Detection, by X Ray Diffraction, of new bisphosphonate polymorphs of alendronate and risedronate treated hydroxyapatite

FERNÁNDEZ DE RAPP M.E.; FABREGAS ISMAEL OSCAR

Madrid

Congreso; XXII congress and general assembly IUCR; 2011

Introduction: We studied the physicochemical characteristics of the processes taking place on the     surface of the bone of osteoporotic people treated with bisphosphonates. In vitro essays  were performed in osteoporetic human bones and in synthetic hydroxyapatite (Ha). Alendronate  and risedronate were used to treat bone samples and synthetic Ha. Both drugs are used almost  exclusively in anti-resorptives therapies for bone diseases, and in post-operative treatments for cancer  ablation (breast, prostate, etc.) Methods: The nano hydroxyapatite was synthesized by the  sol/gel method. The material obtained was analyzed by x-ray diffraction and Scherrer equation to determine its crystallinity. The X-ray diffraction (diffractometer and radiation synchrotron) pattern  of synthetic hydroxyapatite was compared with healthy human bone obtaining an excellent   correspondence. The lattice parameters were determined by the Rietveld method. Scanning   Electron Microscopy was used to obtain the Ca/P ratio and transmission electron microscopy to  study the microstructure. In Vitro treatment simulating the natural conditions in which the drugs interact with the patient bones and synthetic hydroxyapatite (temperature and medium) was   performed using alendronate and alendronate/risedronate respectively. Results: None of the  analysis methods used was able to match a known polymorph to that found on the surface of the bone. They were able to ascertain that its composition was the same, in all cases, to thatof the known polymorph.