Effects of intravenous etidronate disodium on skeletal and calcium metabolism

Bisphosphonates: biological response modifiers in breast cancer

Bone recurrence constitutes one third of initial sites of relapse and one half of distant sites of relapse at 10 years from diagnosis of breast cancer. Bone pain, fracture (including vertebral fracture resulting from increased bone resorption following chemotherapy-induced menopause), and hypercalcemia are components of skeletal morbidity. The pathophysiology of malignant osteopathy occurs because of the secretion of substances (such as parathyroid hormone-related peptide), by the malignant cell, which stimulate osteoclast function; this in turn feeds further growth, which causes a vicious cycle. Interruption of this cycle by bisphosphonates may inhibit the growth of malignant cells. Bisphosphonates are drugs that inhibit bone turnover by decreasing bone resorption. Side effects of bisphosphonates include upper gastrointestinal symptoms (in oral nitrogen-containing bisphosphonates) and diarrhea (in oral non-nitrogen-containing bisphosphonates) and an acute phase-like reaction with intravenous (I.V.) pamidronate. Bisphosphonates have different molecular mechanisms of action: Nitrogen-containing bisphosphonates (eg, pamidronate and alendronate) inhibit the mevalonate-signaling pathway while the non-nitrogen-containing drugs (eg, clodronate) incorporate into adenosine triphosphate analogues. There is in vitro evidence that these drugs also possess anticancer properties. In hypercalcemia patients, treatment with pamidronate and zoledronate produce prompt and efficient normocalcemia. Intravenous pamidronate and zoledronate, oral clodronate, and ibandronate reduce skeletal complications in patients with bone metastases; I.V. pamidronate and clodronate are useful for bone pain relief. Three adjuvant bisphosphonate trials are discussed herein: 2 small open-label studies giving conflicting results and a large placebo-controlled trial of oral clodronate. This latter trial shows a reduction in the incidence of skeletal metastases (while the patients are on therapy) and an improved survival at 5 years.

Direct effects of bisphosphonates on breast cancer cells

In addition to inhibiting bone resorption, bisphosphonates have also been shown to exhibit antitumour effects. In vitro, bisphosphonates inhibit proliferation and induce apoptosis in cultured human breast cancer cells. In addition, bisphosphonate treatment interferes with breast cancer cell adhesion to bone matrix, and inhibits cell migration and invasion. The combination of bisphosphonates with other anticancer drugs such as the taxoids markedly enhances these effects. These newly recognized direct actions of bisphosphonates on breast cancer cells indicate that these agents may have a greater role to play in treatment of patients suffering from cancers with a propensity to metastasize to bone.

Bisphosphonates in multiple myeloma

BACKGROUND

Myelomatosis is associated with considerable skeletal morbidity, particularly bone pain and fractures. Hypercalcaemia is a common presenting feature but less common after adequate chemotherapy. These complications are caused by progressive focal and generalized osteolysis due, in turn, to increased activation of osteoclasts by osteoclast activating factors. These include tumor necrosis factor-beta, interleukin-1, and interleukin-6. The knowledge that disturbed bone remodeling is due to the activation of authentic osteoclasts provides the rationale for the use of bisphosphonates in myelomatosis.

METHODS

This article reviews the place of bisphosphonates in the management of myeloma.

RESULTS

There is good evidence that hypercalcaemia can be corrected with intravenous or oral bisphosphonates, and they are now the specific treatment of choice. Several studies have shown that their intravenous administration is beneficial in the acute management of bone pain due to malignancy, but studies in myelomatosis are lacking. In contrast, a number of well designed controlled studies have shown significant effects of long term treatment with clodronate and pamidronate to decrease the incidence of skeletal complications in myelomatosis. Benefits reported are a decreased incidence of bone pain, hypercalcaemia, vertebral and long-bone fractures, and the extension of osteolytic lesions. There may be a beneficial effect on survival, but this is much less certain.

CONCLUSIONS

These agents provide a valuable adjunct to the management of myelomatosis.

Bisphosphonates induce apoptosis in human breast cancer cell lines

Breast cancer has a prodigious capacity to metastasize to bone. In women with advanced breast cancer and bone metastases, bisphosphonates reduce the incidence of hypercalcaemia and skeletal morbidity. Recent clinical findings suggest that some bisphosphonates reduce the tumour burden in bone with a consequent increase in survival, raising the possibility that bisphosphonates may have a direct effect on breast cancer cells. We have investigated the in vitro effects of bisphosphonates zoledronate, pamidronate, clodronate and EB 1053 on growth, viability and induction of apoptosis in three human breast cancer cell lines (MDA-MB-231, Hs 578T and MCF-7). Cell growth was monitored by crystal violet dye assay, and cell viability was quantitated by MTS dye reduction. Induction of apoptosis was determined by identification of morphological features of apoptosis using time-lapse videomicroscopy, identifying morphological changes in nucleis using Hoechst staining, quantitation of DNA fragmentation, level of expression of bcl-2 and bax proteins and identification of the proteolytic cleavage of Poly (ADP)-ribose polymerase (PARP). All four bisphosphonates significantly reduced cell viability in all three cell lines. Zoledronate was the most potent bisphosphonate with IC50 values of 15, 20 and 3 microM respectively in MDA-MB-231, MCF-7 and Hs 578T cells. Corresponding values for pamidronate were 40, 35 and 25 microM, whereas clodronate and EB 1053 were more than two orders of magnitude less potent. An increase in the proportion of cells having morphological features characteristic of apoptosis, characteristic apoptotic changes in the nucleus, time-dependent increase in the percentage of fragmented chromosomal DNA, down-regulation in bcl-2 protein and proteolytic cleavage of PARP, all indicate that bisphosphonates have direct anti-tumour effects on human breast cancer cells.

Hypercalcemia and hypermagnesemia

Hypercalcemia and hypermagnesemia occur infrequently in small animal patients. Specific clinical signs usually do not accompany these electrolyte disorders, and their presence is often recognized only after reviewing serum chemistry profile results. The etiologies, clinical signs, and therapies for each electrolyte disorder are discussed in this article. Treatment of these disorders is aimed at correcting the underlying disease process and enhancing the removal of calcium or magnesium from the body. In severe cases, rescue therapies and resuscitative measures are required to stabilize the patient.

Renal tolerability profile of novel, potent bisphosphonates in two short-term rat models

Bisphosphonates are used clinically to inhibit bone resorption but they may also cause renal damage. For the profiling of new potent bisphosphonates, their adverse renal effects were investigated in 2 rat models. In the first model, bisphosphonate was repeatedly injected (1 mg/kg, subcutaneously) over 2 weeks and the urinary excretion of malate dehydrogenase was monitored to assess nephrotoxic potential. Of the 6 new compounds tested, 3 markedly elevated malate dehydrogenase whereas 3 others caused only minor changes similar to those observed with 6 reference bisphosphonates that are already used clinically. On the basis of a therapeutic index (inhibition of bone resorption versus renal effects) 7-180 fold greater than that of other analogues, the compound CGP 42446 was further profiled. In the second model, CGP 42446 or pamidronate was infused (1.5-50 mg/kg, intravenously) into anaesthetized rats and the serum urea concentration was monitored as an indicator of renal dysfunction. Both compounds elevated serum urea in a time- and dose-dependent manner, but the ED100 value for CGP 42446 was 3.8-fold higher than that of pamidronate. It is concluded that CGP 42446 (zoledronate) has a low nephrotoxic potential and can be further developed as a new potent inhibitor of bone resorption.

Comparison of three intravenous regimens of clodronate in Paget disease of bone

We compared the effects of three different regimens of intravenous clodronate in a retrospective study of 60 patients with Paget disease. A total dose of 1500 mg of clodronate was given as 300 mg for 5 consecutive days (n = 20), 1500 mg as a single infusion (n = 20), or 300 mg as a single infusion for 5 consecutive months (n = 20). The response to treatment and the duration of the effect were assessed from sequential changes in the activity of serum alkaline phosphatase. Treatment with clodronate induced a significant response in 85% of patients. The response rate was comparable in patients treated with 5 daily infusions (90%), with a single infusion (75%), and with 5 monthly infusions (90%). The median duration of response from the start of treatment was 11 months for those treated with five daily infusions and 12 months for the other two regimens. At one year, 22, 40, and 44% of patients had maintained their response in the daily, single, and monthly infusion regimen, respectively (NS). Six patients (32%) treated with 5 daily infusions achieved a remission (complete response) compared with 3 patients treated with a single infusion and 5 monthly infusions, respectively (16 and 15% respectively, NS). Patients attaining a complete response had a significantly longer duration of response compared with partial responders (median time 15.0 versus 11.5 months, respectively, p < 0.05). We conclude that intravenous clodronate (total dose 1500 mg) suppresses disease activity in the majority of patients with Paget disease of bone. The degree and duration of response were similar for the three regimens. Thus, in the treatment of Paget disease, the choice of regimen is a matter of convenience.

The effects of intravenous alendronate in Paget's disease of bone

We studied the effects of intravenous alendronate on disease activity in 36 patients with active Paget's disease of bone. Alendronate was administered to 3 groups of 12 patients at doses of 2.5, 5, and 10 mg intravenously daily for 5 consecutive days. The patients were matched for disease activity. Symptomatic improvement was seen in at least 10 patients in each treatment group. Alendronate induced a dose-dependent suppression of biochemical indices of bone turnover in all patients. A significant reduction in the mean fasting urinary excretion of hydroxyproline occurred within 2 days of starting treatment, reaching a nadir at 2-4 weeks, which was most marked in patients receiving 10 mg of alendronate (p < 0.05). There was a slower fall in serum alkaline phosphatase activity with maximal suppression occurring 3 months after the start of treatment. The degree of suppression was least for those receiving 2.5 mg of alendronate (p < 0.05) but no difference in response was observed for the other dosages. The duration of response was also dose-related. A significant fall in the serum calcium and urinary excretion of calcium occurred from the second day of treatment but returned to pretreatment values by 4 months. A transient fall in the mean lymphocyte count was observed, which was similar for each group. This was associated with a short-lived fever in 3 patients receiving 10 mg, in 4 patients receiving 5 mg, and in 2 patients receiving 2.5 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Clodronate and other bisphosphonates as supportive therapy in osteolysis due to malignancy

Clodronate, one of the most investigated bisphosphonates, has been clinically utilised for over 10 years in malignancy. It is the most used, most effective and safest drug in the treatment of hypercalcaemia. It inhibits lytic bone destruction, prevents bone fractures and relieves bone pain. Supportive clodronate therapy may even reduce hypercalcaemia mortality and the morbidity caused by osteolysis. These results have stimulated studies on the patients' quality of life. New methods for the measurement of bone resorption, such as the degradation product of type I collagen (ICTP), may improve the possibility of monitoring the effect of clodronate. Comparative studies with different bisphosphonates in hypercalcaemia and long-term controlled trials using bisphosphonates as supportive therapy in osteolysis due to malignancy are reviewed.

Etidronic acid. A review of its pharmacological properties and therapeutic efficacy in resorptive bone disease

Etidronic acid is an orally and intravenously active bisphosphonate, which is believed to inhibit resorption of bone via a number of cellular mechanisms, including alteration of osteoclastic activity. In studies of patients with symptomatic Paget's disease, etidronic acid 5 to 20 mg/kg/day administered orally rapidly decreased the biochemical indices of bone turnover. Mineralisation defects in forming bone may be avoided by the use of an initial dosage of 5 mg/kg/day for up to 6 months; dosages above 10 mg/kg/day should be limited to 3 months' duration, and dosages greater than 20 mg/kg/day should be avoided. Although 3-day intravenous therapy with etidronic acid 7.5 mg/kg/day has shown superior efficacy to rehydration and forced diuresis in the management of hypercalcaemia of malignancy, the efficacy of the drug is lower than that of the newer bisphosphonates, pamidronic acid and clodronic acid. Clinical studies involving postmenopausal women with established osteoporosis have indicated that oral etidronic acid 400 mg/day for 14 days as part of a 90-day cycle, repeated for up to 3 years, increases the bone mineral density (BMD) of the lumbar vertebrae and appears to reduce the incidence of vertebral fracture. Published data suggest that etidronic acid shows similar efficacy to hormone replacement therapy (HRT) in these respects. The above dosage also appears to be effective in preventing corticosteroid-induced osteoporosis when administered as part of an intermittent, cyclical regimen. Etidronic acid in higher dosages (10 to 20 mg/kg/day orally) is effective in reducing the incidence of heterotopic ossification and its ensuing complications in both neurological and post-surgical patients. Etidronic acid is well tolerated by the majority of patients, with gastrointestinal complaints reported most commonly, but tends to delay the normal mineralisation of forming bone when administered continuously at higher dosages for prolonged periods. This is of little consequence where short term treatment is involved, but may be detrimental to those patients receiving longer courses of therapy. This effect may be minimised or avoided by using the lowest effective dosage for as short a time as possible (as in the above recommendations for Paget's disease), or by the use of intermittent cyclical therapy (as in the management of osteoporosis). Etidronic acid therefore retains a role in the management of resorptive bone disease, particularly in the treatment of Paget's disease, the prevention of heterotopic ossification, and as a second-line option in postmenopausal osteoporosis. However, the development of newer bisphosphonates requires that these compounds be continually compared and re-evaluated.

The effect of alendronate on renal tubular reabsorption of phosphate

We report the effects of alendronate on phosphate homeostasis in two patients. In a woman with postmenopausal osteoporosis, the infusion of alendronate (7.5 mg intravenously daily for 4 consecutive days) was not associated with secondary hyperparathyroidism despite a reduction in serum calcium. This was associated with a rise in serum phosphate and TmP/GFR. This response contrasted with those observed in 14 other patients with osteoporosis, in whom PTH rose significantly following the infusion of alendronate in association with a significant fall in serum phosphate and TmP/GFR. The second patient, a woman with Paget's disease, was treated with intravenous alendronate (10 mg daily for 5 consecutive days) on two occasions for relapse of disease activity. On the first occasion there was a 150% rise in serum PTH associated with a fall in serum phosphate and TmP/GFR. On the second occasion, when the rise in serum PTH was less marked, there was a rise in serum phosphate and TmP/GFR. We conclude that alendronate may increase renal tubular reabsorption of phosphate, but that this effect is usually offset by secondary hyperparathyroidism.

Tumour induced hypercalcaemia: a case for active treatment

This paper reports a retrospective survey of the diagnosis, management and outcome of hypercalcaemia in patients admitted to a regional oncology centre over a 12-month period; 168 cases of tumour induced hypercalcaemia were identified. In 69 patients (41%) the presence of hypercalcaemia was not noted in the case records; in a further 15 patients (9%) a positive decision was made not to treat the condition, although some of these patients continued to receive other forms of active treatment. Of the remaining patients, 20 (12%) received intravenous fluids alone and 64 (38%) received bisphosphonate therapy. Of those patients with initial serum calcium > 3 mmol/l 71% were treated with bisphosphonates. Median survival from onset of hypercalcaemia was only 2 months, but in the bisphosphonate treated group, 98% experienced a fall in serum calcium within a week of treatment. We believe that the symptomatic relief associated with a fall in serum calcium justifies active management even in the face of a poor prognosis. A large proportion of cases of tumour induced hypercalcaemia remain undiagnosed or untreated and we believe that this deserves further attention.

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.

Intravenous disodium etidronate therapy in spinal cord injury patients with heterotopic ossification

The goal of the present study was to use intravenous etidronate in the acute phase of heterotopic ossification (HO) in an attempt to achieve a high initial drug concentration at the site of the active ectopic ossification. The study included 27 consecutive patients with an acute onset of HO after spinal cord injury (SCI). The three-phase bone scan was used to confirm clinical diagnosis of HO. Disodium etidronate (Didronel) 300 mg was administered intravenously daily for 3 to 5 days. In 20 patients there was a rapid (1-2 days) decrease of soft tissue swelling (p < 0.01) with no side effects associated with the intravenous administration. In seven patients there was minimal or no improvement of edema after intravenous etidronate. In these patients deep vein thrombosis was found in the affected limbs. The effect of high dose etidronate on HO was determined in the group of 13 patients with positive clinical and scintigraphic finding of an acute HO, but negative radiographic studies. After intravenous administration of etidronate for 3 days (300 mg/day) the drug was continued orally with 20 mg/kg/day for 6 months. A placebo was not used in this study. In eight patients there was no radiographic evidence of HO after therapy while two patients had minimal ossifications. In three patients therapy was interrupted and all developed HO in 1-2 months.

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.

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.

Paget's disease of bone treated with a five day course of oral tiludronate

Chloro-4-phenyl thiomethylene bisphosphonate (tiludronate) is a new drug which can be used as an inhibitor of bone resorption. As it remains in bone for a long time, and as mineralisation defects have only been seen at doses much higher than those required to decrease osteoclastic activity, it could be given at high doses over a short period of time. Eighteen patients with Paget's disease of bone were randomly allocated to three therapeutic groups receiving respectively 600, 800, and 1200 mg/day tiludronate for five days. Serum alkaline phosphatase activity and the urinary hydroxyproline/creatinine ratio were quickly and drastically reduced in all three groups. A significant reduction of serum alkaline phosphatases and the hydroxyproline/creatinine ratio was still present six months after the five day therapeutic course, reflecting a sustained activity of tiludronate even after stopping treatment. Dose dependent short and long term reductions of bone turnover rate were observed. Biochemical assessment of haematological, renal, or hepatic tolerance did not show any toxicity of tiludronate. Fifty per cent of patients treated by a dose of 1200 mg/day reported gastrointestinal disturbances, however, making this dosage unsuitable for clinical practice.

Role of bisphosphonates in metabolic bone diseases

Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption and represent the treatment of choice in disorders associated with accelerated bone resorption. They are widely used in the management of Paget's disease of bone and hypercalcemia of malignancy. Over the past few years, evidence has been accumulating for a beneficial effect of these agents in tumor-induced osteolytic bone disease and in established osteoporosis. Bisphosphonates may also play a useful though limited role in the medical management of hyperparathyroidism and heterotopic ossification.

Comparative effects of clodronate and calcitonin on bone in metastatic breast cancer: a histomorphometric study

We studied the effects of long-term treatment with clodronate, calcitonin or placebo on bone in 36 normocalcaemic women with osteolytic metastases due to breast cancer. Clodronate (1.6 g daily given to 12 patients) induced a significant decrease in osteoclast surface and osteoclast number, and a significant fall in serum calcium and urinary excretion of calcium and hydroxyproline, an effect not noted after treatment with calcitonin (100 U in 12 patients) or in 12 placebo-treated patients. Treatment with clodronate did not abnormally suppress bone turnover nor impair mineralisation, as measured by bone formation and mineral apposition rates.

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.

Effect of salmon calcitonin and etidronate on hypercalcemia of malignancy

Hypercalcemia of malignancy is a commonly encountered serious clinical problem that often requires aggressive therapy. In order to combine the rapid hypocalcemic effects of calcitonin with the more delayed effect of a bisphosphonate, we administered etidronate, 7.5 mg/kg/day intravenously and salmon calcitonin, 100 IU subcutaneously, every 12 hours for 3 days in 9 patients with hypercalcemia associated with malignancy. The mean serum calcium concentration fell from 3.33 +/- 0.1 mmol/liter (mean +/- SEM) to 2.88 +/- 0.1 mmol/liter within 24 hours (P less than 0.001). All patients had a fall in the serum calcium concentration of greater than 0.5 mmol/liter and it returned to normal in 7 of the 9 patients. We conclude that the combination of salmon calcitonin with etidronate more effectively lowers the serum calcium concentration in patients with hypercalcemia of malignancy then the use of either agent alone.

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.

Spontaneous quinolone resistance in Serratia marcescens due to a mutation in gyrA

Spontaneous quinolone-resistant mutants of MP050, a quinolone-susceptible clinical strain of Serratia marcescens, were isolated on nutrient agar containing 0.5 microgram of ciprofloxacin per ml. One mutant, designated MP051, was selected for further study. Quinolone MICs for MP051 were 4- to 16-fold higher than those for MP050; nonquinolone MICs were unchanged. The DNA gyrase isolated from MP051 was 24-fold less sensitive to inhibition of supercoiling by ciprofloxacin than the DNA gyrase isolated from MP050 was. Inhibition studies on reconstituted combinations of heterologous gyrase subunits showed that the decreased inhibition was dependent on the A subunit of DNA gyrase from MP051. Further evidence that this decreased inhibition was due to a gyrA mutation was provided by analysis of Escherichia coli gyrA gene expression in S. marcescens heterodiploids containing pNJR3-2, a broad-host-range gyrA gene probe. Quinolone susceptibilities of MP051 heterodiploids containing the wild-type E. coli gyrA gene decreased to those of MP050, while quinolone susceptibilities of MP050 containing the same plasmid were unchanged. These results indicate that spontaneous quinolone resistance in MP051 was due to a mutation in gyrA.

Effects of amino-butylidene diphosphonate in hypercalcemia due to malignancy

We studied the effect of a single 5 mg intravenous infusion of amino-butylidene diphosphonate (ABDP) in nine patients with hypercalcemia of malignancy, in whom serum calcium values were stable or rising after intravascular volume expansion. Serum calcium fell progressively in all patients and in seven reached the normal reference range by day 6 (p less than 0.001). The decrease in serum calcium was associated with a decrease in the fasting urinary calcium/creatinine ratio (p less than 0.05). Hypercalcemia recurred in seven of the patients by day 12, but two patients remained normocalcemic for 21 days. We conclude that ABDP is a highly potent diphosphonate and that a single intravenous infusion is capable of inhibiting tumour-mediated bone resorption for several days.

Treatment of Paget's disease of bone with aminohydroxybutylidene bisphosphonate

This study examined the effects of aminohydroxybutylidene bisphosphonate in 30 patients with Paget's disease of bone, administered as an intravenous infusion for 5 consecutive days. Treatment (5 mg IV daily) induced marked suppression of biochemical indices of disease activity. Urinary excretion of hydroxyproline fell to 50% of pretreatment values within 2 weeks and was followed by a similar, but later, decline in the serum activity of alkaline phosphatase. Disease activity remained suppressed throughout the 6 months of observation, and only 1 patients showed biochemical signs of an early relapse. Symptomatic improvement was noted in 27 of the 30 patients. Bone biopsies, undertaken in 10 patients, indicated no adverse effects on mineralization. Transient falls were noted in the total white cell count, particularly the lymphocyte and neutrophil fractions, and were associated with short-lived fever in 3 patients. We conclude that short courses of intravenous AHButBP provide a promising treatment for active Paget's disease of bone.

Comparison of three intravenous bisphosphonates in cancer-associated hypercalcaemia

Three intravenous bisphosphonates were compared in the treatment of cancer-associated hypercalcaemia. 48 patients were randomly allocated to one of three treatment groups (each with 16 subjects)--30 mg pamidronate or 600 mg clodronate, both as single intravenous infusions; or etidronate as three infusions of 7.5 mg/kg per day for three consecutive days. Patients were rehydrated with normal saline before bisphosphonate treatment. All three bisphosphonates lowered serum calcium by inhibiting bone resorption; pamidronate was the most potent in this respect. By comparison with the other groups, more patients in the pamidronate group became normocalcaemic, and the effect on serum calcium was apparent sooner and lasted longer.

Treatment of tumor hypercalcemia with clodronate

In an open, controlled study 34 patients with tumor hypercalcemia of different origin were treated with clodronate. The initial dosage was 300 mg intravenously daily. After achieving normocalcemia, treatment was continued orally using 400-3200 mg/day depending on serum calcium concentration. Most patients showed normocalcemia within 1 week of treatment - only few of them needed a longer time. Fifteen of 34 patients died within the observation time of up to 24 weeks, some being normocalcemic. However, a reincrease in plasma calcium during treatment was an indicator of deterioration. Measurements of plasma parathyroid hormone (PTH) using an intact molecule radioimmunometric assay showed depressed levels before clodronate treatment started, but PTH rose after achieving normal and especially low normal calcium levels. Starting 1,25-dihydroxycholecalciferol [1,25(OH)2D3] values were decreased or in the lower normal range in the majority of patients, but in 6/21 patients plasma 1,25(OH)2D3 was in the upper normal range or elevated despite hypercalcemia. After lowering plasma calcium the 1,25(OH)2D3 levels increased. However, there was no significant correlation between PTH and 1,25(OH)2D3. Therefore we assume that in some patients additional stimulation of renal 1 alpha-hydroxylase by tumor products is present.

Paget's disease of bone

Paget's disease is a relatively common bone disease. This review aims to present reasonable treatment recommendations with enough background to understand them. To accomplish this end, some aspects of basic bone cell biology, biochemistry, and pathology are presented, as are speculations about possible causes of this disease. Treatment of Paget's disease will be considered in three sections. The first two sections will review treatment with calcitonin and diphosphonates, respectively. These sections briefly will consider the mechanism of action of the drugs, review in detail clinical studies of drug effectiveness, and summarize the advantages and disadvantages of each drug. The third section details specific treatment recommendations for each of the six clinical settings in which treatment of Paget's disease is justified.

Bone and renal components in hypercalcemia of malignancy and responses to a single infusion of clodronate

Increased bone resorption (BR) and increased renal tubular reabsorption of calcium (TRCa) may both be involved in the pathogenesis of hypercalcemia of malignancy (HM). We have evaluated the relative importance of these two mechanisms in 33 patients with HM after extracellular volume expansion and after single infusion of clodronate (C12MDP: 500 mg iv over 8 h). The fasting urine Ca/creatinine ratio was taken as an index of BR (BRI). An index of TRCa was calculated (TRCaI) from a nomogram based on the relationship between urine Ca excretion per unit of glomerular filtration rate and plasma Ca (PCa). Mean (+/- SEM) PCa fell from 3.29 +/- 0.07 to 2.69 +/- 0.05 mmol/l three days after C12MDP (n = 33, p less than 0.001), a response similar to that obtained with repeated daily iv injections of 500 to 1000 mg C12MDP. The pathogenesis of hypercalcemia varied according to the type of neoplasm. BRI was the highest in multiple myeloma and breast tumors. TRCaI was markedly increased in squamous-cells lung, bladder, kidney and liver carcinomas, reaching levels observed in primary hyperparathyroidism. TRCaI was normal in most cases of multiple myeloma. Breast tumors appeared to be heterogeneous with respect to TRCaI. The fall in PCa in response to a single infusion of C12MDP was usually most marked in cancer patients with elevated BRI and normal TRCaI. It was very modest in patients with high TRCaI and slightly elevated BRI. In conclusion, this study confirms that stimulation of bone resorption is not the only mechanism of the maintenance of hypercalcemia of malignancy.(ABSTRACT TRUNCATED AT 250 WORDS)