Controlled release of tinidazole and theophylline from chitosan based composite hydrogels

• Composite hydrogels were synthesized from acrylic acid and chitosan.
• Hydrogels were characterized by FTIR, NMR, DTA–TGA and XRD.
• Swelling, diffusion, network parameters of the hydrogels were evaluated.
• Release of theophyllene and tinidazole drugs from the hydrogels were studied.

Several composite hydrogels were synthesized by free radical crosslink copolymerization of acrylic acid (AA) and N′ methylene bis-acrylamide (MBA) in the presence of chitosan (CS). During polymerization CS was incorporated in situ in the crosslinked polyacrylic acid gel to produce composite hydrogels. The structure and properties of the hydrogels were characterized by FTIR, 13C NMR, DTA–TGA, XRD, swelling and diffusion characteristic and also network parameters. The loading and the in vitro release behaviours of theophylline and tinidazole model drugs were studied with these hydrogels. The wt% of CS and MBA and pH of the medium was found to strongly influence the drug release behaviour of the gels. Accordingly, the release rate of these two drugs was much faster at pH of 7.6 than at pH 1.5.