APD in Paget's disease of bone. Role of the mononuclear phagocyte system?

A comparison of low versus high dose pamidronate in cancer-associated hypercalcaemia

Pamidronate has been demonstrated to be an effective agent in the treatment of cancer-associated hypercalcaemia. The dose regime, however, remains controversial. In this study 16 patients with cancer-associated hypercalcaemia were given 30 mg pamidronate by intravenous infusion and 16 were given 90 mg also by infusion. Groups were well-matched in terms of tumour types, bone metastases, pre-treatment serum calcium and creatinine, fasting urinary calcium/creatinine ratio, nephrogenous cAMP and the renal tubular threshold for phosphate reabsorption (TmPO4). The calcium lowering effect was similar in both treatment groups with nadir at day 6 of mean (+/- SEM) 2.48 mmol/l (+/- 0.06) in the 30 mg group and at day 9 in the 90 mg group of 2.51 mmol/l (+/- 0.03) (P less than 0.01). 10 patients in the 30 mg group and 8 in the 90 mg group were normocalcaemic at this point. Similarly when those patients with more severe hypercalcaemia (greater than 3.30 mmol/l, n = 7 in each group) were analysed separately, no significant difference was evident between the two groups. Urinary calcium/creatinine ratios fell to a nadir at day 6 in both groups of 0.33 (+/- 0.05) (30 mg group) and 0.37 (+/- 0.10) (90 mg group) (P less than 0.01). Follow-up results after the initial 9 days showed the mean time to relapse to be 38 days (range 18-90) in the 30 mg group and 34 days (11-105) in the 90 mg group.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of clodronate and pamidronate on splenic and hepatic phagocytic cells of mice

Bisphosphonates inhibit the activity of osteoclasts and conceivably also macrophage activity. Administered in hypoosmotic solution, clodronate (dichloromethylene bisphosphonate) forms complexes with the iron of haemolysed erythrocytes and subsequently accumulates in splenic and hepatic macrophages. Pamidronate (3-amino-1-hydroxypropylidene bisphosphonate) also accumulates in the spleen and liver of mice and rats even when injected in isoosmotic solution. In the present study, the effects in mice of uncomplexed clodronate, clodronate-iron complex, clodronate-liposomes, and pamidronate on splenic and hepatic macrophages in vivo were studied by an enzyme-histochemical method. Intracellular free clodronate released in the cells after phagocytosis of clodronate-liposomes virtually eliminated all macrophages from spleen, and also Kuppfer cells from liver. Clodronate given in hypoosmotic vehicle had no effect on these cells, although it was taken up by them. Clodronate in isoosmotic vehicle, considered as uncomplexed clodronate, neither accumulates in nor affects the macrophages. Pamidronate, however, decreased the number of the cells also after isoosmotic injection. Thus, the capability of bisphosphonates to sequestrate intracellular calcium may explain their effects on macrophages.

Intravenous aminobisphosphonate in Paget's disease: clinical, biochemical, histomorphometric and radiological responses

Intravenous 3-amino-1-hydroxypropylidene-1, 1-bisphosphonic acid (APD) was used to treat 26 patients with Paget's disease. Three daily dosages were studied; 20-30 mg/day in 20 patients, 45 mg/day in three patients and 60 mg/day in three patients, by daily 4-hour infusions for 2-10 days. The fasting urinary hydroxyproline excretion (HypE) declined exponentially, reaching 50% of pretreatment values at 1.92 +/- 0.16 (mean +/- SEM) days. This initial rapid decline was complete by 4 days following treatment to a mean of 28.0 +/- 3.4% of pretreatment values. Thereafter, there was no significant decline in HypE. The initial rate of decline of HypE was unchanged by increasing the daily dose of APD. Transient non-symptomatic hypocalcaemia with secondary hyperparathyroidism occurred in all patients. No adverse changes in the renal handling of calcium or phosphate, as seen with high-dose 1-hydroxyethylidene-1, 1-bisphosphonate (EHDP), were seen in any patient on any daily dose. Fever occurred in 73% of patients in the first 2 days of treatment. Overall, there was a significant fall in the lymphocyte count (P less than 0.005 febrile group, n = 19; P less than 0.02 non-febrile group, n = 7) and a fever-dependent rise in the neutrophil count (P less than 0.005 febrile group only). The occurrence of fever was associated with a more rapid decline in HypE, compared to the non-febrile group, so that HypE was significantly lower in the febrile group by day 5 (P less than 0.025). Seventy-two per cent of patients with bone and/or joint pain reported a reduction in pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition by a new bisphosphonate (AHBuBP) of bone resorption induced by the MBT-2 tumor of mice

A new bisphosphonate, 4-amino-1-hydroxybuthylidene-1,1-bisphosphonate (AHBuBP), was compared with 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (AHPrBP) and 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) in terms of its effect on tumor-induced osteolysis using a bladder tumor in mice (MBT-2). Tumor cells were inoculated subcutaneously (SC) over the calvaria in mice, resulting in a local tumor causing fragmentation of the bone. The tumor-induced osteolysis associated with osteoclasts proliferation was accompanied with reactive new bone formation. This osteolysis was evaluated by measuring the increased area of bone resorption in reduced opacity to radiograph and histologic study. The results showed the following sequence of potency: AHBuBP greater than AHPrBP = HEBP. This inhibition was obtained with no apparent effect on the growth of the MBT-2 tumor. The authors conclude that AHBuBP appears to be an interesting new bisphosphonate with possible clinical application.

Disposition and nephrotoxicity of 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD), in rats and mice

The purpose of this study was to investigate the disposition and the nephrotoxicity of 3-amino-1-hydroxypropylidene-1, 1-bisphosphonate (APD-pamidronate) in order to elucidate the mechanism of the non-linearity of the renal elimination of this drug. The fate of APD labelled with [14C]APD was studied in mice and rats for a range of doses (0.5-40 mg/kg) and indicators of renal function were monitored. In both species, the percentage of dose excreted during the first 24-h after treatment fell dramatically as a function of the dose. However, the renal burden of APD rose linearly for doses of APD below 10 mg/kg and increased non-linearly over this threshold. In contrast the concentration of APD in both bone and liver, which together account for a large proportion of the dose, appeared to increase proportionally with dose. There was no evidence, therefore, that the non-linear renal elimination of APD was due to an increased uptake of APD by tissues. Conversely, the significant fall in the renal excretion of APD was paralleled by a striking loss in body weight, and for high doses, by a fall in the creatinine clearance. An increased enzymuria suggested the loss of brush border membranes and the release of lysosomal contents by proximal tubular cells. Morphological studies confirmed this and revealed a focal proximal tubular necrosis 6 days post dosing. We conclude that the nephrotoxicity of APD accounts for the non-linear renal elimination of this drug.

Bisphosphonates in vitro specifically inhibit, among the hematopoietic series, the development of the mouse mononuclear phagocyte lineage

Bisphosphonates (BP) are powerful inhibitors of bone resorption. We have previously shown that 4-amino-1-hydroxybutylidene-1,1-bisphosphonate (AHBuBP), 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (AHPrBP), and dichloromethylenebisphosphonate (Cl2MBP) inhibit the proliferation of macrophages in vitro at concentrations that do not affect the viability of nonproliferating cells. In this study we further investigated whether the antiproliferative effect of these three BP is, among the hematopoietic series, preferential to the mononuclear phagocyte lineage. BP were unable to inhibit more than 30-40% of the [3H]thymidine (3H-TdR) incorporation into bone marrow cells stimulated to proliferate by multilineage colony-stimulating activity containing conditioned medium (multi-CSA). From the analysis of the colonies induced in semisolid medium by multi-CSA and recombinant murine granulocyte-macrophage colony stimulating factor (rmGM-CSF), a dose-dependent disappearance specific to the macrophage-containing colonies emerged. In contrast, the number and composition of colonies other than macrophage and, in particular, the granulocyte colonies were not affected by these compounds, even at high concentrations (100 microM) previously also shown to be toxic for nonproliferating macrophages. Since the macrophages, differently from polymorphonuclear phagocytes, are known to be highly pinocytotic, it is possible that by this means they selectively concentrate BP intracellularly, leading to toxic concentrations. We postulate tht BP may also act in vivo in addition to their effect on osteoclast activity, by a similar mechanism on osteoclast precursors and on bone resident macrophages, a source of cytokines stimulating bone resorption and leading to impaired osteoclast recruitment and activity.(ABSTRACT TRUNCATED AT 250 WORDS)

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 the distribution of three bisphosphonates in mice

The distribution of approximately equipotent doses of 14C-labelled clodronate (0.1 mmol/kg), etidronate (0.1 mmol/kg), and amidronate (0.015 mmol/kg), and also an equimolar dose of amidronate (0.1 mmol/kg), was studied in mice by measuring the 14C-activities in various tissues up to 360 days after a single intravenous injection. With the higher dose of amidronate the distribution could be, however, monitored only for 7 days because of the toxicity of the drug. The results indicate that there are major differences in the deposition of the bisphosphonates into soft tissues, while the disappearance from plasma and incorporation into bone are quite similar in terms of percentage of dose per g of tissue. However, the binding capacity of bone for clodronate and etidronate is many times greater than that for amidronate expressed as nmol of the drug per g of tissue. Amidronate deposits in the spleen and liver of mice, when injected in saline, whereas clodronate and etidronate do not. This agrees with the suggestion that amidronate, but not the other two, can interfere with the mononuclear phagocyte system of spleen and liver.

Effects of phosphonoformic and phosphonoacetic acids on developing enamel of rat molars

The effect of a single subcutaneous injection of different dosages of phosphonoformic or phosphonoacetic acid on the developing dental tissues of the rat molar was studied. The substances were injected at different rat ages and effects on the developing teeth were analyzed by means of histochemistry of frozen sections and scanning electron microscopy. Molars of rats injected at the age of 10 or 15 days showed no pathologic changes. Administration of phosphonoacetic acid in a dosage of 10 or 20 mg P/kg b.w. had no demonstrable effect on the dental tissues in any of the animals. Phosphonoformic or phosphonoacetic acid in a dosage of 10 or 30 mg P/kg b.w. respectively induced subameloblastic cysts 24 h after injection to 4-7-day-old rats. The cysts were mainly localized on the mesial sides of the cusps under ameloblasts in the late secretory stage. Calcified depositions were seen in the ameloblastic layer lining the cystic cavities. A thin zone, the staining of which indicated a high mineral content, was seen in the outermost enamel layer under the cysts. A few days later, enamel hypoplasias were seen in areas previously occupied by cysts. A lightly stained line was observed in the enamel matrix demarcating the amount of enamel matrix formed before and after the injection. Hypoplastic lesions were also noted in the enamel surface of newly erupted molars. These findings suggest that the two injected monophosphonates can induce pathologic changes in the developing enamel organ and hypoplasias in the enamel.

Bisphosphonates: a new class of drugs in diseases of bone and calcium metabolism

The geminal bisphosphonates are characterized by a PCP bond and are therefore analogs of pyrophosphate. They bind strongly to hydroxyapatite crystals and in vitro inhibit both crystal formation and dissolution. In vivo they inhibit soft tissue calcification and when given in large amounts also normal calcification. This effect is due to the inhibition of calcium phosphate crystal growth. Furthermore, the bisphosphonates are very potent inhibitors of bone resorption. The mechanism(s) of action is not yet known but is likely to be at a cellular level. The extent of the biological activity of each compound depends on the specific chemical structure, so that each individual bisphosphonate must be considered as a separate compound. The only common characteristic is the PCP group, which gives the compound its high affinity to bone. The individual effects, however, are determined by the side groups on the carbon atom. This opens interesting possibilities for the development of new compounds. No bisphosphonate analyzed so far can be degraded in vivo; all are either deposited in the skeleton, where they remain for years until the bone is destroyed, or are excreted in the urine. The high affinity for bone explains the specificity of the compounds for bone and the fact that they have relatively few nonosseous effects. Bisphosphonates are used in man to inhibit ectopic calcification, including dental tartar and ectopic ossification. Furthermore, they are used to inhibit bone resorption, especially in diseases such as Paget's disease and tumoral osteolysis. Finally, when linked to 99nTc, bisphosphonates are employed as bone scanning agents.

Relapse of osteoporosis circumscripta as a lytic ring after treatment of Paget's disease with intravenous 3-amino-1-hydroxypropylidene-1,1-bisphosphonate

Two patients with osteoporosis circumscripta of the skull are presented who have each been treated with a 3-month course of intravenous infusions of (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) (total dose of 185 and 375 mg), which in both cases was associated with rapid and dramatic remineralization of the porotic bone and marked clinical and biochemical remission. However, osteolytic disease reappeared (after 9 and 18 months, respectively) in both cases as an osteolytic ring showing high uptake of radiolabelled bisphosphonate on bone scan, in formerly unaffected bone just distal to the original leading edge of osteolysis. Further treatment was associated with healing of these new lesions. These cases suggest that the diseased osteoclasts entering previously normal bone are protected against the drug probably because normal bone matrix takes up relatively little APD, and that APD taken up by diseased bone behind this front confers long-term resistance to further resorption. In assessing treatment strategies with bisphosphonates for Paget's disease, the response at the leading edge of osteoporosis circumscripta may be particularly informative.

A single infusion of the bisphosphonate AHPrBP (APD) as treatment of Paget's disease of bone

PURPOSE

Disabling pain, skeletal deformity, or risk of joint involvement characterize Paget's disease of bone. Because the disease often affects the elderly, for whom compliance is a problem, we investigated therapy with a single intravenous infusion of amino-hydroxypropylidene bisphosphonate (AHPrBP, previously APD).

PATIENTS AND METHODS

Eleven patients with mild but symptomatic Paget's disease and one patient with very severe disease were treated with AHPrBP administered as a single intravenous infusion of 60 mg over 24 hours. Follow-up with clinical and biochemical evaluations was performed over six months for all patients, and over one year for seven patients.

RESULTS

Clinical improvement and normalization of biochemical parameters were observed in all patients except one with extremely severe disease. On average, plasma alkaline phosphatase activity fell progressively and significantly from 256 +/- 29 U/liter (mean +/- SEM) to 97 +/- 6 U/liter after six months, and to 102 +/- 11 U/liter after one year (normal: less than 120 U/liter). Urinary excretion of hydroxyproline decreased within seven days to normal (from 4.3 +/- 0.5 mumol/liter of glomerular filtrate [lGF] to 1.7 +/- 0.2 mumol/lGF; normal: 2.2 mumol/lGF). Thereafter, it remained within the normal range until one year (1.8 +/- 0.2 mumol/lGF after six months and 1.9 +/- 0.3 mumol/lGF after one year). Side effects were negligible. Two patients noted only a transient increase in body temperature. When bone scintigraphy was repeated after six months, it revealed a marked decrease of the activity of the disease.

CONCLUSION

Due to the important and sustained inhibition of bone resorption induced by AHPrBP, a single infusion of 60 mg of the bisphosphonate leads to a rapid decline in activity and a long-standing remission of moderate Paget's disease, without significant side effects.

Aminobisphosphonate inhibition of interleukin-1-induced bone resorption in mouse calvariae

Interleukin-1 (IL-1) is probably an important lymphokine mediator of inflammation and bone resorption. IL-1 derived from mononuclear cells, a melanoma cell line (MM96 cells), and recombinant human IL-1 (rHuIL-1 beta) increased in vitro bone resorption, as measured by the release of 45Ca from cultured mouse calvariae. The 50% maximum active resorption was observed with 0.125 ng/ml or approximately 10(-11) M rHuIL-1 beta. The resorptive action of IL-1 was not entirely dependent on prostaglandin mediation, since its effect was evident when prostaglandin synthesis was inhibited in the cultures by indomethacin. IL-1-induced resorption has been shown to be inhibited by 10(-5) M 3-amino-1-hydroxypropylidene-1-1-bisphosphonate (APD). This inhibition was partially reversed by increasing doses of IL-1. In vitro toxicity studies showed that at concentrations of 10(-4) M, APD inhibited the growth of cultured MM96, murine myelomonocytic P388D1, and rat osteosarcoma UMR 106 cells, but not other mast and lymphoid cell lines. These in vitro observations may have relevance to the use of APD in bone and joint diseases in which inflammation and bone resorption are prominent.

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.

The acute-phase response after bisphosphonate administration

In patients who have never previously received bisphosphonate therapy, the intravenous administration of 4-amino-1-hydroxybuthilidene-1,1-bisphosphonate (AHButBP), 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (AHPrBP), or 6-amino-1-hydroxyhexylidene-1,1-bisphosphonate (AHHexBP) induced an acute-phase response (APR) irrespective of the underlying disease, manifested by a fall in circulating lymphocyte number and serum zinc concentration and in a rise in C-reactive protein (CRP); a febrile reaction occurred in 30% of the patients. The APR was maximally expressed within 28-36 hours of i.v. administration of the bisphosphonates and disappeared 2-3 days later despite continuous treatment. These effects were dose dependent and the lowest doses necessary for an APR were 10 mg of AHButBP and AHPrBP and 75 mg of AHHexBP. Doses up to 1,000 mg/day i.v. of dichloromethanebisphosphonate (Cl2MBP) were devoid of these side effects. In patients treated with either a single i.v. dose of amino-bisphosphonates which resulted in an APR or with a suboptimal dose, a subsequent challenge 12-160 days later of the high dose failed to cause a rise in CRP or a fall in the lymphocyte count. The desensitization to AHButBP or AHPrBP was also seen following pretreatment with Cl2MBP. These findings suggest that bisphosphonates interact with macrophage-like cells resident in the skeleton and stimulate interleukin-1 release which is responsible for the appearance of the APR. At the same time, however, the bisphosphonates render these cells insensitive to further stimulation for several months.(ABSTRACT TRUNCATED AT 250 WORDS)

Paget's disease of bone: early and late responses to three different modes of treatment with aminohydroxypropylidene bisphosphonate (APD)

Early and late responses to treatment with either oral (600 mg/day) or intravenous (20 mg/day) (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (aminohydroxypropylidene bisphosphonate; APD) were studied in 142 patients with Paget's disease of bone who had not previously been treated with bisphosphonate. The efficacy of three therapeutic regimens was compared: (a) oral aminohydroxypropylidene bisphosphonate given continuously until six months after the serum alkaline phosphatase activity had returned to normal (long term); (b) oral aminohydroxypropylidene bisphosphonate given until urinary hydroxyproline excretion had returned to normal (short term); (c) intravenous aminohydroxypropylidene bisphosphonate for 10 days. With either oral or intravenous treatment the decrease in urinary hydroxyproline excretion was rapid and always preceded the fall in serum alkaline phosphatase activity. Normal urinary hydroxyproline excretion is essential for return of the serum alkaline phosphatase activity to normal. Complete biochemical remission, defined as return of the serum alkaline phosphatase activity to normal, was obtained in 129 patients (91%). The median duration of remission as assessed by actuarial analysis was 2.7 years. This study found no difference in the long term among the three modes of treatment, suggesting that for most patients with Paget's disease a short course of intravenous aminohydroxypropylidene bisphosphonate will produce longlasting, complete remission without need for maintenance treatment.

Radiological assessment of Paget's disease of bone after treatment with the bisphosphonates EHDP and APD

The effects of therapy on the osteolytic bone lesions of Paget's disease have been assessed from serial bone radiographs. Changes in the rate of progression of lytic "wedge" lesions were measured and alterations in the texture of lytic "blade" lesions were graded on an empirical scale. Useful matching was possible using standard radiographs, although special care was needed to avoid artefacts from suboptimal positioning, magnification and variation in exposure. Serial radiographs were obtained of 57 lytic blade lesions in 54 patients receiving treatment with the bisphosphonate 1-hydroxyethylidene-1, 1-bisphosphonate (EHDP) and of 20 lesions in 20 patients treated with oral or intravenous 3-amino-1-hydroxypropylidene-1, 1-bisphosphonate (APD). Treatment with EHDP was associated with a significant deterioration in bone texture in 50% of lytic blade lesions, and with healing in only 20%. Deterioration was accompanied by an increase in local bone pain in 17% of these patients. In contrast, significant healing was observed in 17 of 20 lytic lesions (eight wedge, nine blade) within 6 months of beginning a course of intravenous or oral APD. In four of eight patients the progression of a lytic tibial wedge was arrested and in the remaining four the direction of wedge movement was reversed. In two patients the wedge had almost completely "filled in", making measurement difficult. Bone healing was usually accompanied by pain relief, reduction in skin temperature and rapid suppression of the urine hydroxyproline (uHP) into the normal range. However, in four patients who received intravenous APD, repair of lytic bone lesions was observed despite persisting elevation of uHP. These improvements with APD were sustained at 12 months, although in one patient whose biochemical indices were restored to normal the resorption front showed further progression, despite initial temporary reversal. The trends apparent in these short-term studies were also seen in four patients in whom wedge velocities were measured over periods of 6-10 years. These results confirm that after treatment of Paget's disease, bone healing or deterioration can be accurately assessed from serial standard radiographs. Reproducible matching is best achieved by ensuring that all radiographs are taken by the same radiographer. Minor alterations in radiological bone texture provide an important index of drug effect which is not always apparent from measurement of biochemical and other indices.

A comparison of single and multiple intravenous infusions of 3-amino-1-hydroxypropylidene-1, 1-bisphosphonate (APD) in the treatment of hypercalcemia of malignancy

Following rehydration with intravenous saline, 27 patients with hypercalcemia of malignancy were treated with a total of 32 courses of 3-amino-1-hydroxypropylidene-1, 1-bisphosphonate (APD) given by slow intravenous infusion. Twelve treatments consisted of daily infusions of APD for between two and six days whereas single-dose APD was used in 20 treatments. Mean albumin-adjusted serum calcium fell to the upper end of the reference range at seven days from the start of treatment, both in multiple-dose and in single-dose treatment groups. No relationship between total dose of APD and hypocalcemic response was observed. However, second treatments with APD following recurrence of hypercalcemia in five patients were significantly less effective than the original therapy, suggesting that resistance to APD may develop. Multiple-dose and single-dose intravenous APD treatments appear to be equally effective in the acute management of hypercalcemia of malignancy.

Effect of bisphosphonates on proliferation and viability of mouse bone marrow-derived macrophages

Bisphosphonates (BP) are powerful inhibitors of bone resorption. Their mechanism of action, although still unclear, is now believed to be at the cellular level. In this study we investigated the effects of these compounds on proliferation, induced either by L-cell conditioned medium (CSF-1) or 4-phorbol 12-myristate 13-acetate (PMA) of bone marrow cells (BMC) and on CSF-1-induced proliferation and viability of bone marrow derived macrophages (BMDM phi). BMC proliferation, measured by [3H]-TdR incorporation or by clonal assay in soft agar, was significantly inhibited by 4-amino-1-hydroxybutylidene-1,1-bisphosphonate (AHBuBP) and 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (AHPrBP) at 2.5 x 10(-7) M and by dichloromethylenebisphosphonate (Cl2MBP) at 2.5 x 10(-6) M. This inhibitory effect was also confirmed on the proliferation, measured by [3H]-TdR incorporation, of BMDM phi. In the absence of CSF-1, the viability of this latter cell population, estimated by DNA content per well and lactate dehydrogenase (LDH) released into the medium, was affected in the following order of concentrations: Cl2MBP, 1.0 x 10(-4) M; AHBuBP, 5.0 x 10(-5) M; and AHPrBP, 2.5 x 10(-5) M. Since osteoclasts and macrophages might share a common early progenitor cell, probably under the control of CSF-1, the effect exerted by BP on the proliferation of the macrophage precursors may also be extended to the osteoclast precursors.

Efficacy of aminohydroxypropylidene diphosphonate in the treatment of malignancy-associated hypercalcaemia

Two patients with symptomatic malignancy-associated hypercalcaemia were treated with intravenously-administered aminohydroxypropylidene diphosphonate (APD). Both patients demonstrated dramatic falls in serum calcium concentration, and in urinary calcium and hydroxyproline excretion that were consistent with a reduction in the rate of bone resorption. Normocalcaemia occurred by day 5 and persisted for approximately three weeks after treatment. No significant side-effects were encountered. It was concluded that APD is a promising new agent in the management of hypercalcaemia that is associated with malignant disease and warrants further investigation.

Different schedules of administration of (3 amino-1-hydroxypropylidene)-1, 1 bisphosphonate induce different changes in pig bone remodeling

Intermittent administration of antiosteoclastic agents has been proposed in order to increase trabecular bone volume (TBV). We evaluated the effect of two different intermittent schedules of administration of (3 amino-1-hydroxypropylidene)-1, 1 bisphosphonate (AHPrBP) on pig bone remodeling for a period of 60 days. AHPrBP (1.6 mumol/kg/injection) was given subcutaneously daily (group A1), or 5 consecutive days out of 21 days (group A2), or 1 out of every fourth day (group A3). Compared to control animals, group A1 significantly increased trabecular bone volume (TBV) (+62%) with a marked decrease in bone resorption assessed by interstitial bone thickness. Bone formation assessed by mean wall thickness (MWT) was also decreased due to a decrease in the number and activity of osteoblasts. There was not a delay in the coupling mechanism as assessed by the reversal surfaces. The two groups receiving intermittent schedules had markedly different results. Group A2 had very similar changes to group A1 despite receiving four time less drug. Compared to group A1 and A2, group A3 had smaller decrease in resorption and higher bone formation rate with identical MWT. These differences between group A2 and A3 were associated with similar levels of parathyroid hormone and vitamin D metabolites. Different bone concentrations induced by the two different schedules of AHPrBP may explain the greater effect on bone resorption and osteoblast recruitment in group A2 and thus a milder effect of the AHPrBP administration once every fourth day.

Effects of intravenous etidronate disodium on skeletal and calcium metabolism

The induction of hypercalcemia in malignant disease is almost invariably associated with increased bone resorption. However, tumor-induced changes in bone formation and renal tubular resorption of calcium are also important factors that induce hypercalcemia in some patients. In addition, alterations in calcium fluxes to and from the extracellular fluid secondary to hypercalcemia are important in maintaining or aggravating the hypercalcemic effects of increased bone resorption. These factors significantly affect the responses to treatment of hypercalcemia with inhibitors of bone resorption. This study examined the relative importance of these factors and the effects of intravenous etidronate disodium (etidronate) in neoplastic bone disease with and without hypercalcemia and in Paget's disease of bone. It is concluded that intravenous etidronate is an effective inhibitor of bone resorption, which accounts in large measure for its effects on serum calcium concentrations. These studies of etidronate in hypercalcemia suggest the response is sustained for several weeks.

Paget's disease of bone treated in five days with AHPrBP (APD) per Os

Amino-hydroxypropylidene bisphosphonic acid (AHPrBP, previously APD) is a potent inhibitor of bone resorption. Since it remains in bone for a long time, and since it was not found to impair bone mineralization, it could be administered at high dose over a short period of time. Therefore, 11 patients with symptomatic Paget's disease received AHPrBP orally at 1200 mg/day over 5 consecutive days. Controls were performed after 1 month in all patients, 6 months in 8 patients, and one year in 4 patients. Clinical improvement and biochemical remission was observed in all patients, except one with severe disease. Side effects were negligible. Disease activity at bone scintigram decreased over 6 months. Plasma alkaline phosphatase activity fell progressively and significantly from 210 +/- 26 U/l (means +/- SEM) to 103 +/- 10 U/l after 6 months (nl less than 120 U/l). Urinary excretion of hydroxyproline decreased immediately and became normal (nl less than 2.3 mumol/lGF) as a mean at day 5 (from 4.6 +/- 0.4 mumol/lGF to 2.1 +/- 0.3 mumol/lGF). Thereafter it remained within the normal range (2.0 +/- 0.2 mumol/l at day 180). Plasma calcium and phosphate concentrations fell transiently between day 4 and 15, whereas plasma PTH levels increased over this period of time. In conclusion, a short course of AHPrBP given per os at high dose induces a rapid decline in activity and remission of moderate Paget's disease, without significant side effects.

Effects of four bisphosphonates on bone resorption, lysosomal enzyme release, protein synthesis and mitotic activities in mouse calvarial bones in vitro

The effects of 3-amino-1-hydroxy-propylidene-1,1-bisphosphonate (AHPrBP), 1-hydroxyethylidene-1,1-bisphosphonate (HEBP), dichloromethylenebisphosphonate (Cl2MBP) and azacycloheptylidene-2,2-bisphosphonate (AHBP) on bone were examined in organ culture using newborn mice calvaria. AHPrBP, HEBP and Cl2MBP caused a dose-dependent inhibition of PTH-stimulated (10 nmol/l) release of 45Ca from the calvaria, at and above a concentration of 3 mumol/l, whereas AHBP only caused a slight inhibition, at and above 100 mumol/l. AHPrBP inhibited PTH-stimulated release of 3H from bones prelabelled with [3H]-proline. AHPrBP (30 mumol/l) diminished the stimulatory effect of 1 alpha(OH)vitamin D3 (10 nmol/l), prostaglandin E2 (0.1 mumol/l) and renal tumor conditioned media on 45Ca release. AHPrBP and Cl2MBP, at and above 3 mumol/l, decreased PTH-stimulated mobilization of Ca2+ and Pi and in parallel the release of beta-glucuronidase without affecting the release of lactate dehydrogenase. The inhibitory effect of AHPrBP (30 mumol/l) on PTH-induced 45Ca release was irreversible. The inhibition by AHPrBP (30 mumol/l) on spontaneous and PTH-stimulated release of 45Ca can be seen first after 24 h of culture. Similarly the inhibitory effect by HEBP (30 mumol/l) and Cl2MBP (30 mumol/l) was delayed and could be observed after 36 and 24 h of culture, respectively. PTH-stimulated release of Ca2+, Pi, beta-glucuronidase and beta-N-acetylglucosaminidase was reduced by AHPrBP first after 24 h of culture. AHPrBP, HEBP and Cl2MBP, at concentrations which are inhibitory on bone resorption, do not affect protein synthesis and mitotic activities in mouse calvaria. These data show that AHPrBP, HEBP and Cl2MBP inhibit bone resorption in vitro and in parallel decrease lysosomal enzyme release by a mechanism, which is not related to cytotoxicity. In addition, the delayed inhibitory effect on bone resorption and lysosomal enzyme release by all the compounds suggest that bisphosphonates inhibit bone resorption indirectly and not by a direct effect on existing osteoclasts. The delayed inhibition by bisphosphonates on bone resorption may be due to decreased recruitment of new osteoclasts as a consequence of an inhibitory action on mononuclear osteoclast precursor cells.

The effect of anti-rheumatic drugs on factors from porcine synovium inducing chondrocyte mediated cartilage degradation

A selection of NSAID's and diphosphonates were studied in a tissue culture model of cartilage degradation utilising porcine synovium and bovine nasal cartilage. All the NSAID's significantly reduced cartilage degradation when incorporated into the synovial culture medium. Lesser reductions were recorded when preformed chondrocyte stimulating factors were used and NSAID's added at the cartilage assay stage. These findings suggested that the principle site of action of NSAID's is upon the production of chondrocyte stimulating factors. None of the NSAID's tested affected inherent cartilage degradation. Diphosphonates had the opposite effects, they increased inherent cartilage degradation but had no effect on chondrocyte mediated cartilage degradation. The relationship of these results to previous known effects of NSAID's and diphosphonates upon cartilage is discussed. In addition, correlations between chondrocyte stimulating factors, catabolin and interleukin 1 are made.

Treatment of Paget's disease of bone with intravenous 4-amino-1-hydroxybutylidene-1,1-bisphosphonate

4-amino-1-hydroxybutylidene-1,1-bisphosphonate (AHButBP) was given intravenously (2.5-25 mg/day for 4 days) to 14 patients with Paget's disease of bone, five of whom had been treated with dichloromethylidene bisphosphonate (C12MBP) 32 months earlier. In the nine patients who had not been treated previously with bisphosphonates, the short course of AHButBP induced a suppression of serum alkaline phosphatase and urinary hydroxyproline values down to 30% of initial values. The biochemical suppression of the disease was sustained for 2-18 months and the time to relapse did correlate to the logarithm of the dose (P less than 0.001). In the five patients previously treated for Paget's disease, an apparent resistance to treatment with AHButBP was observed. However, in these patients both serum alkaline phosphatase and urinary hydroxyproline fell to or even below the nadir values which had previously been achieved with C12MBP, irrespective of the degree of relapse. Thus the degree of suppression of Paget's disease of bone, achievable after treatment with bisphosphonates, seems to be constant for each patient, such that normal levels of serum alkaline phosphatase and urinary hydroxyproline cannot usually be attained in patients with extremely active disease.

Studies on the chronic phase of adjuvant arthritis: effect of SR 41319, a new diphosphonate

We studied the course of adjuvant arthritis in rats by measuring clinical, biochemical, and histological parameters on day 36 after induction (representing the secondary reaction) and on day 171, which is at the stage of permanent deformity. The effect of SR 41319, a new diphosphonate, was evaluated on days 36 and 171, after three weeks of treatment (days 14-35 inclusive). In the absence of treatment all the measured parameters were markedly abnormal on day 36, indicating the presence of lesions that were still evolving. On day 171 clinical parameters and the lesion histological index remained the same, whereas the biochemical parameters and disease activity histological index had returned to normal, indicating that the lesions at this stage although severe were not inflammatory and consequently not progressing. SR 41319 treatment reduced the severity and progression of the disease both on day 36 and on day 171. We conclude that SR 41319 may be a potentially useful drug for the treatment of rheumatoid arthritis.

Quantitative bone scintigraphy in Paget's disease treated with APD

Half-yearly bone scintigrams of 27 patients with Paget's disease, who were treated with the bisphosphonate APD, were evaluated. Uptake of 99Tcm-Sn-EHDP was determined by computer analysis. All patients reached clinical and biochemical remission, usually within 6 months. The scintigraphic uptake dropped steeply during the first 6 months and only slightly during the second 6 months. The decrease in uptake was proportional to the original uptake and averaged 80% of this value. The residual 20% persisted, although clinical and biochemical remission were attained. The scintigraphic results obtained with APD agree with our earlier findings for patients in remission after treatment with a combination of calcitonin and EHDP. Eight patients suffered a recurrence after discontinuation of APD. In all cases scintigraphic deterioration also occurred, usually simultaneously or 6 months before the recurrence. In two patients with scintigraphic deterioration a recurrence could not be confirmed during this study. The scintigraphic deterioration presented as one of the three patterns seen after combination therapy.

Influence of pharmacological doses of calcitonin on serum beta 2 microglobulin concentration

The effect has been studied of continuous infusion of calcitonin in 14 hypercalcemic patients and 5 patients with Paget's disease of the bones. In all hypercalcemic patients but one, a good serum calcium lowering effect was obtained. In all subjects there was a significant decrease of serum beta 2 microglobulin concentration during calcitonin infusion (4.1 +/- 3.4 vs 2.9 +/- 2.5 mg . l-1; P less than 0.01). Especially in patients with an initial increased serum beta 2 microglobulin, a pronounced decrement of this serum beta 2 microglobulin was achieved. Moreover, a positive correlation was found between the drop in serum calcium concentration and the serum beta 2 microglobulin concentration before calcitonin infusion (r = 0.83; P less than or equal to 0.01). Urinary beta 2 microglobulin excretion did not change significantly during calcitonin infusion. These results led to the speculation that the serum calcium lowering effect of calcitonin is not only the result of the direct antiosteoclastic effect of this hormone but that some immunologic modulating effect of calcitonin on the monocyte macrophage system of the bones is contributory to this hypocalcemic effect of calcitonin.

Influence of treatment with APD-bisphosphonate on the bone lesions in the mouse 5T2 multiple myeloma

The effects of the treatment of multiple myeloma (MM) with APD-bisphosphonate on bone destruction, the dissemination pattern of the MM, and toxicity for normal and malignant cells were investigated in an animal model, the 5T2 MM. This mouse MM very closely resembles the human disease, including the typical bone lesions. It was demonstrated by radiography, microradiography, and histologic investigation that the treatment of the 5T2 MM with APD-bisphosphonate protected the mice against a loss of bone to a significant extent. It seemed that the treatment with APD not only diminished the bone destruction by the MM but also led to the formation of new bone in already-affected bone tissue. The growth pattern of the MM was not substantially influenced by the treatment, even though there was an indication that APD exerts some cytotoxic effect on the MM cells.

Efficacy of the bisphosphonate APD in the control of Paget's bone disease

Fifty-four patients with Paget's bone disease have been treated with the bisphosphonate APD. Twenty-six patients had not previously received treatment for Paget's disease; and 28 had been treated before with EHDP alone or in combination with calcitonin. APD was given orally in a mean dose of 500 mg daily (congruent to 6.8 mg/kg of body weight) for 4 to 12 months. Bone pain diminished or disappeared in 34 of 39 patients with symptoms. A very significant diminution of the biochemical indices of bone turnover was observed in all patients, but the responses were faster in patients who had not previously received treatment for Paget's disease. After 4 months of treatment the serum levels of alkaline phosphatase of previously untreated patients diminished from 58.8 +/- 8.0 to 20.0 +/- 3.9 KA units (P less than 0.001) and urinary excretion of hydroxyproline diminished from 108.6 +/- 16.9 to 42.4 +/- 8.3 mg/24 h (P less than 0.001). In 23 of 26 previously untreated patients the biochemical indices decreased to the normal range (complete response). A reduction of 50% or more without reaching the normal range was observed in the other 3 patients (partial response). Actuarial analysis of the duration of the effect 12 months after stopping APD disclosed that 63% of patients who had achieved a complete response but only 23% of those with a partial response were in biochemical remission. A second course of APD was administered to 11 patients. The results were as effective during the second as the first course in 9 patients, whereas 2 patients had no response to retreatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical experience with the use of two diphosphonates in the treatment of Paget's disease

The effects of EHDP (20 mg/kd/day) and APD (4.5 mg/kg/day) given for three months to patients with severe symptomatic Paget's disease have been compared in an open trial of 17 patients. Both drugs were equally effective in producing a prompt reduction in pair scores, urine hydroxyproline, and serum alkaline phosphatase levels. The remission was maintained for a variable period after stopping treatment. Both drugs were well tolerated, and a one-month course of either drug was not effective. Comparison with published responses from previous studies indicates that EHDP given at this dose as a relatively short course is more effective than a lower dose for a longer period of time; the present study does not suggest that APD has significant advantages.

The bisphosphonates HEBP and AHPrBP but not AHBP inhibit mineral mobilization and lysosomal enzyme release from mouse calvarial bones in tissue culture

The effect of 3 bisphosphonates, 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP), 3-amino-1-hydroxy-propylidene-1, 1-bisphosphonate (AHPrBP) and azacycloheptylidene-2, 2-bisphosphonate (AHBP), on the release of minerals (40Ca, 45Ca, Pi) and enzymes from cultured mouse calvaria was investigated in an organ culture system. HEBP and AHPrBP reduced PTH-stimulated mobilization of calcium and inorganic phosphate without affecting the release of lactate dehydrogenase. In contrast, no significant effect by AHBP on mineral mobilization and lysosomal enzyme release could be registered. In parallel with inhibited mineral mobilization, HEBP and AHPrBP inhibited the release of the lysosomal enzyme beta-glucuronidase. A possible cellular mechanism of action of bisphosphonates is discussed in the light of these data.

Apposition and resorption of bone during oral treatment with (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD)

The effects of 1.5-2 years oral administration of disodium (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) on bone metabolism were studied in male and female rats. APD was mixed in the food at levels of 500, 2,000 and 10,000 ppm. A dose-dependent increase in metaphyseal bone was found, indicative of continued inhibition of bone and cartilage resorption. APD did not affect mineralization of bone and cartilage, primary bone formation, or periosteal apposition. A short-term metabolic balance study was performed to compare the effects of oral with subcutaneous APD. Absorption of APD was in the order of 0.2%. Oral APD increased absorption of phosphate, probably by complexation of calcium with APD. The excess absorbed phosphate increased phosphaturia and decreased urinary calcium.

Effect of dichloromethylene diphosphonate (Cl2MDP) on immune function in breast cancer patients with bone metastases

Immune function was studied in normocalcemic breast cancer patients with bone metastases treated with either dichloromethylene diphosphonate (Cl2MDP) or placebo. The results showed no significant difference between the two patient groups. This suggests that Cl2MDP does not markedly impair the host's defense mechanisms, and in this respect can be safely used in the treatment of patients with resorptive bone disease.

Efficacy of amino-hydroxypropylidene bisphosphonate in hypercalcemia: observations on regulation of serum calcium

For 2 weeks 27 patients with hypercalcemia received a standard oral treatment with (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) as the sole agent. Results were grouped according to causes of hypercalcemia and compared with effects of APD in 13 normocalcemic patients with Paget's disease of bone and 7 with osteoporosis. In 12 hypercalcemic patients with osteolytic bone lesions and in the 20 normocalcemic patients, the mean serum calcium decreased to final levels that were subnormal and significantly lower than those obtained after treatment of 8 patients with primary hyperparathyroidism. In 3 patients with myeloma and in 4 tumor patients without bone lesions, serum calcium did not always decrease to the normal range. Implications of these observations for the mechanism of hypercalcemia are discussed.

The origin of osteoclasts

We are satisfied from studies with mi mi osteopetrotic mutant mice that osteoclasts arise from the myeloid tissue of bone marrow and not as formerly proposed from osteoprogenitor cells. Grafts of compatible normal myeloid cells cure the osteopetrosis by the substitution of the qualitatively defective osteoclasts with normal ones. Nevertheless it is still not fully clear through what cellular cascade this is effected. Current opinion would favour the pathway from pluripotent haematopoietic stem cells to circulating monocytes to tissue macrophages with ultimate fusion to form multinucleate osteoclasts. However, it is recorded that osteoclasts differ from macrophage polykaryons of inflammatory tissue not only in certain subcellular characteristics but in absence of Fc and C3 receptors. We can explain this as due to development through a specialised line of osteoclast precursors independent of conventional macrophages, if current unpublished experimental studies confirm the transfer to osteoclasts of the additional "beige" marker incorporated into grafted material.

Effects of disodium dichloromethylene diphosphonate on bone loss in paraplegic patients

21 paraplegic patients with recent traumatic spinal cord injury were orally administered 400 (n = 7) or 1,600 (n = 7) mg/d of disodium dichloromethylene diphosphonate (Cl2MDP) and compared with a placebo group (n = 7) to test the preventive effects of the drug on acute bone loss and osteoclastic resorption. Cl2MDP therapy was initiated at a mean of 17.6 d after the onset of paraplegia. The study lasted at least 6 mo, consisting of a 3.5-mo treatment period, and a variable follow-up period. The effects of Cl2MDP were assessed by blood and urine biochemistry, bone histomorphometry on transilial samples, photon absorptiometry of the tibia and fibula, and radiomorphometry of the femur. The elevation in serum and urinary calcium and in urine hydroxyproline observed in the placebo group did not appear under treatment. With both doses of Cl2MDP there was no further decrease in the bone mineral content. In the treated groups, a smaller percentage increase in osteoclastic population was also noted when compared with the placebo group, but this difference was not significant. There was no mineralization defect induced by Cl2MDP, as shown by tetracycline double labeling. It thus appears that at doses ranging between 400 and 1,600 mg, given as early as possible, Cl2MDP can prevent or reduce the development of the acute bone loss of paraplegic patients, without adverse side effects, though it does not prevent the development of heterotopic ossification.

Diphosphonates: history and mechanisms of action

The history of diphosphonates began with studies of inorganic pyrophosphate. This compound was found to occur in many biological fluids and inhibited the precipitation of calcium phosphates. It also slowed the transformation of amorphous calcium phosphate to its crystalline form, and inhibited crystal aggregation and dissolution. These observations suggested that it might be a compound of physiological or pathophysiological significance, perhaps in hypophosphatasia and in renal lithiasis. Diphosphonates are compounds where the P-O-P bond of pyrophosphate is replaced by a P-C-P bond. Many diphosphonates have been synthesized and tested and some relationship of their structure to the spectrum of biological effects has been observed. These analogues have similar properties to pyrophosphate, but unlike pyrophosphate they are resistant to enzymic degradation. Their experimental properties have led to their clinical development as bone scanning agents and in the treatment of disorders of ectopic mineralization and increased bone resorption.

Paget's disease of bone: diagnosis and management

The main features of Paget's disease are described, together with the indications for medical treatment. A brief summary is given of the drugs available for treatment of Paget's disease with particular emphasis on sodium etidronate (EHDP, ethylidene-1-hydroxy-1, 1-diphosphonate). Sodium etidronate, given at doses between 5 and 20 mg per kilogram per day for 3-6 months, causes a progressive reduction in the biochemical abnormalities (raised plasma alkaline phosphatase and urinary hydroxyproline) and in the histological abnormalities of bone. Clinical symptoms also improve. The usual dose is 5 mg per kilogram body weight per day to be given for not longer than 6 months. Higher doses (10 and 20 mg per kilogram per day) may cause impairment of normal bone mineralisation and should be given for short periods only (1-3 months). Sodium etidronate also has a limited place in the treatment of certain disorders of ectopic calcification, notably heterotopic ossification after spinal cord injury or hip surgery. At the present time there is insufficient evidence to justify its use in the treatment of renal stones or in osteoporosis other than that due to immobilisation after spinal cord injury.