Fast (4-h) or slow (24-h) infusions of pamidronate disodium (aminohydroxypropylidene diphosphonate (APD)) as single shot treatment of hypercalcaemia

Bisphosphonates or RANK-ligand-inhibitors for men with prostate cancer and bone metastases: a network meta-analysis

BACKGROUND

Different bone-modifying agents like bisphosphonates and receptor activator of nuclear factor-kappa B ligand (RANKL)-inhibitors are used as supportive treatment in men with prostate cancer and bone metastases to prevent skeletal-related events (SREs). SREs such as pathologic fractures, spinal cord compression, surgery and radiotherapy to the bone, and hypercalcemia lead to morbidity, a poor performance status, and impaired quality of life. Efficacy and acceptability of the bone-targeted therapy is therefore of high relevance. Until now recommendations in guidelines on which bone-modifying agents should be used are rare and inconsistent.

OBJECTIVES

To assess the effects of bisphosphonates and RANKL-inhibitors as supportive treatment for prostate cancer patients with bone metastases and to generate a clinically meaningful treatment ranking according to their safety and efficacy using network meta-analysis.

SEARCH METHODS

We identified studies by electronically searching the bibliographic databases Cochrane Controlled Register of Trials (CENTRAL), MEDLINE, and Embase until 23 March 2020. We searched the Cochrane Library and various trial registries and screened abstracts of conference proceedings and reference lists of identified trials.

SELECTION CRITERIA

We included randomized controlled trials comparing different bisphosphonates and RANKL-inihibitors with each other or against no further treatment or placebo for men with prostate cancer and bone metastases. We included men with castration-restrictive and castration-sensitive prostate cancer and conducted subgroup analyses according to this criteria.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the quality of trials. We defined proportion of participants with pain response and the adverse events renal impairment and osteonecrosis of the jaw (ONJ) as the primary outcomes. Secondary outcomes were SREs in total and each separately (see above), mortality, quality of life, and further adverse events such as grade 3 to 4 adverse events, hypocalcemia, fatigue, diarrhea, and nausea. We conducted network meta-analysis and generated treatment rankings for all outcomes, except quality of life due to insufficient reporting on this outcome. We compiled ranking plots to compare single outcomes of efficacy against outcomes of acceptability of the bone-modifying agents. We assessed the certainty of the evidence for the main outcomes using the GRADE approach.

MAIN RESULTS

Twenty-five trials fulfilled our inclusion criteria. Twenty-one trials could be considered in the quantitative analysis, of which six bisphosphonates (zoledronic acid, risedronate, pamidronate, alendronate, etidronate, or clodronate) were compared with each other, the RANKL-inhibitor denosumab, or no treatment/placebo. By conducting network meta-analysis we were able to compare all of these reported agents directly and/or indirectly within the network for each outcome. In the abstract only the comparisons of zoledronic acid and denosumab against the main comparator (no treatment/placebo) are described for outcomes that were predefined as most relevant and that also appear in the 'Summary of findings' table. Other results, as well as results of subgroup analyses regarding castration status of participants, are displayed in the Results section of the full text. Treatment with zoledronic acid probably neither reduces nor increases the proportion of participants with pain response when compared to no treatment/placebo (risk ratio (RR) 1.46, 95% confidence interval (CI) 0.93 to 2.32; per 1000 participants 121 more (19 less to 349 more); moderate-certainty evidence; network based on 4 trials including 1013 participants). For this outcome none of the trials reported results for the comparison with denosumab. The adverse event renal impairment probably occurs more often when treated with zoledronic acid compared to treatment/placebo (RR 1.63, 95% CI 1.08 to 2.45; per 1000 participants 78 more (10 more to 180 more); moderate-certainty evidence; network based on 6 trials including 1769 participants). Results for denosumab could not be included for this outcome, since zero events cannot be considered in the network meta-analysis, therefore it does not appear in the ranking. Treatment with denosumab results in increased occurrence of the adverse event ONJ (RR 3.45, 95% CI 1.06 to 11.24; per 1000 participants 30 more (1 more to 125 more); high-certainty evidence; 4 trials, 3006 participants) compared to no treatment/placebo. When comparing zoledronic acid to no treatment/placebo, the confidence intervals include the possibility of benefit or harm, therefore treatment with zoledronic acid probably neither reduces nor increases ONJ (RR 1.88, 95% CI 0.73 to 4.87; per 1000 participants 11 more (3 less to 47 more); moderate-certainty evidence; network based on 4 trials including 3006 participants). Compared to no treatment/placebo, treatment with zoledronic acid (RR 0.84, 95% CI 0.72 to 0.97) and denosumab (RR 0.72, 95% CI 0.54 to 0.96) may result in a reduction of the total number of SREs (per 1000 participants 75 fewer (131 fewer to 14 fewer) and 131 fewer (215 fewer to 19 fewer); both low-certainty evidence; 12 trials, 5240 participants). Treatment with zoledronic acid and denosumab likely neither reduces nor increases mortality when compared to no treatment/placebo (zoledronic acid RR 0.90, 95% CI 0.80 to 1.01; per 1000 participants 48 fewer (97 fewer to 5 more); denosumab RR 0.93, 95% CI 0.77 to 1.11; per 1000 participants 34 fewer (111 fewer to 54 more); both moderate-certainty evidence; 13 trials, 5494 participants). Due to insufficient reporting, no network meta-analysis was possible for the outcome quality of life. One study with 1904 participants comparing zoledronic acid and denosumab showed that more zoledronic acid-treated participants than denosumab-treated participants experienced a greater than or equal to five-point decrease in Functional Assessment of Cancer Therapy-General total scores over a range of 18 months (average relative difference = 6.8%, range -9.4% to 14.6%) or worsening of cancer-related quality of life.

AUTHORS' CONCLUSIONS

When considering bone-modifying agents as supportive treatment, one has to balance between efficacy and acceptability. Results suggest that Zoledronic acid likely increases both the proportion of participants with pain response, and the proportion of participants experiencing adverse events However, more trials with head-to-head comparisons including all potential agents are needed to draw the whole picture and proof the results of this analysis.

Randomised study of single dose (8 Gy vs. 6 Gy) of analgesic radiotherapy plus zoledronic acid in patients with bone metastases

OBJECTIVE

To assess the effectiveness of a single dose of radio therapy (8 Gy vs. 6 Gy) plus zoledronic acid in cancer patients with bone metastases in treating pain; quality of life, time to onset of skeletal events and functional status.

MATERIAL AND METHODS

A total of 139 patients from 22 Spanish hospitals were randomly assigned to: Group A, administered a single dose of 8 Gy+zoledronic acid (4 mg iv, in 15-min infusions), and Group B, administered a single dose of 6 Gy+zoledronic acid (4 mg iv, in 15-min infusions). The main variable was pain, which was assessed with the Visual Analogue Pain Scale (VAS) in supine, seated and standing positions.

RESULTS

There was a total of 118 patients for intention to treat (n=67 in Group A and n=51 in Group B). The most frequent primary neoplasms were the lung (29.66%), prostate (22.03%) and breast (21.19%). Sixty patients were analysed per protocol, n=34 in group A and n=26 in group B. Improvements were observed in the VAS scores for pain in all three positions. The mean time to onset of the event was greater (p=0.0211) in Group A than in Group B (122 vs. 81.62 days). Functional status improved in Group A, and quality of life improved in both groups.

CONCLUSION

The two groups achieved similar levels of pain control in supine, seated and standing positions. Quality of life also improved in both groups. However, the higher dose (8 Gy dose) in combination with zoledronic acid is associated with a longer period without skeletal events.

Hyperparathyroid crisis: use of bisphosphonates as a bridge to parathyroidectomy

BACKGROUND

Hyperparathyroid crisis is an uncommon, potentially lethal condition for which emergent parathyroidectomy has been advocated.

STUDY DESIGN

The manifestations of hyperparathyroid crisis and outcomes of bisphosphonate-based therapy and delayed parathyroidectomy were determined and compared with cases from a review of the literature. Laboratory indices and gland weights were compared with those from patients with primary hyperparathyroidism without crisis.

RESULTS

Of the 292 patients operated on for hyperparathyroidism, 8 (2.8%) had hyperparathyroid crisis, consistent with rates of 1.6% to 6% reported in the literature. Hyperparathyroid crisis was manifested by vomiting, nausea, or both (n=6); abdominal pain (n=3); mental status changes (n=3); pancreatitis (n=2); bone pain, osteolytic lesions, or both (n=2); electrocardiogram changes (n=1); and an acute conversion disorder (n=1). Isotonic sodium chloride and furosemide, in combination with a bisphosphonate drug in 7 of 8 patients, resulted in a calcium decline from 16.2+/-1.6 mg/dL to 11.8+/-1.6 mg/dL, with resolution of electrocardiogram and mental status changes, and pancreatitis before resection of an adenoma (n=7) or carcinoma (n=1). Patients with hyperparathyroid crisis had higher parathyroid hormone levels (691.7 +/-662.4 pg/mL versus 172.6 +/-147.5 pg/mL; p=0.062), larger tumor weights (7.5 +/-8.4 g versus 1.6 +/-2.1 g; p=0.085), and lower postoperative calcium levels (7.3 +/-1.6 mg/dL versus 8.7+/-0.9 mg/dL; p=0.035) than patients without crisis. Four (50%) of the 8 tumors were found in ectopic locations. There was no mortality from hyperparathyroid crisis, compared with a 7% mortality rate for cases reported in the literature since 1978.

CONCLUSIONS

Rehydration, calciuresis, and bisphosphonate therapy are effective in correcting life-threatening manifestations of hyperparathyroid crisis, providing an effective bridge to parathyroidectomy.

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.

Systematic review of bisphosphonates for hypercalcaemia of malignancy

BACKGROUND

Bisphosphonates are the treatment of choice for hypercalcaemia of malignancy (HCM) but there is no consensus regarding which drug or dose should be given. We designed a systematic review to investigate the efficacy of bisphosphonates in the treatment of HCM.

METHODS

We identified randomized controlled trials (RCTs) by searching electronic databases, scanning of reference lists, and consultation with experts and pharmaceutical companies. Foreign papers were translated. Inclusion criteria were RCTs, confirmed malignant disease and measurement of serum calcium (ionized or corrected for albumin) postrehydration. The primary outcome was number of patients achieving normocalcaemia. Secondary outcomes were time to normocalcaemia, time to relapse and toxicity.

RESULTS

Twenty-seven papers and two abstracts, using intravenous bisphosphonates, fulfilled the inclusion criteria. Data from 26 studies were used in analyses. Due to the heterogeneity of studies, meta-analysis could not be performed. Pamidronate was more effective than placebo, mithramycin, etidronate (7.5 mg/kg) and low-dose clodronate (600 mg), but equal to higher dose clodronate (1500 mg). Clodronate and etidronate were superior to placebo; incadronate was superior to elcatonin; gallium nitrate was superior to etidronate. No difference was seen between alendronate and clodronate. Three dose finding studies showed no difference between 30-90 mg of pamidronate, but one well designed study showed increasing efficacy with increasing dose. Studies using increasing doses of ibandronate (0.6-4 mg), alendronate (2.5-15 mg), and incadronate (2.5-10mg), showed a dose response. Duration of administration of pamidronate did not affect efficacy (six studies).

CONCLUSION

Bisphosphonates normalize calcium in >70% patients with minimal side effects. Aminobisphosphonates are most effective at maintaining normocalcaemia and should be given in high dose irrespective of baseline serum calcium.

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

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

Relationship between physicochemical and osteotropic properties of bisphosphonic derivatives: rational design for osteotropic drug delivery system (ODDS)

PURPOSE

The objective of this investigation is to develop a rational design of Osteotropic Drug Delivery System (ODDS), which we have proposed as a novel method for drug delivery to the skeleton via bisphosphonic prodrug, based on the relationship between physicochemical and pharmacokinetic properties of bisphosphonates.

METHODS

The theoretical octanol/water partition coefficients (clog P) of 13 bisphosphonates were calculated by computer software, CLOGP ver. 3.05 (Daylight C.I.S., Inc. Irvine, CA) and related to pharmacokinetic or osteotropic parameters after intravenous injection into rats. On the other hand, to optimize ODDS of diclofenac (DIC-BP), the effects of doses or infusion rates on the in vivo disposition were investigated in relation to solubility product value (Ksp) of DIC-BP-calcium complex.

RESULTS

Clog P had good correlations with total plasma clearance, apparent distribution volume and the fraction dose delivered to the whole skeleton after bolus injection into rats (r = -0.868 approximately -0.914). The targetability of bisphosphonates to the skeleton was linearly decreased with an increase in clog P value and the more hydrophilic bisphosphonates were suitable for ODDS in bolus administration. On the other hand, DIC-BP, a relatively lipophilic bisphosphonate, was effectively and selectively delivered to the skeleton only when administered as a slow infusion to keep plasma concentration lower than that calculated from Ksp value where DIC-BP could precipitate with calcium in the plasma circulation.

CONCLUSIONS

Our results suggest the possibility of a rational design of ODDS via bisphosphonic prodrugs, after consideration of compound lipophilicity and precipitability of bisphosphonate-calcium complex.

Zoledronic acid reduces skeletal-related events in patients with osteolytic metastases

BACKGROUND

This study evaluated the dose-response relation for zoledronic acid, a new generation high potency bisphosphonate, given as a 5-minute infusion in patients with malignant osteolytic disease.

METHODS

Two-hundred eighty patients with osteolytic lesions due to metastatic breast carcinoma or multiple myeloma were randomized to double-blind treatment with either 0.4, 2.0, or 4.0 mg of zoledronic acid or 90 mg pamidronate. The primary efficacy endpoint was the proportion of patients receiving radiation to bone. Other skeletal-related events, bone mineral density (BMD), bone markers, Eastern Cooperative Oncology Group performance status, pain and analgesic scores, and safety also were evaluated.

RESULTS

Zoledronic acid at doses of 2.0 and 4.0 mg and pamidronate at a dose of 90 mg each significantly reduced the need for radiation therapy to bone (P < 0.05) in contrast with 0.4 mg zoledronic acid, which did not. Skeletal-related events of any kind, pathologic fractures, and hypercalcemia also occurred less frequently in patients treated with 2.0 or 4.0 mg zoledronic acid or pamidronate than with 0.4 mg zoledronic acid. Increases in lumbar spine BMD (6.2-9.6%) and decreases in the bone resorption marker N-telopeptide (range, -37.1 to -60.8%) were observed for all treatment groups. Skeletal pain, fatigue, nausea, vomiting, and headache were the most commonly reported adverse events. Adverse events were similar in nature and frequency with zoledronic acid and pamidronate.

CONCLUSIONS

A 5-minute infusion of 2.0-4.0 mg zoledronic acid was at least as effective as a 2-hour 90-mg pamidronate infusion in treatment of osteolytic metastases. A 0.4-mg dose of zoledronic acid was significantly less effective. Both zoledronic acid and pamidronate were well tolerated.

Zoledronic acid is superior to pamidronate in the treatment of hypercalcemia of malignancy: a pooled analysis of two randomized, controlled clinical trials

PURPOSE

Two identical, concurrent, parallel, multicenter, randomized, double-blind, double-dummy trials were conducted to compare the efficacy and safety of zoledronic acid and pamidronate for treating hypercalcemia of malignancy (HCM).

PATIENTS AND METHODS

Patients with moderate to severe HCM (corrected serum calcium [CSC] > or = 3.00 mmol/L [12.0 mg/dL]) were treated with a single dose of zoledronic acid (4 or 8 mg) via 5-minute infusion or pamidronate (90 mg) via 2-hour infusion. A protocol-specified pooled analysis of the two parallel trials was performed. Clinical end points included rate of complete response by day 10, response duration, and time to relapse.

RESULTS

Two hundred eighty-seven patients were randomized and evaluated for safety; 275 were evaluated for efficacy. Both doses of zoledronic acid were superior to pamidronate in the treatment of HCM. The complete response rates by day 10 were 88.4% (P = .002), 86.7% (P = .015), and 69.7% for zoledronic acid 4 mg and 8 mg and pamidronate 90 mg, respectively. Normalization of CSC occurred by day 4 in approximately 50% of patients treated with zoledronic acid and in only 33.3% of the pamidronate-treated patients. The median duration of complete response favored zoledronic acid 4 and 8 mg over pamidronate 90 mg with response durations of 32, 43, and 18 days, respectively.

CONCLUSION

Zoledronic acid is superior to pamidronate; 4 mg is the dose recommended for initial treatment of HCM and 8 mg for relapsed or refractory hypercalcemia.

A Phase I, open label, dose ranging trial of intravenous bolus zoledronic acid, a novel bisphosphonate, in cancer patients with metastatic bone disease

BACKGROUND

Bone metastases typically are associated with osteolytic bone destruction, resulting in bone pain, pathologic fractures, spinal cord compression, and hypercalcemia. Bisphosphonates are potent inhibitors of normal and pathologic bone resorption and represent a significant therapeutic improvement in the management of patients with lytic bone metastases. Zoledronic acid is a new-generation, highly potent, nitrogen-containing bisphosphonate that to the authors knowledge is the most potent inhibitor of bone resorption currently in clinical trials. The objectives of the current study were to assess the safety and tolerability of increasing doses of zoledronic acid and to determine its activity with respect to reducing biochemical markers of bone resorption in cancer patients with bone metastases.

METHODS

Forty-four cancer patients with bone metastases or primary bone lesions were enrolled sequentially into 1 of 5 fixed ascending-dose treatment groups. Each patient received a single intravenous bolus injection of 1, 2, 4, 8, or 16 mg of zoledronic acid over 30-60 seconds. Patients were monitored for 8 weeks for the evaluation of clinical findings, adverse events, vital signs, electrocardiograms, markers of bone resorption, and urinary N-acetyl-beta-D-glucosaminidase.

RESULTS

Zoledronic acid was safe and well tolerated at all dose levels tested. Commonly reported adverse events included bone pain, fever, anorexia, constipation, and nausea, which were experienced by a similar proportion of patients in each treatment group. Seven patients reported serious adverse events, none of which appeared to be related to the study drug. Zoledronic acid effectively suppressed biochemical markers of bone resorption, including the highly specific markers N-telopeptide and deoxypyridinoline, for up to 8 weeks in the 2-16-mg dose groups and for a shorter duration in the 1-mg group.

CONCLUSIONS

In the current study, zoledronic acid was safe and well tolerated and demonstrated potent inhibition of bone resorption. The authors believe it may improve the treatment of metastatic bone disease.

Pamidronate therapy as prevention of bone loss following renal transplantation

BACKGROUND

Very rapid bone loss, osteopenia and skeletal morbidity after renal transplantation have been well documented and found to occur in a sex dependent fashion. Glucocorticoids, cyclosporine and pre-existing uremic osteodystrophy have been implicated in the pathogenesis of the skeletal lesions. Glucocorticoid induced osteopenia is also a serious clinical problem in patients with various nonrenal diseases and can be prevented, or at least attenuated, by pamidronate and other bisphosphonates.

METHOD

We prospectively studied 26 male patients undergoing renal transplantation, and randomized them to receive either placebo or intravenous pamidronate (0.5 mg/kg) at the time of transplantation and again one month later. All patients received immunosuppression comprising prednisolone, cyclosporine and azathioprine. The bone mineral density (BMD) of the second, third and fourth lumbar vertebrae and of the femoral neck was measured at the time of transplantation and at three months and 12 months after transplantation using dual energy X-ray absorptiometry (DXA).

RESULTS

Twelve months after transplantation, the mean (+/- SEM) BMD of the lumbar vertebrae in patients who received placebo had decreased 6.4% (P < 0.05). In contrast, patients who received pamidronate experienced no significant reduction of BMD at the lumbar vertebrae. At the femoral neck, placebo-treated patients showed a reduction of BMD of 9% (P < 0.005), whereas there was no significant change in the pamidronate treated group. The two study groups had similar patient profiles, serum parathyroid hormone (PTH) and aluminium concentrations. After transplantation, comparable falls in the serum creatinine and PTH concentration were found in the two groups. Apart from transient hypocalcemia in two patients, no significant adverse effects of pamidronate were noted.

CONCLUSION

This study has shown that the early rapid bone loss that occurs in men during the first 12 months after renal transplantation can be prevented by two intravenous doses of pamidronate given at transplantation and one month later. The regimen was simple to administer, well tolerated and potentially applicable to other clinical groups of glucocorticoid treatment patients.

Acute management of cancer-related hypercalcemia

OBJECTIVE

To review the pathogenesis and pharmacologic treatment of acute hypercalcemia associated with malignancy.

DATA SOURCES

A MEDLINE search (1966 to 1995) of the English-language literature pertaining to acute hypercalcemia was performed. Additional literature was obtained from reference lists of articles identified through the search.

STUDY SELECTION AND DATA EXTRACTION

All articles discussing the etiology and medical management of cancer-related acute hypercalcemia were considered in this review. Clinical trials reporting efficacy and safety of antihypercalcemic agents were also included. Information selected in the review was based on the discretion of the authors.

DATA SYNTHESIS

Hypercalcemia is a life-threatening disorder associated with malignancy. It occurs in approximately 10-20% of patients with cancer. A variety of medications have been used in the management of hypercalcemia including bisphosphonates, calcitonin, furosemide, gallium nitrate, glucocorticoids, NaCl 0.9%, and plicamycin. Each of these agents has been reviewed with consideration of pharmacologic mechanism of action, evaluation of clinical trials, recommended dosages, efficacy, safety, cost, and role in treating cancer-related acute hypercalcemia.

CONCLUSIONS

Immediate management of cancer-related acute hypercalcemia to prevent death and provide symptomatic relief is warranted. Severity determined by symptoms, calcium concentrations, and the overall status of the patient are important considerations in selecting appropriate therapy. Although the specific role of individual agents may vary, hydration remains the cornerstone of therapy. NaCl 0.9%, calcitonin, and pamidronate disodium have established roles as dominant first-line agents for the management of acute hypercalcemia associated with malignancy.

The management of hypercalcemia of malignancy

Hypercalcemia (HCM) occurs in 10-15% of all malignancies, predominantly in patients with solid tumors. This metabolic complication leads to significant morbidity and impairment of quality of life. Recent insights into the pathophysiology of HCM include an understanding of the role of parathyroid-hormone-related peptide and several cytokines secreted by tumors. The osteoclast plays a central role as the final common pathway through which these hormones and cytokines act to cause bone lysis. These findings have led to the development of new treatment strategies. Foremost among these has been the introduction of agents such as the newer bisphosphonates and gallium nitrate, which are potent inhibitors of osteoclast-mediated bone resorption. The clinician can now choose from an array of therapeutic approaches based on a consideration of the mechanisms of action, individual clinical circumstances, efficacy, toxicities and costs of available agents. In addition to their use in the management of HCM, non-toxic drugs that effectively inhibit osteoclast function, such as the bisphosphonates, are playing an emerging role in the palliative treatment of the more common clinical problems of painful lytic bone metastases and osteoporosis.

Drugs used in the treatment of metabolic bone disease. Clinical pharmacology and therapeutic use

Osteoporosis is the most important metabolic bone disease and places an increasing burden on the healthcare system. The condition can be prevented by the early introduction of hormone replacement therapy. The role of bisphosphonates in achieving the same result is being actively explored. The attraction of preventing bone loss is that it preserves the micro-architecture of bone, and therefore its mechanical integrity. The great problem of treating the established condition is that substantial bone loss is accompanied by architectural disintegration. Replacing lost bone may not necessarily restore mechanical integrity and protect against fractures. The management of Paget's disease has been quite revolutionised by the introduction of the bisphosphonates. The condition is a result of a primary increase in osteoclastic bone resorption which can be corrected by bisphosphonates, with considerable symptomatic improvement. The increasing potency and safety margin of the newer agents has meant that the threshold for treatment has fallen. There is now potential for long term control of bone turnover with the hope of preventing late complications. Hypercalcaemia of malignancy is usually the result of both increased bone destruction and decreased urinary calcium excretion. These two components of hypercalcaemia demand different approaches to management. The general availability of an ever-expanding range of increasingly potent bisphosphonates has resulted in a dramatic improvement in the treatment of increased bone resorption associated with malignancy. Many types of tumour, either directly or indirectly, compromise the ability of the kidney to eliminate a calcium load derived from increased bone destruction. Calcitonin is the only agent which is currently available to counter this process.

Newer agents for the treatment of malignant hypercalcemia

The treatment of malignant hypercalcemia has involved fluids, diuretics, and specific calcium-lowering therapy with mithramycin and calcitonin. However, newer agents have recently been approved for the treatment of hypercalcemia due to malignancy. This review will discuss three such agents, gallium, etidronate, and pamidronate. This review will concentrate on the clinical pharmacologic characteristics and the clinical trials of these newer agents. Their use in the clinical practice will be suggested based on review of the published literature.

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.

Comparison of a rapid (2-h) versus a slow (24-h) infusion of alendronate in the treatment of hypercalcemia of malignancy

Alendronate (aminohydroxybutylidene bisphosphonate) is a potent inhibitor of bone resorption but the role of the duration of intravenous infusion in its efficacy profile is unclear. In a two-centre, parallel, randomized, double-blind study, 20 patients with tumoral hypercalcemia received a single 10-mg i.v. infusion over either 2 h (group A, n = 10) or 24 h (group B, n = 10). Recurrences (n = 6) were retreated using the same regimen. Pretreatment plasma calcium (Ca) was 3.32 +/- 0.08 mM (mean +/- SEM) for all patients. Treatment A and B were associated with similar temporal profiles for onset, time to reach normocalcemia, (6 vs 5 days), nadir (day 6: 2.45 +/- 0.06 vs 2.43 +/- 0.08 mM) and time to relapse (day 21). Normocalcemia (2.15-2.55 mM) was achieved in seven (A) and nine (B) patients with other cases being partial responders (Ca: 2.65-2.76 mM). A significant decrease of urinary calcium and hydroxyproline excretion and a significant increase of PTH accompanied Ca normalization in both groups. Ca response was 50% lower on 2nd treatment with alendronate. Both treatments were well tolerated with transient mild fever being the most common adverse experience. In conclusion, whether infused over 2 or over 24 h, a single dose of 10 mg alendronate led to normalization of tumoral hypercalcemia in a large majority of cases.

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.