S.H. Scharla

Methylpentylaminopropylidenebisphosphonate (BM 21.0955): a new potent and safe bisphosphonate for the treatment of cancer-associated hypercalcemia

Bisphosphonates have been shown to be effective in lowering serum calcium levels in patients with cancer-associated hypercalcemia. 1-Hydroxy-3-(methylpentylamino)propylidenebisphosphonate (BM 21.0955) was developed as a third generation bisphosphonate and has been recently proven effective in animals and in patients with Pagets disease or tumor osteolysis. Thirty-six patients with cancer-associated hypercalcemia were treated with increasing doses (0.2-2.0 mg) of BM 21.0955 by single i.v. infusion over 4 h in a phase I trial. Six patients were rejected from analysis due to concomitant treatment with other bisphosphonates or chemotherapy. After rehydration and infusion of BM 21.0955 the mean serum calcium levels fell significantly (P < 0.001), from 3.29 +/- 0.49 mmol/l to 3.04 +/- 0.44 mmol/l until day 2 and normalized on day 6 (2.66 +/- 0.33 mmol/l). Serum calcium was reduced in all patients and normalized in 16. No symptomatic hypocalcemia occurred. Mean serum creatinine decreased significantly (P < 0.01), from 1.25 +/- 0.58 mg/dl (day 0) to 1.05 +/- 0.37 mg/dl (day 6). The mean urinary calcium/creatinine concentration fell significantly (P < 0.001), from 1.90 +/- 1.16 mM/mM (day 0) to 0.37 +/- 0.34 mM/mM/l (day 6). There were no subjective drug-related side effects during or after the infusion. Thirteen patients had elevations of morning body temperature above 38 degrees C. This was due to confirmed infections in five patients and possibly drug- or tumor-related in the other eight. We conclude from these preliminary results that a single infusion of BM 21.0955 is an effective and safe way to treat cancer-associated hypercalcemia.

1,25-dihydroxyvitamin D3 prevents the decrease of bone mineral appositional rate in rats with inflammation-mediated osteopenia (IMO)

We have studied the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on bone mass and bone mineral appositional rate in intact rats and rats with inflammation-mediated osteopenia (IMO), where osteoblast number and mineral appositional rate are decreased. 1,25(OH)2D3 prevents IMO-specific bone loss when given in a daily dose of 25 ng per rat, but does not when given in higher doses. The hormone was effective, when given over the complete duration of the experiment (21 days), but not when given over shorter time periods (7 and 14 days, respectively). 1,25(OH)2D3 prevents IMO-dependent reduction in mineral appositional rate and leads to an only moderate increase in intact rats. We conclude, that 1,25(OH)2D3 is more effective in stimulating mineral appositional rate in rats with IMO where mineral apposition is impaired.

Superior local tolerability of human versus salmon calcitonin preparations in young healthy volunteers

SummaryPossible local and systemic adverse effects following administration of salmon (sCT) and human (hCT) calcitonin (CT) have been evaluated in a double-blind, within-subject, comparative trial in 30 young, healthy volunteers. Each subject received 0.25 and 0.5 mg hCT and 100 IU sCT s.c.. Adverse effects and hypocalcaemia were recorded 1, 3 and 6 h after each injection.Significantly fewer local adverse reactions were observed after hCT (20 or 33%) than after sCT (80%), possibly due to the different vehicles employed (mannitol solution and acetic acid).The most frequent systemic adverse effects were gastrointestinal (nausea, vomiting), which occurred in 80% after 1 h, independently of the CT — preparation used. Hypocalcaemic changes were generally small and lasted longer after sCT.It is concluded that the hCT preparations were better tolerated locally than sCT in young, healthy volunteers, and that there were no differences in the systemic side effects or hypocalcaemic activity.

Inflammation-mediated osteopenia (IMO): No change in bone resorption during its development

Bone loss in rats with In f lammat ion-Media ted Osteopenia (IMO) (I, 21 was first attributed to increased bone resorption (21. Later, morphological studies showed, however, that bone resorption was not increased but formation was inhibited and attributed to osteoblast reduction in number and activity (3). Nevertheless, we observed, that the bisphosphonate APD was found to inhibit the development of IMO (4), although the drug is thought not to influence osteoblast function but only to inhibit osteoclast activity (5). Thus we hypothesized, that IMO might possibly be also dependent on activation of osteoclasts. It has been shown, that 3Htetracycline released from bone of prelabelled animals is poorly incorporated into newly formed bone, thus representing a better tool to study bone resorption than 6SCa, which is strongly reincorporated (6). 3H-tetracycline-release from bone of prelabeled rats can also be detected in urine and has been used as a method for continual monitoring of bone resorption in the mouse (71 and the rat (8). Therefore, we studied in this paper osteoclast activity in rats with IMO applying the technique of urinary 3H-excretion in 3H-tetracycline prelabelled rats (8).

The hypercalcemic Walker carcinosarcoma 256 of the rat causes an increase in serum 1,25-dihydroxyvitamin D3

We have studied vitamin D metabolism in rats with the transplantable hypercalcemic Walker carcinosarcoma 256, which is a well characterized animal model for humoral hypercalcemia of malignancy. 25-Hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) concentrations were determined in blood samples obtained from parathyroidectomized (PTX) female rats at different time intervals after intramuscular tumor cell inoculation. We observed a dramatic increase in serum 1,25(OH)2D3 (280 +/- 184 vs. 98 +/- 31 pmol/l) 6 days after tumor cell injection and 4 days after the initial rise of serum calcium, whereas 25(OH)D3 tended to decrease. In a separate control experiment we compared this to the effect of exogenous parathyroid hormone in PTX rats and found similar results. In contrast, rats exhibited no change in vitamin D metabolite blood concentration after inoculation of the normocalcemic Yoshida sarcoma, which obviously does not interfere with vitamin D metabolism. We conclude that the humoral bone-resorbing agent produced by the Walker tumor cells causes elevation of serum 1,25(OH)2D3 concentration by this fulfilling an additional criterion of PTH-like activity.

Therapie des Morbus Paget mit dem Bisphosphonat Pamidronat (AHPrBP, früher APD)

SummaryWe studied the effect of the intravenous administration of the bisphosphonate pamidronate (AHPrBP) in 7 patients with Pagets bone disease. The medication was given in a daily dose of 20 mg for 9 days in 0.9% saline infusion over 4 hours (total dose 180 mg). Thereafter the patients received no therapy. At the end of treatment a slight but significant fall of plasma calcium (p≤0.01) was observed, but no patient displayed hypocalcemia. The urinary excretion of hydroxyproline fell below 45% of initial within 6 days of treatment. Only 3 out of 7 patients showed a decline in alkaline phosphatase activity (AP) already at the end of treatment, but after 3 to 6 months AP was below 30% of the initial value in all observed patients. After 9 months no relapse of AP was observed. Roentgenograms demonstrated dramatic improvement of bone lesions in one case. Hyperthermia occurred in 2 patients as side effect; one patient developed headache. However, treatment could be continued in all cases.The short-term intravenous administration of pamidronate is a useful means to suppress the activity of Pagets disease and no further treatment is necessary at least for several months.

Influence of parathyroidectomy, 1,25-dihydroxyvitamin D3 and high dietary calcium intake on demineralized bone matrix powder-induced bone formation in the rat

Demineralized bone matrix induces ectopic endochondral bone formation. We used this model to study the effect of parathyroidectomy (PTX), 1,25-dihydroxyvitamin D3 treatment, and calcium enriched diet on bone formation in the rat. Hypocalcemia and hyperphosphatemia in PTX rats were corrected by 1,25-dihydroxyvitamin D3 treatment (2 x 12.5 ng/day) or by calcium enriched diet (3% calcium). Serum 1,25-dihydroxyvitamin D3 concentration was decreased in PTX rats and in intact rats with high dietary calcium intake. Calcium content of ectopic new bones (42 days after bone matrix implantation) was reduced in PTX rats compared with intact control rats. This could be prevented by 1,25-dihydroxyvitamin D3 treatment. In contrast, calcium enriched diet led to diminished mineralization of ectopic bones both in intact and PTX rats. We conclude that the effect of parathyroidectomy on bone formation may be mediated by 1,25-dihydroxyvitamin D3. 1,25-Dihydroxyvitamin D3 directly stimulates bone formation in this model and this effect is not simply the result of increasing serum calcium concentration.

Evaluation of an Automated Competitive Protein-Binding Assay for 25-Hydroxyvitamin D

BACKGROUND The measurement of 25-hydroxyvitamin D is of increasing importance in the management of patients with mineral disorders. However, there are a great variety of test results for 25-hyroxyvitamin D depending on the method used. In this report a new automated method provided by Roche diagnostics (Elecsys Vitamin D Total assay) and the previously marketed method are compared to a reference method (Immundiagnostik ELISA). Further, we tested the new Roche method for its ability to monitor vitamin D supplementation. METHODS Serum aliquots of 80 consecutive patients were prepared and 25-hydroxyvitamin D was measured by two automated methods provided by Roche diagnostics and by ELISA (Immundiagnostik, Bensheim, Germany). Further, we collected samples from 80 osteoporosis patients on vitamin D supplementation (1000 IU daily) and measured serum 25-hydroxyvitamin D using the Roche Elecsys Vitamin D Total assay. RESULTS The new Roche Vitamin D Total assay showed better correlation with the ELISA (r = 0.73) than the old automated method (r = 0.41). The 25-hydroxyvitamin D values obtained with the old automated Roche method were much lower compared to the new method or the ELISA, resulting in overestimation of vitamin D deficiency. In this respect, the new Roche Vitamin D Total assay was in rather good agreement with the ELISA. Moreover, the application of the new Roche Vitamin D Total assay in the monitoring of vitamin D supplementation gave clinically useful results: 90% of the patients receiving 1000 IU of vitamin D3 daily had a 25-hydroxyvitamin D serum concentration of > 50 nmol/L, which is in the expected range. Moreover, the 25-hydroxyvitamin D concentrations were negatively correlated to PTH proving the plausibility of the results. CONCLUSIONS 25-hydroxyvitamin D measurements show a large variability. Results from previous studies obtained with the old Roche automated method should be used with caution. The new automated Roche Vitamin D Total assay exhibits a reasonable concordance with the ELISA and can be used for monitoring patients in clinical practice. However, because of the variability, the results for individual patients are of limited use and general population based screening for vitamin D deficiency cannot be advocated.