Spectroscopic analysis of triflusal impregnated into PMMA from supercritical CO2 solution

The applicability of supercritical carbon dioxide (scCO₂) as a solvent instead of organics has already been demonstrated for the impregnation of biopolymers with pharmaceuticals. This specific process enables the dispersion of a drug in a polymer and leads to further control of drug release. In this work, scCO₂ technology was employed to impregnate triflusal active agent and its hydrolysis metabolite 4-(trifluoromethyl) salicylic acid (HTB) into PMMA bars. Confocal Raman spectroscopy and high-pressure liquid chromatography were the main analysis techniques employed to characterize the degree of dispersion of the drug inside of the polymer. In the Raman analysis, obtained spectra were decomposed with several Gaussians functions. Hence, by using the decomposition of each spectrum it was possible to study the evolution of the concentration of the drug and its metabolite in hundreds of different positions along the radius of the polymer bar. Raman spectroscopy was also used to detect water in the PMMA matrix and to analyze its influence in the formation of the HTB. Finally, spectroscopic analysis showed that scCO₂ impregnation process resulted in triflusal and its metabolite being molecularly dispersed in the polymer matrix. Drug molecules interaction with PMMA chains was detected for the metabolite HTB, but not for triflusal.