Eudragit Polymer Encapsulated Hydroxyapatite Microspheres As A Carrier For The Sustained Release Of Small Molecular Drugs

The adsorption/desorption of oleanolic acid hemiphthalate disodium (OPS) with hydroxyapatite microspheres (HAPm) was investigated. XPRD and FT-IR analysis indicated a highly dispersing state of UPS on HAPm, and weak physical interaction between OPS and HAPm. OPS loaded HAPm (OPS-HAPm) was encapsulated with Eudragit RS using the S/O/W emulsion-solvent evaporation method. Both the desorption of OPS from HAPm and the release of OPS from the Eudragit encapsulated HAPm were greatly affected by factors including the volume, pH, types, and ionic strength of the release medium. The polymer encapsulated OPS-HAPm showed sustained drug release profiles with no obvious initial burst release in various release medium, the drug release rate can also be tailored by utilizing various polymer/HAPm ratios in the encapsulation of OPS-HAPm. These results indicate great potential of polymer encapsulated HAPm as the carrier for the modified release of small, molecular, water soluble drugs.