G.O. Fulgêncio; B.M. Rezende; D.H. Lara; M.I. Yoshida; A.S. Cunha Junior; A.A.G. Faraco
Chitosan, a biodegradable and biocompatible polysaccharide, is a potentially useful material in various fields. We developed a simple chitosan films containing timolol maleate (TM) as a drug carrier for controlled release in ocular disease. The chitosan drug loaded films were produced by a casting/solvent evaporation technique. Chitosan solution (2 wt%) was prepared with 2 wt% acetic acid solution and distilled water. This solution was mixed with timolol maleate and was dried at room temperature for 24 h until film formation. The chitosan films were accurately observed and checked for possible imperfections by visual monitoring. This film was characterized by in vitro and in vivo release studies, swelling studies, DSC and ATR-FTIR. The total profile for water absorption was similar for the types of films developed. The analysis in ATR-FTIR showed that there were no new characteristics absorption bands on either drug loaded films leading to the conclusion that there was no obvious chemical reaction between the drug and the polymeric matrix. As an important result, timolol maleate probably did not lose its activity in the drug loaded films. No significant alteration was observed on the ATR-FTIR spectra. DSC curves of pristine TM, TM-loaded-film and placebo film showed a sharp endothermic peak at 212°C, which corresponds to the melting temperature of TM and peak endothermic at 100 and 273°C due to water loss and thermal decomposition, respectively. No peak was observed at 212°C in TM loaded-film indicating the amorphous dispersion of TM into film. In the drug release in vitro studies it was observed that 85% release from the film in two weeks. On the other side, the drug release in vivo studies showed that there was release from the film in three weeks. Therefore the more prolonged release from the film when compared to the conventional preparation (ophthalmic solution) was due to the properties of the film that acts as a reservoir of the drug, because of the polymeric matrix. These results suggested that the chitosan film prepared in this study might carrier of sustained-release drugs. Such a formulation offers the possibility of decreasing the number of applications, per day, of TM ophthalmic solution, and possibly a more intensive topical treatment in ocular diseases.