AN INVESTIGATION OF FB INTERACTIONS WITH POLY(ETHYLENE GLYCOL)-6000, POLY(ETHYLENE GLYCOL)-4000, AND POLY-EPSILON-CAPROLACTONE BY THERMOANALYTICAL AND SPECTROSCOPIC METHODS AND MODELING

The interactions between flurbiprofen (FB) and different polymers are studied in order to improve the bioavailability of FB. FB-polymer phas e diagrams [poly(ethylene glycol) (PEG) 4000, PEG 6000, and poly-epsil on-caprolactone] were constructed and compared with the modeling diagr ams: Thermoanalytical methods (differential scanning calorimetry, ther momicroscopy) were used to construct the phase diagrams. Thermodynamic data were used to model the FB-polymer systems. The construction of t he FB-polymer phase diagrams showed the existence of a stable invarian t called ''eutectic'' characterized by (X-E)(exp), (T-fE)(exp), and (D elta H-fE)(exp), the experimental eutectic composition, the experiment al temperature, and the enthalpy of eutectic melting, respectively, Mo deling confirmed the values for these parameters and was used to evalu ate the different Flory-Huggins parameters X for each FB-polymer mixtu re. X values and the infrared spectra confirm that the interactions du e to hydrogen bonds between FB and PEG 4000 are more numerous than bet ween FB and PEG 6000 and also more numerous than between FB and poly-e psilon-caprolactone.