Modulation of cytosolic calcium levels in osteoblast-like osteosarcoma cells by olpadronate and its amino-derivative IG-9402.

The molecular mechanisms as well as the structure/activity relationships involved in the antiresorptive actions of bisphosphonates on bone cells are still not clear. Replacement of the R1-hydroxyl by an NH2 group in olpadronate (OPD) abolishes its antiresorptive activity. We show here that in the rat osteosarcoma-derived osteoblast-like ROS 17/2.8 cell line, OPD and IG-9402 (NH2-OPD; [3-(N,N-dimethylamine)-1-aminopropylidene bisphosphonate]), similar to 1,25(OH)2-vitamin D3, rapidly modulate cytosolic calcium levels ([Ca2+]i). As for the steroid hormone, the osteosarcoma cell Ca2+i response to OPD was rapid (30 sec) and sustained (>5 min), exhibiting a biphasic profile. The response to IG-9402 was also fast but smaller than that of OPD and 1,25(OH)2D3, and rapidly declined to levels near basal. The effect of these bisphosphonates on [Ca2+]i was dose-dependent, being maximal at 10(-8) M and was not observed in non-bone cellular systems, e.g., skeletal muscle and breast cells. Pretreatment of the ROS 17/2.8 cells with the Ca2+ channel blockers nifedipine and verapamil markedly reduced (>70%) the influx phase of the response to OPD and almost completely inhibited that of IG-9402, indicating the participation of voltage-dependent Ca2+ channels in the action of both compounds. Moreover, preincubation with the phospholipase C inhibitors U73122 and neomycin or depletion of inner stores with thapsigargin completely blocked the response to either olpadronate or its amino-derivative. Both OPD and IG-9402 significantly increased osteocalcin release into the culture medium of osteosarcoma cells. The results support the involvement of the Ca2+ signaling pathway as part of the mechanism by which bisphosphonates induce bone cellular responses.

Serum kinetics, bioavailability and bone scanning of 99mTc-labelled sodium olpadronate in patients with different rates of bone turnover.

The activity of olpadronate labelled with technetium-99m(99mTc) was monitored in plasma and urine samples after single oral (925 MBq 99mTc/10 mg, coadministered with 50 mg cold drug) and intravenous (925 MBq 99mTc/5 mg) administrations to two groups of patients with different rates of bone turnover. The first group comprised high bone turnover (HBTO) patients suffering from Paget's bone disease; the second group comprised patients with normal to low bone turnover (NBTO) having the diagnosis of rheumatoid arthritis and secondary osteoporosis. Kinetic variables were correlated with anthropomorphometric variables, biological markers of bone metabolism and plasma proteins. Data were also obtained after repeatedly dosing the HBTO patients. Additionally, Paget's bone and healthy bone (PB/HB) uptake before and after low-dose oral treatment were assessed by means of scintigraphy. Results showed that most of the kinetic variables did not differ between the two groups of patients, except for a greater Vss and smaller blood area under the curve AUC in the patients with HBTO. After a repeated-dose administration period, the blood AUC activity and Whole Body Retention (WBR) of the HBTO patients tended to be similar to those of the NBTO patients. In both groups, after oral dosing, the Cmax was 20 times lower than the C0.5 after i.v. injection, and the oral bioavailability ranged from 3% to 4%. Finally, the plasma t1/2 beta ranged from 9 to 14 h. Correlation coefficients were obtained from multiple regression analysis; kinetic variables showed very low correlations with anthropomorphometric measurements. In contrast the Vss and WBR were significantly correlated with serum alkaline phosphatase levels and the Vss also with urine hydroxyproline levels. Plasma protein concentration was also correlated with excretion parameters such as CLP and plasma t1/2 beta after an oral dose. Scintigraphic studies in the HBTO group allowed bone selectivity to be seen through skeletal drug uptake. The 15 Pagetic lesions analysed in the HBTO group showed a decrease in PB/HB ratio from 3.8 in the basal study to 2.7 after olpadronate administration for 30 days at the rate of 50 mg/day. In conclusion, the kinetic profile of 99mTc-labelled olpadronate, mainly AUC and WBR, showed a dependence upon bone metabolism and seemed unrelated to body size variables. HBTO patients showed a lower blood AUC but a higher Vss. Both variables may have been reflecting the fact that the drug binds selectively with calcified tissues and, in turn, with the target compartment. Scintigraphy confirmed the labelled-compound bone selectivity as a desirable feature for a bone-scanning agent.

Preliminary study of multiple increasing oral doses of dimethyl-APD on bone metabolism dynamics and safety profile.

A random block study, with 50, 100, 200 and 400 mg of 3-dimethylamino-1-hydroxypropylidene-1, 1-bisphosphonate or dimethyl APD and 300, 600 and 900 mg of 3-amino-1-hydroxypropylidene-1, 1-bisphosphonate or pamidronate (APD), in daily oral doses, showed that all doses were active when assessed in patients with Paget's bone disease. Dimethyl APD administration was followed by an increase in 1.25 (HO)2D levels, an effect that must be confirmed. Neither severe side effects nor significant laboratory abnormalities were detected despite some decrease in white blood cell count seen with the higher dose of APD. Gastrointestinal tolerance of dimethyl APD was acceptable but further investigation is required.

Double blind radiological assessment of continuous oral pamidronic acid in patients with rheumatoid arthritis.

Continuous oral pamidronate (APD), 1000 mg/day, was administered to 14 patients with rheumatoid arthritis. A control group of 13 patients with similar conditions received placebo under a double blind randomized study design. Periarticular erosion scores were significantly higher in the control group after 12 months treatment. This was attributed to a deterioration in this group rather than to an improvement in the APD treated one. By contrast, intraarticular narrowing score was not influenced by APD. Tolerance to oral APD was acceptable in all patients.

Protective effects of disodium etidronate and pamidronate against the biomechanical repercussion of betamethasone-induced osteopenia in growing rat femurs.

To assess the protective effect of bisphosphonates on the biomechanical repercussion of glucocorticoid-induced osteopenia, intraperitoneal doses of 1 or 10 mg/kg/d of disodium etidronate or 1 or 50 mg/kg/day of pamidronate were given to groups of 6 growing rats simultaneously receiving subcutaneous doses of 4.8 mg/kg/day of betamethasone for 20 days. Betamethasone impaired strength and stiffness of femur diaphyses through a reduction of geometric properties, abnormally enhancing bone ability to absorb energy. Both bisphosphonates partially prevented betamethasone effects on diaphyseal stiffness (but not strength) through positive, dose-related effects on material modulus of elasticity and slighter improvements in diaphyseal geometry, avoiding the enhancement of energy-absorbing ability and the subsequent tendency to production of comminute fractures. These results and others obtained treating normal rats with (pamidronate) APD suggest that the sign of bisphosphonate effects on bone biomechanics may depend not only on the type of compound but also on eventual interactions with concomitant treatments.

Osteoporosis: detección, prevención, tratamiento / Osteoporosis: detection, prevention and treatment

El síndrome osteoporótico se caracteriza por una merma en la cantidad (osteopenia) y deterioro de la calidad (microarquitectura) de la mineralización ósea. Se trata de trastornos heterogénos originados por múltiples causas metabólicas, poco conocidas. Se diagnostica por la presencia de deformaciones óseas o fracturas de origen no traumático. La detección precoz de la osteopenia es importante y se considera que los individuos cuya densidad mineral ósea (BMD) es inferior al 80// del normal están más expuestos a fracturas. La fosfatasa alcalina sérica, la hidroxiprolina y las piridinolinas urinarias son marcadores bioquimicos. Se insiste en los aspectos nutricionales y de movimientos físicos, para obtener una mayor masa ósea, especialmente durante el período de crecimiento. Es fundamental ingerir suficiente cantidad de calcio, y en las zonas más australes del país debe aumentarse el consumo de vitamina D. Los recursos terapéuticos tienden a prevenir la osteopenia de un modo más activo. Los estrógenos son muy utilizados en las mujeres postmenopáusicas. Son eficaces pero no para tratar la osteoporosis establecida y persisten todavía algunas dudas sobre su inocuidad a largo plazo. Las calcitoninas aumentan transitoriamente la mineralización vertebral y pueden ser utilizadas como alternativas de las terapias hormonales de reemplaxo. Los bifosfonatos presentan diferentes mecanismos de acción, p.ej., el pamidronato no es citotóxico por lo que no interfiere en el proceso de remodelación fundamental para mantener o mejorar la calidad arquitectónica del hueso. El efecto de los bisfosfonatos sobre la mineralización es duradero. Por ser drogas nuevas aún no han sido aprobadas en todos los países. Las sales de flúor han producido siempre resultados desconcertantes; algunos efectos benéficos iniciales no previenen las consecuencias adversas del uso prolongado. Las vitaminas D, el nitrato de galio y la ipriflavona producen resultados discretos que aún deben compararse con el de los agentes más activos. El empleo de otras drogas (tamoxifeno, los derivados de la parthormona, los factores de crecimiento, las tiazidas y los inhibidores de la bomba de protones) aún está en desarrollo. Se concluye que la osteoporisis es un proceso patológico que acompaña al envejecimiento y para el cual ya existen fármacos disponibles, en especial para prevenir la osteopenia y el deterioro de la calidad del hueso

Osteoporosis: detección, prevención, tratamiento / Osteoporosis: detection, prevention and treatment

El síndrome osteoporótico se caracteriza por una merma en la cantidad (osteopenia) y deterioro de la calidad (microarquitectura) de la mineralización ósea. Se trata de trastornos heterogénos originados por múltiples causas metabólicas, poco conocidas. Se diagnostica por la presencia de deformaciones óseas o fracturas de origen no traumático. La detección precoz de la osteopenia es importante y se considera que los individuos cuya densidad mineral ósea (BMD) es inferior al 80// del normal están más expuestos a fracturas. La fosfatasa alcalina sérica, la hidroxiprolina y las piridinolinas urinarias son marcadores bioquimicos. Se insiste en los aspectos nutricionales y de movimientos físicos, para obtener una mayor masa ósea, especialmente durante el período de crecimiento. Es fundamental ingerir suficiente cantidad de calcio, y en las zonas más australes del país debe aumentarse el consumo de vitamina D. Los recursos terapéuticos tienden a prevenir la osteopenia de un modo más activo. Los estrógenos son muy utilizados en las mujeres postmenopáusicas. Son eficaces pero no para tratar la osteoporosis establecida y persisten todavía algunas dudas sobre su inocuidad a largo plazo. Las calcitoninas aumentan transitoriamente la mineralización vertebral y pueden ser utilizadas como alternativas de las terapias hormonales de reemplaxo. Los bifosfonatos presentan diferentes mecanismos de acción, p.ej., el pamidronato no es citotóxico por lo que no interfiere en el proceso de remodelación fundamental para mantener o mejorar la calidad arquitectónica del hueso. El efecto de los bisfosfonatos sobre la mineralización es duradero. Por ser drogas nuevas aún no han sido aprobadas en todos los países. Las sales de flúor han producido siempre resultados desconcertantes; algunos efectos benéficos iniciales no previenen las consecuencias adversas del uso prolongado. Las vitaminas D, el nitrato de galio y la ipriflavona producen resultados discretos que aún deben compararse con el de los agentes más activos. El empleo de otras drogas (tamoxifeno, los derivados de la parthormona, los factores de crecimiento, las tiazidas y los inhibidores de la bomba de protones) aún está en desarrollo. Se concluye que la osteoporisis es un proceso patológico que acompaña al envejecimiento y para el cual ya existen fármacos disponibles, en especial para prevenir la osteopenia y el deterioro de la calidad del hueso (AU)

[Osteoporosis. Detection, prevention, and treatment]. / Osteoporosis. Detección, prevención, tratamiento.

The osteoporotic syndrome is characterized by a reduction in quantity (osteopenia) and damage of the quality (microarchitecture) of bone mineralization. These are heterogeneous disturbances caused by multiple not well known metabolic causes. It is diagnosed by the presence of bone deformations or non-traumatic fractures. The early detection of osteopenia is important and it is considered that individuals whose bone mineral density (BMD) is lower than 80% of the normal value, are more exposed to fractures. Serum alkaline phosphatase, hydroxyproline and urinary pyridolines are biochemical markers. Nutritional aspects and physical movements are emphasized to obtain a larger bone mass, specially during the growing period. It is absolutely necessary to ingest enough quantity of calcium and in the southern regions of the country consumption of Vitamin D must be increased. Therapeutical resources tend to prevent osteopenia more effectively. Estrogens are greatly used in postmenopausic women for the prevention but not for the treatment of osteoporosis once established. They are effective but there still exist some doubts about the innocuousness of long term treatments. Calcitonines increase vertebral mineralization temporarily and may be used as alternatives of replacement hormonal therapies. Bisphosponates present different mechanisms, for example, pamidronate is not cytotoxic and for this reason does not interfere in the remodelling process, which is absolutely necessary to maintain or improve the architectural quality of the bone. The effect of bisphosphonates on mineralization is lasting. As they are new drugs, they have not yet been definitely approved in every country. Fluorine salts have always produced controversial results, some favourable initial effects do not prevent adverse consequences in a long treatment. Vitamin D, gallium nitrate and ipriflavone produce fairly good results, which must still be compared with those of the more active agents. The use of other drugs (tamoxifeno, parathormone, growth factors, thiazide and inhibitors of the proton pump) is still under development. It is concluded that osteoporosis is a pathologic process of ageing, for which there are pharmaceutical products available, specially to prevent osteopenia and bone damage.

Osteoporosis. Detección, prevención, tratamiento. / [Osteoporosis. Detection, prevention, and treatment]

The osteoporotic syndrome is characterized by a reduction in quantity (osteopenia) and damage of the quality (microarchitecture) of bone mineralization. These are heterogeneous disturbances caused by multiple not well known metabolic causes. It is diagnosed by the presence of bone deformations or non-traumatic fractures. The early detection of osteopenia is important and it is considered that individuals whose bone mineral density (BMD) is lower than 80

of the normal value, are more exposed to fractures. Serum alkaline phosphatase, hydroxyproline and urinary pyridolines are biochemical markers. Nutritional aspects and physical movements are emphasized to obtain a larger bone mass, specially during the growing period. It is absolutely necessary to ingest enough quantity of calcium and in the southern regions of the country consumption of Vitamin D must be increased. Therapeutical resources tend to prevent osteopenia more effectively. Estrogens are greatly used in postmenopausic women for the prevention but not for the treatment of osteoporosis once established. They are effective but there still exist some doubts about the innocuousness of long term treatments. Calcitonines increase vertebral mineralization temporarily and may be used as alternatives of replacement hormonal therapies. Bisphosponates present different mechanisms, for example, pamidronate is not cytotoxic and for this reason does not interfere in the remodelling process, which is absolutely necessary to maintain or improve the architectural quality of the bone. The effect of bisphosphonates on mineralization is lasting. As they are new drugs, they have not yet been definitely approved in every country. Fluorine salts have always produced controversial results, some favourable initial effects do not prevent adverse consequences in a long treatment. Vitamin D, gallium nitrate and ipriflavone produce fairly good results, which must still be compared with those of the more active agents. The use of other drugs (tamoxifeno, parathormone, growth factors, thiazide and inhibitors of the proton pump) is still under development. It is concluded that osteoporosis is a pathologic process of ageing, for which there are pharmaceutical products available, specially to prevent osteopenia and bone damage.

Biomechanical effects of the full range of useful doses of (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) on femur diaphyses and cortical bone tissue in rats.

The effects of i.p. doses of 0.016, 0.16, 1.6, 5, 16, 50 and 160 microM/kg/day of APD, over a period of 23 days, on geometric and biomechanical properties of femoral diaphyses in bending were determined in groups of seven growing rats. Both elastic and ultimate strength increased with low doses and decreased with high doses. Geometric (mass) variables (diaphyseal volume, wall/lumen ratio) correlated positively, and material properties (limit elastic stress, modulus of elasticity) negatively, with log dose. Normal mass and improved quality at low doses, and improved mass and impaired quality data at high doses were obtained. No changes in sectional moment of inertia (Ix, an expression of bone architecture) were observed. Biphasic changes in diaphyseal strength expressed the effects of APD on material quality in spite of mass variation. The contrasting lack of changes in Ix may have reflected the blocking effect of APD on osteoclast-osteoblast communication, essential for directional modulation of remodelling.