Spectroscopic and chromatographic characterization of triflusal delivery systems prepared by using supercritical impregnation technologies

This study describes the development and evaluation of an analytical method for the characterization of triflusal (2-acetoxy-4-(trifluoromethyl) benzoic acid) dispersed in sustained delivery systems prepared using supercritical fluid impregnation technology. Characterization assays comprised the determination of the percentage of triflusal and its degradation product impregnated in polymeric supports and further monitoring of the releases of the two drug components over time in physiological conditions. Preliminary delivery profiles were monitored spectrophotometrically using a continuous-flow system. In this case, no selective wavelength for discriminating between triflusal and metabolite was found so that measurements at 225 nm provided overall profiles corresponding to the two compounds. For a more accurate study, a chromatographic method was developed for monitoring the evolution of the concentration of the two components independently. Triflusal and metabolite were separated in a C18 column and 25 mM acetic acid/acetate (pH 5.0) + methanol (40/60 v/v) mobile phase. Several triflusal-polymer samples were prepared under different experimental conditions and release features were evaluated. Excellent delivery systems were obtained with poly(methyl)methacrylate beads treated at 40°C and 190 bar for 48 h using supercritical carbon dioxide as a solvent. These samples showed a constant sustained release of drug for several weeks.