Effects of the preparation methods of hydroxypropyl methylcellulose/polyacrylic acid blended films on drug release.

Hydroxypropyl methylcellulose (HPMC)/polyacrylic acid (PAA) blended films were prepared under different conditions (i.e. temperature, solvent, and cross-linking agent). The effects of hydrogen-bonding interactions or a chemical reaction between the two-component polymers in the blended films on drug release were studied. Two model drugs were used for comparison: a water-soluble drug, dl-propranolol hydrochloride, and a lipophilic drug, ketoprofen. The H-bonding interaction of HPMC/PAA was found to be stronger in the blended films prepared from H2O than that from H2O/EtOH. However, the H-bonding effect between HPMC and PAA on drug release is indistinct. Chemical esterification of the carboxylic acid groups of PAA with the hydroxyl groups of HPMC was proposed from the solid-state NMR, ESCA, and FTIR studies when the blended films were dried at 110 degrees C. This chemical reaction also resulted in insolubilization of the blended films.