Polyvinyl alcohol--gelatin patches of salicylic acid: preparation, characterization and drug release studies.

Polyvinyl alcohol-gelatin patches were developed and salicylic acid was incorporated at different stages of preparation of the patches. The patches were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry, tensile strength test, and scanning electron microscopy. The release patterns of the drug from the patches were also studied. The FTIR spectra of the blank patch indicated complete esterification of the free carboxylic groups of gelatin. The XRD studies indicated a crystalline form of the drug entrapped in the patches. Release of the drug from the patches followed Higuchian/Fickian kinetics indicating a diffusion-controlled release process.