Preparation and in vitro evaluation of chitosan matrices cross-linked by formaldehyde vapors

Rifampicin-chitosan matrices were prepared by a chemical cross-linking meth od to develop a sustained-release form. The effects of cross-linking agent (formaldehyde) on the drug release rate and release kinetics were investiga ted in this study. Moreover, the kinetics of rifampicin released from chito san matrices exposed to formaldehyde vapors for predetermined time interval s were analyzed using Ritger and Peppas exponential equation. The in vitro release kinetics exhibited a non-Fickian transport model. Increasing the ex posure time to formaldehyde vapors decreased the release rate of rifampicin from chitosan matrices as a result of formation of greater structural stre ngth and tighter texture.