Papers by Keyword: Hydroxyfluorapatite

Abstract: Bisphosphonates (BP) are drugs currently administered orally to treat diseases characterised by an excessive bone resorption. Alternative and more efficient delivery routes and more potent compounds are being investigated. Three implantable delivery systems, which allow the controlled release of therapeutic agents from the device core, are examined in this paper. (4- (aminomethyl) benzene) bisphosphonic acid (ABBP) was incorporated on Ca8.8Na0.8(PO4)4.8(CO3)1.2(OH)0.4F1.6 particles by refluxing the powder in a 60 mmol suspension in acetone at 60°C for 5 hours. 4-aminophenyl acetic bisphosphonate monosodium salt (APBP) and 1- H-indole-3-acetic bisphosphonate monosodium (IBP) were loaded on Ca10(PO4)6(OH)1F1 ceramic bodies by stirring the ceramic bodies in 0.04M BP solutions. Injectable acrylic cements based on self-curing formulations of methyl methacrylate (MMA) and vitamin E were loaded with APBP and IBP. The incorporation of ABBP was confirmed by MAS-NMR spectroscopy. Modified powder shows two different phosphorous environments, the first one at 2.91 ppm can be assigned to the apatite base and the second one at 18.0 ppm has to be attributed to the phosphonic group of the ABBP. The IBP addition on ceramic surfaces did not decrease the number of osteoclast colonies and appeared to improve the performance of the HA as a surface for osteoblast culture. A therapeutic dosage of APBP and IBP can be achieved from acrylic cements that showed lack of toxicity and an increased cellular activity and proliferation.

Abstract: Bisphosphonates (BPs) may play an important role in minimizing osteolysis. In this work two new bisphosphonates pertaining to second and third generations respectively, have been synthesized and incorporated onto a chemically enriched hydroxyapatite. BP synthesis has been performed by adding H3PO3, PCl3 and methanesulfonic acid over 4-aminophenyl acetic acid (APBP) and 1-H-indole-3-acetic acid (IBP) respectively at 65°C in a N2 atmosphere. These compounds bear a primary amine group bonded to an aromatic ring, and a secondary amine group within a heterocyclic ring respectively. A chemically enriched hydroxyapatite with a chemical content corresponding to a 50% fluorided hydroxyapatite has been synthesized. Ceramic bodies manufactured by uniaxial pressure followed by cold isostatic press have a 97% density and submicron grain size. The BP was adsorbed onto the surface by immersion in a stirred solution at 37°C for 48 hours. A 10-fold decrease of the surface energy was observed for bodies modified with the APBP whereas only a 25 % decrease is obtained for bodies loaded with the bisphosphonate loaded with the IBP.