's disease of bone is based on giving inhibitors of osteoclastic bone resorption, and bisphosphonates are the treatment of first choice. Bisphosphonate therapy is primarily indicated for patients who have bone pain arising from increased metabolic activity in affected bones. Bisphosphonate therapy is highly effective at reducing bone turnover, and it has been shown to heal radiological lesions and restore normal histology; however, the long-term effects of bisphosphonates on disease progression have not been adequately studied. No firm evidence as yet exists to show that bisphosphonates can prevent the development of complications of Paget's disease of bone, and further work is needed to address the effects of treatment on long-term clinical outcome.

Extra-skeletal effects of bisphosphonates

Bisphosphonates are pharmacological agents which are currently used both in osteoporosis than in other pathological conditions characterised by an increased bone resorption, such as Paget's disease of bone, malign hypocalcaemia during myeloma, osteolytic bone metastasis and fibrous dysplasia of bone. The most important biological effect of bisphosphonates is the reduction of bone remodelling through the inhibition of osteoclastic activity, but there are many clinical and experimental evidences of extra-skeletal biological effects of bisphosphonates. It has been shown that bisphosphonates exert their effects not only on bone tissue cells, but also on those of the immune system with an "immuno-modulating" effect, influencing the production of pro- and anti-inflammatory cytokines and changing the molecular expression involved in the immune processes and anti-inflammatory response. Although the available data are conflicting, there are several reports concerning the beneficial effects of bisphosphonates in controlling the progression of chronic joint inflammatory diseases, suggesting a wider use for these therapeutic agents in clinical practice.

Advances in the management of corticosteroid-induced osteoporosis with bisphosphonates

Corticosteroids are widely used as anti-inflammatory and immunosuppressive agents to treat a variety of chronic conditions. Long-term (>1 year) corticosteroid use can lead to bone loss, and therefore, osteopenia or osteoporosis. Corticosteroid-induced osteoporosis (CIO) leads to increased bone fragility and subsequently fractures, which, in turn, lead to a loss of physical, emotional and social health for the patient and increased costs for healthcare providers. A wealth of data exists demonstrating the efficacy of the oral bisphosphonates, etidronate, alendronate and risedronate in increasing bone mineral density in patients with CIO or preventing bone loss in patients commencing corticosteroid therapy. Data regarding fracture prevention are less clear, as statistically significant reductions in the incidence of fractures have only been reported for patient subgroups or meta-analyses. However, many treatment guidelines recommend the use of oral bisphosphonates for the prevention and treatment of CIO. These guidelines are, however, not reflected in prescribing practice, and the majority of patients do not receive adequate concomitant therapy. This review summarizes the available data for bisphosphonates in CIO. Therapeutic adherence with oral bisphosphonates is an issue, with approximately 50% of patients discontinuing therapy within the first year. The primary reasons for this are poor gastrointestinal tolerability and the frequency with which complex dosing requirements must be followed. The inconvenience of taking daily or weekly bisphosphonate therapy is of particular importance in patients with CIO who may be regularly taking several other medications. Data obtained in studies with ibandronate indicate that bisphosphonate administration by rapid intravenous injection provides an effective, well-tolerated and practical alternative to current oral regimens in the management of patients with CIO.

Management of the adverse effects associated with intravenous bisphosphonates

Intravenous bisphosphonates are widely used to treat hypercalcemia and to reduce skeletal-related morbidity among cancer patients. However, serious complications, generally occurring in less than 2% of patients participated in phase III clinical trials, including acute systemic inflammatory reaction, ocular inflammation, renal failure, nephrotic syndrome, electrolyte imbalance, and osteonecrosis of the maxilla and mandible have all been increasingly reported. Yet, strategies to deal with these complications are becoming clear. Acute systemic inflammatory reaction is often self-limited and becomes less intense during subsequent treatments. For patients who develop ocular symptoms, prompt ophthalmologic evaluation is crucial to determine the safety of a subsequent bisphosphonate therapy. Patients who receive long-term pamidronate should be evaluated at intervals for early sign of nephritic syndrome as timely cessation of the agent may result in a full recovery. To reduce the risk of severe electrolyte abnormalities, particularly hypocalcemia, correcting any pre-treatment electrolyte abnormality and supplementing vitamin D and calcium may be helpful. Finally, to reduce the risk of osteonecrosis of the maxilla and mandible, obtaining a full dental evaluation before treatment and avoidance of invasive dental procedures is suggested. The three commonly used intravenous bisphosphonates (pamidronate, zoledronic acid, and ibandronate), are generally safe; ibandronate has to date been the least reported to be associated with renal side effects. As clinical indications of intravenous bisphosphonates continue to expand, prescribing clinicians should be familiar with these possible adverse effects and discuss them with patients before commencing or continuing on therapy.

Effect of a convenient single 90-mg pamidronate dose on biochemical markers of bone metabolism in patients with acute spinal cord injury

BACKGROUND/OBJECTIVE

To describe the biochemical and adverse effects of a convenient single 90 mg pamidronate dose in patients with acute spinal cord injury (SCI) and compare these effects with those observed in a previous similar study using a 30 mg/d x 3-day pamidronate dosing regimen.

STUDY DESIGN

Retrospective cohort study.

SETTING

University-based rehabilitation center in New York City.

METHODS

A total of 32 patients with SCI were evaluated for biochemical response and adverse events associated with pamidronate therapy. All patients were screened at or near admission for acute rehabilitation, received calcium (1,000 mg daily) and calcitriol (0.25 micrg daily) therapy daily, and on day 4, received a single dose of pamidronate, 90 mg by intravenous infusion, over 4 hours. Serum calcium and phosphate levels were closely monitored, and 2 weeks after pamidronate, biochemical bone markers were re-evaluated.

RESULTS

Responses of biochemical markers of bone resorption (N-telopeptide and 24-hour urinary calcium excretion) to pamidronate 90 mg were consistent with an antiresorptive effect, although less than that observed with a 30 mg/d x 3-day pamidronate dosing regimen. The frequency of hypocalcemia was greater, and hypophosphatemia was less than the 30 mg/d x 3-day pamidronate dosing regimen. Fever was more frequent (78%) with the 90-mg single dose of pamidronate compared with the 30 mg/d x 3-day pamidronate dosing regimen (20%).

CONCLUSIONS

Single-dose pamidronate 90 mg is effective at reducing biochemical markers of bone hyperresorption in patients with acute SCI but is associated with a greater incidence of fever compared with a 30 mg/d x 3-day dosing regimen.

Current management strategies for hypercalcemia

The two most common causes of hypercalcemia are primary hyperparathyroidism and neoplastic disease. Parathyroidectomy is the only curative intervention for the former condition. In the rare cases of patients with primary hyperparathyroidism who present with clinical symptoms due to their hypercalcemia, pharmacological treatment may be required. Fluid repletion and intravenous (IV) administration of bisphosphonates are recommended in the literature. Calcium receptor agonists (calcimimetic agents) are at the present time only available for use within clinical trials. Cancer patients usually present with symptoms of hypercalcemia. Rapid institution of antihypercalcemic treatment is essential in preventing life-threatening deterioration. Fluid repletion and administration of bisphosphonates are the treatment mainstays in hypercalcemia of malignancy. Five bisphosphonates are currently licensed in Europe for treatment of tumor-associated hypercalcemia: etidronate, clodronate, pamidronate, ibandronate, and zoledronate. In the US, pamidronate and zoledronate are licensed for use in this indication. Bisphosphonates containing nitrogen atoms (e.g. pamidronate, ibandronate, and zoledronate) are more potent than those without (e.g. etidronate, clodronate, and tiludronate). In patients with malignant hypercalcemia, the efficacy of the individual bisphosphonate depends on dose administered and initial serum calcium concentration. At present, pamidronate has been studied in the greatest number of investigations and in the largest number of patients. In the literature, the efficacy of pamidronate in restoring normocalcemia ranges between 40% and 100%, depending on the dose used and baseline serum calcium concentration. More recently, one study reported that pamidronate was inferior to zoledronate. In this study, the duration of response was also longer in the two zoledronate groups (30 and 40 days) than in the pamidronate group (17 days). The most serious adverse events of bisphosphonates concern renal function. Increases in serum creatinine levels have been more frequently reported following treatment of tumor-associated hypercalcemia with etidronate (8%) and clodronate (5%) than with the nitrogen-containing bisphosphonates pamidronate (2%) and ibandronate (1%). The frequency of increases in serum creatinine levels following treatment with zoledronate is difficult to estimate. Administration of the nitrogen-containing bisphosphonates has been associated with transient (usually mild) fever, lymphocytopenia, malaise, and myalgias. These events occur within 36 hours of the first dose and are self-limiting. Hypocalcemia occurs in up to 50% of patients treated with bisphosphonates for hypercalcemia of malignancy, although symptomatic hypocalcemia is rare. The toxicity and low efficacy of plicamycin (mithramycin) mean that use of this agent should be restricted to patients with hypercalcemia of malignancy who fail to respond to IV bisphosphonates. Calcitonin is characterized by good tolerability but poor efficacy in normalizing the serum calcium level. However, a major advantage of calcitonin is the acute onset of the hypocalcemic effect, which contrasts with the delayed but more pronounced effect of bisphosphonates. Combination calcitonin and bisphosphonate treatment may therefore be of value when rapid reduction of serum calcium is warranted. Gallium nitrate may be a valuable treatment for hypercalcemia of malignancy. It is characterized by high efficacy and few adverse events apart from renal toxicity (10% of cases). However, data are very limited and further trials are necessary.

The bisphosphonate acute phase response: rapid and copious production of proinflammatory cytokines by peripheral blood gd T cells in response to aminobisphosphonates is inhibited by statins

The bisphosphonates are a novel class of drug that have been registered for various clinical applications worldwide. Bisphosphonates, and in particular the aminobisphosphonates (nBPs), are known to have a number of side-effects including a rise in body temperature and accompanying flu-like symptoms that resemble a typical acute phase response. The mechanism for this response has been partially elucidated and appears to be associated with the release of tumour necrosis factor (TNF)alpha and interleukin (IL)6, although the effector cells that release these cytokines and the mechanism of action remain enigmatic. Here, we show that the nBP-induced acute phase response differs from the typical acute phase response in that CD14+ cells such as monocytes and macrophages are not the primary cytokine producing cells. We show that by inhibiting the mevalonate pathway, nBPs induce rapid and copious production of TNFalpha and IL6 by peripheral blood gammadelta T cells. Prior treatment with statins, which inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, blocks nBP-induced production of these proinflammatory cytokines by gammadelta T cells and may offer a means of avoiding the associated acute phase response. In addition, our findings provide a further mechanism for the anti-inflammatory effects attributed to inhibitors of HMG CoA reductase.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Safety and Convenience of a 15‐Minute Infusion of Zoledronic Acid

Skeletal morbidity, including hypercalcemia of malignancy (HCM), places a severe burden on patients with advanced cancers. Bisphosphonates effectively correct HCM and reduce skeletal morbidity in patients with bone metastases. However, with the widespread use of bisphosphonates, the safety and convenience of therapy are emerging concerns. The delivery of effective doses of early bisphosphonates required a lengthy 24-hour i.v. infusion protocol because of renal tolerability issues. The introduction of more potent bisphosphonates with superior tolerability profiles has allowed therapy to be safely delivered via shorter i.v. infusions. Intravenous therapy with etidronate, clodronate, pamidronate, ibandronate, and zoledronic acid has been used to treat HCM and skeletal complications in cancer patients. Of these therapies, zoledronic acid (which can be safely administered via a 15-minute i.v. infusion) is the most convenient and effective and has demonstrated an excellent safety profile with long-term use. Zoledronic acid has also received the broadest regulatory approval of any bisphosphonate and can be used to treat HCM or bone lesions secondary to multiple myeloma and a wide variety of solid tumors, including breast, prostate, and lung cancers. In addition to the patient preference for shorter infusion times, the 15-minute i.v. infusion protocol of zoledronic acid can provide benefits for infusion centers by potentially increasing patient throughput.

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.

Treatment of osteoporosis: current status and recent advances

With the advent of new treatment choices, osteoporosis should no longer be considered an inevitable part of aging but rather a disease that can be treated. This article provides an overview of recent advances in treatment of osteoporosis.

Efficacy and tolerability of cyclical intravenous pamidronate in patients with low bone mass

Oral bisphosphonates are an established mode of therapy for the prevention and treatment of osteoporosis. However, many patients are unable to take them either because of poor tolerability or some established contraindications. This retrospective study describes our clinical experience with the efficacy and tolerability of cyclical intravenous pamidronate in patients with osteopenia or osteoporosis at the American University of Beirut Medical Center. Twenty patients received intravenous pamidronate, as a 30-mg infusion administered intravenously over 2 h every 3 mo. All patients were maintained on calcium and vitamin D supplementation: 1000 mg of calcium and 400-800 IU of vitamin D, respectively. Bone mineral densities of the spine and/or hip were measured at baseline and within an average of 14 mo of study entry while on cyclical pamidronate. Two-thirds of patients had a significant increase in bone mineral density either at the lumbar spine or hip. Five patients (25%) developed the expected acute-phase reaction symptoms. Pamidronate constitutes an attractive alternative therapy in patients who cannot tolerate oral bisphosphonates.

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.

Steroid-induced osteoporosis in systemic lupus erythematosus

The patient with SLE is at considerable risk of osteoporosis, because of the inflammatory disease itself, its consequences, and its treatments. Because of their extensive use, glucocorticoids are thought to be the most frequent cause of drug-related osteoporosis and may be responsible for much of the bone loss in lupus. This article focuses on the mechanisms of steroid-induced osteoporosis in SLE and outlines strategies for prevention and treatment.

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.

Effects of tiludronate and ibandronate on the secretion of proinflammatory cytokines and nitric oxide from macrophages in vitro

Bisphosphonates inhibit osteoclastic bone resorption and are used for the treatment of bone diseases. Some bisphosphonates, such as clodronate and tiludronate, can be incorporated into non-hydrolysable ATP analogues in cells, whereas the more potent anti-resorptive aminoalkylbisphosphonates are not metabolised. Furthermore, clodronate inhibits proinflammatory cytokine and nitric oxide (NO) secretion from activated macrophages in vitro and has anti-inflammatory properties in vivo, especially when delivered into cells by liposomes. By contrast, aminobisphosphonates can induce an acute phase response and fever in vivo, which appears to involve the induction of cytokine secretion. In this study we examined the effect of liposome-mediated intracellular delivery of one aminobisphosphonate, ibandronate, and one metabolizable bisphosphonate, tiludronate, on the secretion of inflammatory mediators. The intracellular uptake of bisphosphonates by macrophages was enhanced by a factor of 20-200 by using liposomes. Tiludronate dose-dependently inhibited both cytokine and NO secretion from activated macrophages, and liposomal tiludronate was more potent than the free drug. By contrast, ibandronate enhanced LPS-induced secretion of IL-1beta and IL-6 but did not affect TNFalpha or NO secretion at non-cytotoxic concentrations. The present results, together with our previous studies, strongly suggest that bisphosphonates can be grouped into those that are metabolised by cells and that are capable of inhibiting cytokine and NO secretion from macrophages, thus having potential anti-inflammatory properties, and those that are not metabolised but can actually enhance the production of cytokines following macrophage activation.

Immobilization hypercalcemia in incomplete paraplegia: successful treatment with pamidronate

Immobilization hypercalcemia (IH) occurs in adolescent patients with high-level complete tetraplegia, but it has not been reported in patients with incomplete paraplegia. We describe two adolescent patients with low-level incomplete paraplegia who developed IH during comprehensive rehabilitation. Conventional therapies with hydration, diuresis, and calcitonin were not effective. Finally, a single-dose infusion of pamidronate, an amino-bisphosphonate, completely resolved the hypercalcemia. Although it has a pharmacologic profile similar to etidronate, pamidronate is more potent, being effective in a single dose, has fewer adverse effects, and has a longer action than etidronate. These features make pamidronate more suitable for the treatment of severe IH in rehabilitation settings. It is reasonable to consider immobilization as the cause of hypercalcemia in low-level incomplete paraplegic patients who have other contributing factors.

Interleukin-6 and tumor necrosis factor alpha levels after bisphosphonates treatment in vitro and in patients with malignancy

Bisphosphonates are potent inhibitors of bone resorption and are widely used in the treatment of bone diseases. One of the side effects of administered aminobisphosphonates is transient fever and some biological changes that are suggestive of an acute phase response. Pamidronate [(3-amino-1-hydroxypropylidene).1, 1-bisphosphonate] and ibandronate [1-hydroxy-3-(methylpentylamino) propylidenebisphosphonate] incubated in heparinized whole blood at doses of 10(-4) and 10(-5) mol/L, induced the production of tumor necrosis factor alpha (TNFalpha). Moreover, pamidronate was found to slightly stimulate interleukin-6 IL-6 production. In contrast, clodronate (dichloromethylenebisphosphonate) did not increase IL-6 or TNFalpha. To investigate these phenomena in vivo, acute phase reaction was assessed in patients with malignant disease treated with 60 mg of pamidronate (n = 29), 1500 mg of clodronate (n = 8), or 0.5-2 mg of ibandronate (n = 6), all given intravenously. A significant decrease in lymphocyte and leukocyte count was observed in the pamidronate group. In the same group, seven patients (24%) showed a transient increase of body temperature above 37 degrees C with an increase > or = 0.5 degrees C at 24 h. These changes were not found in the patients treated with clodronate or ibandronate. Plasma IL-6 and TNFalpha levels increased significantly after pamidronate treatment, whereas no change was seen after clodronate infusion. The peak of IL-6 level (53.7 +/- 14.1 [SEM] pg/mL) was observed at 24 h, and that of TNFalpha level (26.9 +/- 3.4 pg/mL) at 48 h after the beginning of pamidronate administration (values before treatment, respectively: 28.6 +/- 7.1 pg/mL, p < 0.006; and 13.1 +/- 1.5 pg/mL, p = 0.0001). The peak of C-reactive protein (CRP) level was found at 48 h (41.0 +/- 7.8 vs. 25.5 +/- 5.6 mg/L before treatment, p < 0.01) and CRP levels were strongly correlated with IL-6 levels (p = 0.65,p < 0.001). Only one patient treated with ibandronate showed an increase in IL-6 and CRP levels. Patients treated with pamidronate, whose body temperatures were increased at 24 h, had a greater increases of circulating IL-6, TNFalpha, and CRP at 24 h and 48 h than patients without temperature increase. These results suggest that pamidronate treatment, but not clodronate and possibly not ibandronate at the doses used, induced an increase in the plasma levels of IL-6 and TNFalpha, which may be responsible for the acute phase reaction observed clinically.

Effects of intravenous pamidronate therapy on Paget's disease of bone

Pamidronate is a second generation bisphosphonate that has been used in Europe for the treatment of Paget's disease of bone for several years. It relieves pain and reduces bone turnover in Paget's disease. To assess the effects of pamidronate on Paget's disease of bone, the authors treated 28 patients, aged 45 to 87, with longstanding Paget's disease for a period of 4-18 months. Parameters measured included pain and serum alkaline phosphatase, urinary hydroxyproline, and ionized calcium concentrations. Patients were organized into two groups. Patients in the first group had initial alkaline phosphatase concentrations below 215 U/L, which decreased to normal after one dose of pamidronate. Patients in this group also experienced symptomatic improvement. Patients in the second group had initial alkaline phosphatase values greater than 240 U/L, which did not normalize after 2-11 pamidronate infusions. More patients in this latter group did not report symptomatic improvement. Patients in the second group also had a higher incidence of hypocalcemia. It is concluded that there is a clear relation between initial alkaline phosphatase level in Paget's disease and response to treatment with pamidronate. The authors' current protocol for treating patients with pamidronate is based on this relation. Because pamidronate proved most effective when used in mild Paget's disease, therapy probably should be instituted early in the course of disease.

Pamidronate disodium and possible ocular adverse drug reactions

Ciba-Geigy Central Epidemiology and Drug Safety Center has received 23 reports of suspected ocular adverse drug reactions associated with the use of intravenous pamidronate disodium, an inhibitor of bone resorption that is used primarily in the management of tumor-induced hypercalcemia and Paget's disease of the bone. Anterior uveitis, bilateral in six of seven patients, occurred within 24 to 48 hours after the drug was administered. The anterior uveitis recurred in four of the five patients who were rechallenged. Three reports involved unilateral episcleritis or scleritis occurring within one to six days after the administration of the drug. Only the episcleritis patient was rechallenged five months later, when the patient again had the episcleritis occur in the same eye. Thirteen patients reported nonspecific transitory conjunctivitis within six to 48 hours after pamidronate disodium was given intravenously. This was positive on rechallenge in six of eight patients. These data indicate that, on rare occasions, pamidronate disodium is a probable cause of anterior uveitis or nonspecific transitory conjunctivitis and is a possible cause of episcleritis or scleritis.

Treatment of malignant hypercalcaemia with aminohexane bisphosphonate (neridronate)

Twenty patients with hypercalcaemia due to malignancy, which persisted following rehydration, were treated with the bisphosphonate, aminohexane bisphosphonate (AHBP), which is structurally similar to pamidronate. The treatment given was a single infusion of 125 mg of AHBP in 500 ml of normal saline infused over 4 h. Serum and urine biochemistry were measured before and after treatment. Acute toxicity was evaluated with particular attention to gastrointestinal symptoms, acute-phase reaction and change in renal function, as judged by serum creatinine. The infusion of AHBP induced a rapid fall apparent by day 3 (P < 0.001), with a nadir at day 7. The serum calcium remained lower at days 14 and 28 than at day 0, but the numbers followed up were low (n = 5 and n = 4). In all 20 patients there was a fall in serum calcium after treatment, and in 13 (65%) normocalcaemia was achieved. Failure to respond completely to AHBP appeared to be associated with a renal mechanism of hypercalcaemia. Treatment was associated with a significant decrease in fasting urinary calcium excretion (P < 0.05). There was no change in white cell count or renal function following AHBP and only two cases of mild pyrexia after infusion. We conclude that aminohexane bisphosphonate is an effective agent in the treatment of tumour-induced hypercalcaemia, with rapid onset of effect and low toxicity.

Effective treatment of malignant hypercalcaemia with a single intravenous infusion of clodronate

Thirty patients with hypercalcaemia due to malignancy that persisted following rehydration, were treated with a single dose of the bisphosphonate, clodronate. Clodronate (1.5 g) was administered intravenously in 500 ml normal saline over 4 h. Serum and urine biochemistry were measured before and after treatment and the results were compared with data from 15 patients given the recommended regimen 300 mg intravenous clodronate daily for 5 consecutive days. The single infusion induced a rapid and significant fall in serum calcium, apparent at day 3 (P < 0.0001) that persisted to the end of follow-up at day 10 (P < 0.001). Eighty per cent (24/30) of patients became normocalcaemic. The response was associated with a significant decrease in fasting urinary calcium excretion, and no change in renal function, as judged by serum creatinine. The same dose of clodronate, given as 5 daily infusions, induced a comparable decrease in serum calcium, but was less rapid in onset so that at day 3 the serum calcium was significantly lower with the single infusion (P = 0.02). The calcium lowering effect of both regimens depended on the tumour type. We conclude that the single infusion of 1500 mg clodronate is as effective in reducing serum calcium as the same dose given over 5 days. The single infusion has a more rapid onset of effect, is more convenient than multiple infusions, and has no adverse effect on renal function.

Intravenous pamidronate in the treatment of osteoporosis associated with corticosteroid dependent lung disease: an open pilot study

BACKGROUND

Bisphosphonates have been shown to be effective agents in the treatment of postmenopausal osteoporosis. Because corticosteroid associated osteoporosis is often associated with increased bone turnover, the effect of intermittent intravenous infusions of pamidronate on this condition has been investigated.

METHODS

Seventeen patients (five male) with chronic corticosteroid dependent lung disease (15 asthma, two sarcoidosis) were treated with infusions of 30 mg pamidronate once every three months for one year. These patients had been taking an average of 14 (range 7.5-40) mg prednisolone a day for an average of 14 (range 3-30) years. Bone density measurements, by dual energy x ray absorptiometry, and radiography of the dorsolumbar spine were carried out before and one year after treatment. Bone formation was assessed by measurement of serum alkaline phosphatase and bone resorption by measurement of the fasting urinary hydroxyproline: creatinine ratio at the same time as densitometry and radiography were performed.

RESULTS

Pretreatment density of L2-4 and the neck of the femur was significantly lower in these patients compared with a cohort of 100 age and sex matched controls (L2-4 (mean (SEM)): 0.906 (0.050) g/cm2 v 1.142 (0.016) g/cm2; neck of femur: 0.793 (0.030) g/cm2 v 0.936 (0.013)) g/cm2. After treatment there was a significant fall in serum alkaline phosphatase activity from (mean (SEM)) 220 (16) U/1 to 174 (9) U/1 (normal 80-280 U/1) and in the fasting urinary hydroxyproline:creatinine ratio from (mean (SEM) 0.040 (0.006) to 0.024 (0.003) (normal < 0.033). A significant rise was noted in L2-4 density to 0.927 (0.047) g/cm2; mean rise of 3.4%). No change was noted in density of the neck of the femur.

CONCLUSIONS

Intermittent infusions of intravenous pamidronate would seem to be effective in both reducing turnover of bone and increasing bone density in corticosteroid induced osteoporosis associated with chronic lung disease. Longer term controlled studies are indicated.

Pamidronate

OBJECTIVE

The primary objective of this article is to introduce readers to the use of a new agent, pamidronate. The article discusses its use in hypercalcemia of malignancy (HCM), osteolytic lesions, and Paget's disease. Pharmacokinetic data and clinical trials are reviewed, as well as adverse effects and dosage guidelines.

DATA SOURCES

A MEDLINE search was used to identify English-language studies involving pamidronate for the period from 1970 to 1992.

STUDY SELECTION

As comparative trials were few in number, trials using pamidronate as a single agent were also reviewed.

DATA EXTRACTION

Sparse pharmacokinetic data were obtained from clinical trials. All clinical trials available at the time of publication that met the following criteria were reviewed: (1) allowed for adequate rehydration prior to drug therapy; (2) reported standardized and corrected serum calcium concentrations; (3) separated data obtained from patients who received pamidronate alone from those who received pamidronate and concurrent chemotherapy.

RESULTS

Pamidronate has a pharmacologic profile similar to that of etidronate, but pamidronate is more potent and has a longer duration of effect. It has been investigated primarily in the treatment of HCM as well as in the treatment of osteolytic bone metastases and Paget's disease. In hypercalcemia of malignancy it appears to be as effective as established agents with the advantage that a single dose of pamidronate 90 mg iv provides a durable response. In Paget's disease chronic oral administration has also been shown to be effective in relieving bone pain. Adverse reactions with intravenous administration are transient and self-limiting and usually occur with the first dose. The most common adverse effect is a transient and self-limiting fever. Chronic oral administration of doses greater than 600 mg/d is associated with gastrointestinal toxicities.

CONCLUSIONS

Although more well-designed clinical trials comparing pamidronate with standard therapies and other available agents are necessary, initial results indicate that pamidronate is an effective and promising alternative for use in the treatment of HCM.

Medical management of hypercalcaemia

1. Hypercalcaemia is a common disorder, which frequently requires specific treatment either to control symptoms, or to prevent the development of irreversible organ damage or death. Although the best and most effective way of controlling hypercalcaemia in the long-term is to treat the underlying cause, medical antihypercalcaemic therapy is often required in clinical practice, either as a holding measure, or because the primary disease cannot itself be treated. 2. The mainstays of medical antihypercalcaemic therapy are firstly, to promote calcium excretion by the kidney by restoring extracellular volume with intravenous saline and secondly, to administer pharmacological agents which inhibit bone resorption. Measures which seek to reduce intestinal calcium absorption are seldom effective. 3. Intravenous bisphosphonates are the treatment of first choice for the initial management of hypercalcaemia, followed by continued oral, or repeated intravenous bisphosphonates to prevent relapse. These drugs have a relatively slow onset of action (1-3 days) but have potent and sustained inhibitory effects on bone resorption, resulting in a long duration of action (12-30 days). 4. Of the other agents available, calcitonin has an important place in the management of severe hypercalcaemia where a rapid effect is desirable; calcitonin is best used in conjunction with a bisphosphonate however, because of its short duration of action. Intravenous phosphate also has a place in the emergency management of severe hypercalcaemia, but is probably best reserved for patients in whom other less toxic therapies have failed. Corticosteroids are generally ineffective except in certain specific instances and are best avoided in the routine treatment of undiagnosed hypercalcaemia.

Bisphosphonates. Pharmacology and use in the treatment of tumour-induced hypercalcaemic and metastatic bone disease

The geminal bisphosphonates are a new class of drugs characterised by a P-C-P bond. Consequently, they are analogues of pyrophosphate, but are resistant to chemical and enzymatic hydrolysis. The bisphosphonates bind strongly to hydroxyapatite crystals and inhibit their formation and dissolution. This physicochemical effect leads in vivo to the prevention of soft tissue calcification and, in some instances, inhibition of normal calcification. The main effect is to inhibit bone resorption, but in contrast to the effect on mineralisation, the mechanism involved is cellular. These various effects vary greatly according to the structure of the individual bisphosphonate. The half-life of circulating bisphosphonates is very brief, in the order of minutes to hours. 20% to 50% of a given dose is taken up by the skeleton, the rest being excreted in the urine. The half-life in bone is far longer and depends upon the turnover rate of the skeleton itself. Bisphosphonates are very well tolerated; the relatively few adverse events that have been associated with their use are specific for each compound. Bisphosphonates have been used to treat various clinical conditions, namely ectopic calcification, ectopic bone formation, Paget's disease, osteoporosis and increased osteolysis of malignant origin. The three compounds commercially available for use in tumour-induced bone disease are in order of increasing potency, etidronate, clodronate and pamidronate. Most data have been obtained with the latter two agents. By inhibiting bone resorption, they correct hypercalcaemia and hypercalciuria, reduce pain, the occurrence of fractures, as well as the development of new osteolytic lesions, and in consequence improve the quality of life. In view of these actions, of their excellent tolerability and of the fact that they are active for relatively long periods, these compounds are, after rehydration, the drugs of choice in tumour-induced bone disease and an excellent auxiliary to the drugs used in oncology.

Clinical experience with pamidronate in the treatment of Paget's disease of bone

Bisphosphonates have been shown to be effective in treating the increased bone turnover associated with Paget's disease of bone. In this study two groups of patients were treated with pamidronate by intravenous infusion. In group 1 (n = 15) 30 mg of pamidronate was given once a week for six weeks. A subgroup (group 1A, n = 6) of more severely affected patients (pretreatment serum alkaline phosphatase (ALP) greater than 1000 U/l, normal range 80-280 U/l) received a further 60 mg weekly for three weeks. Group 2 (n = 24) received 45 mg of pamidronate every three months for one year. In both groups the level of ALP in serum samples decreased steadily throughout the year. In group 1 the level decreased to a mean value of 230 U/l (95% confidence interval 188-281) and in group 2 to 297 U/l (227-389). Four of the six patients in group 1A achieved normal ALP, whereas ALP remained at an increased level in all of the 10 patients in group 2 whose pretreatment ALP was greater than 1000 U/l, suggesting that a dose-response effect exists. The lowest hydroxyproline to creatinine ratios (normal ratio less than 0.033) were observed at the end of treatment in group 1, with a mean ratio of 0.022 (range 0.015-0.033) and at three months after the start of treatment in group 2 with a mean ratio of 0.029 (range 0.022-0.037). There was a significant decrease in the turnover of bone, as measured by whole body retention of radiolabelled bisphosphonate, from a mean of 49.3 to 41.0% (p less than 0.01). These data confirm that pamidronate is effective in the management of Paget's disease of bone. For patients with levels of ALP in serum samples of up to four times above the upper limit of the normal reference range, an effective and convenient regimen is 45 mg every three months for one year. For patients with higher levels of ALP higher doses may be more effective.