Strontium ranelate--a promising therapeutic principle in osteoporosis.
ABSTRACT Strontium ranelate (2g/day) appears to be a safe and efficient treatment of osteoporosis (OP), reducing the risks of both vertebral and non-vertebral fractures (including hip) in a wide variety of patients. Thus, the agent can now be considered as a first-line option to treat women at risk of OP fractures, whatever their age and the severity of the disease. A long-term treatment with strontium ranelate in OP women leads to a continued increase in bone mineral density at spine and hip levels, and a sustained antifracture efficacy. The mode of action of strontium ranelate involves a dissociation between bone resorption and formation, as the bone formation rate is increased and not influenced by the antiresorptive action of the agent. Strontium is heterogeneously distributed in bone tissue: it is absent from old bone tissue and is exclusively present in bone formed during the treatment. Total area containing strontium in bone tissue increases during treatment, although the focal bone strontium content is constant. Whatever the duration of treatment and the content of strontium in bone, the degree of mineralization is maintained in a normal range. Furthermore, no change at crystal level is detected up to 3 years of treatment.
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ABSTRACT: Strontium ranelate has been used to prevent bone loss and stimulate bone regeneration. Although strontium may integrate into the bone crystal lattice, the chemical and structural modifications of the bone when strontium interacts with the mineral phase are not completely understood. The objective of this study was to evaluate apatite from the mandibles of rats treated with strontium ranelate in the drinking water and compare its characteristics with those from untreated rats and synthetic apatites with and without strontium. Electron energy loss near edge structures from phosphorus, carbon, calcium and strontium were obtained by electron energy loss spectroscopy in a transmission electron microscope. The strontium signal was detected in the biological and synthetic samples containing strontium. The relative quantification of carbon by analyzing the CK edge at an energy loss of ΔE=284eV showed an increase in the number of carbonate groups in the bone mineral of treated rats. A synthetic strontium-containing sample used as control did not exhibit a carbon signal. This study showed physicochemical modifications in the bone mineral at the nanoscale caused by the systemic administration of strontium ranelate.Micron 10/2013; · 1.88 Impact Factor
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ABSTRACT: The classical simulated body fluids method cannot be employed to prepare biomimetic apatites encompassing metallic ions that lead to very stable phosphates. This is the case for heavy metals such as uranium, whose presence in bone mineral after contamination deserves toxicological study. We have demonstrated that existing methods, based on alternate dipping into calcium and phosphate ions solutions, can be adapted to achieve this aim. We have also especially studied the impact of the presence of carbonate ions in the medium as these are necessary to avoid hydrolysis of the contaminating metallic cations. Both the apatite-collagen complex method and a standard chemical (STD) method employing only mineral solutions lead to biomimetic apatites when calcium and carbonate ions are introduced simultaneously. The obtained materials were fully characterized and we established that the STD method tolerates the presence of carbonate ions much better, and this leads to homogeneous samples. Emphasis was set on the repeatability of the method to ensure the relevancy of further work performed on series of samples. Finally, osteoblasts cultured on these samples also proved a similar yield and standard-deviation in their adenosine triphosphate content when compared to commercially available substrates designed to study of such cell cultures.Biomedical Materials 12/2013; 9(1):015003. · 2.17 Impact Factor
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ABSTRACT: The present work investigates the preparation of biomimetic nanocrystalline apatites co-substituted with Mg, CO3 and Sr to be used as starting materials for the development of nanostructured bio-devices for regeneration of osteoporotic bone. Biological-like amounts of Mg and CO3 ions were inserted in the apatite structure to mimic the composition of bone apatite, whereas the addition of increasing quantities of Sr ions, from 0 up to 12 wt.%, as anti-osteoporotic agent, was evaluated. The chemical–physical features, the morphology, the degradation rates, the ion release kinetics as well as the in vitro bioactivity of the as-prepared apatites were fully evaluated. The results indicated that the incorporation of 12 wt.% of Sr can be viewed as a threshold for the structural stability of Mg–CO3-apatite. Indeed, incorporation of lower quantity of Sr did not induce considerable variations in the chemical structure of Mg–CO3-apatite, while when the Sr doping extent reached 12 wt.%, a dramatically destabilizing effect was detected on the crystal structure thus yielding alteration of the symmetry and distortion of the PO4. As a consequence, this apatite exhibited the fastest degradation kinetic and the highest amount of Sr ions released when tested in physiological conditions. In this respect, the surface crystallization of new calcium phosphate phase when immersed in physiological-like solution occurred by different mechanisms and extents due to the different structural chemistry of the variously doped apatites. Nevertheless, all the apatites synthesized in this work exhibited in vitro bioactivity demonstrating their potential use to develop biomedical devices with anti-osteoporotic functionality.Materials Science and Engineering C 01/2014; 35:212–219. · 2.40 Impact Factor