In-vitro and in-vivo antibacterial activity evaluation of a polyurethane matrix

Various in-vitro and in-vivo methods for evaluation of the duration of antibacterial activity were compared using a controlled-release polyurethane matrix developed for the prevention of surface bacterial adhesion and growth. Cefadroxil was incorporated into this polyurethane matrix by a solvent casting method before the matrix was coated with polyurethane in tetrahydrofuran solution. The release of cefadroxil from the matrix into distilled water at 37 degrees C was measured by HPLC. The morphological change of matrices before and after release studies was investigated by scanning electron microscopy (SEM). The duration of antimicrobial activity of the matrix against Escherichia coli and Staphylococcus aureus was evaluated by measuring the diameters of the inhibition zone and the optical density of the broth. The matrices were also implanted subcutaneously in rats and the duration of the antibacterial activity was determined by measuring the inhibition zone. The results showed that duration of antibacterial activity of the polyurethane matrix was successfully determined in-vitro by these methods, and the results differed from the conventional in-vitro release study. It was also possible to determine the duration of action of the matrix in-vivo by implanting the matrix in rats, and then measuring the antibacterial activity of the matrix at predetermined time intervals. While a good correlation was observed between the in-vitro and in-vivo methods used in this study to evaluate the duration of the antibacterial activity of the polymeric matrix, the conventional in-vitro release study did not coincide with these results.