ELUTION MECHANISM OF VANCOMYCIN AND GENTAMICIN FROM CALCIUM PHOSPHATE CEMENT

: We previously reported that the antibiotic elution profiles from calcium phosphate cement (CPC) vary depending on the type and number of impregnated antibiotics. Here, we attempted to determine the underlying factors affecting the elution of vancomycin (VCM) and gentamicin (GM) from CPC. Changes in pore size were investigated after the impregnation of CPC with various antibiotics in either the liquid or powdered state. Porosimetry analysis revealed that the pore sizes of CPC impregnated with powdered antibiotic were larger than those of CPC impregnated with liquid antibiotic. As powdered VCM had poor solubility in the CPC solvent, insoluble VCM particles would block the crystal growth. Scanning electron microscopy observation demonstrated that the solubility of VCM increased after the impregnation of CPC with GM. These findings suggest that the size of CPC pores, which act as passages for antibiotic elution, are affected by the size of undissolved antibiotic particles present within CPC.