Novel chitosan-based pH-sensitive interpenetrating network microgels for the controlled release of cefadroxil

This paper addresses development of novel pH-sensitive interpenetrating polymeric network (IPN) microgels (MGs) based on chitosan, acrylamide- grafted-poly(vinyl alcohol) and hydrolyzed acrylamide- grafted-poly(vinyl alcohol) that are crosslinked with glutaraldehyde and used in the controlled release (CR) of cefadroxil, an antibiotic drug. The MGs formed were characterized by Fourier transform infrared spectroscopy to confirm the grafting and crosslinking reaction, scanning electron microscopy to understand the surface morphology and differential scanning calorimetry to conform a uniform distribution of the drug in the polymer matrix. Swelling experiments on hydrogels provided important information on drug diffusion properties. In vitro release results performed in acidic and basic media affected the drug release characteristics. Release data have been analyzed using an empirical equation to understand about the transport of drug containing solution through the polymeric matrices. Extent of crosslinking was studied in terms of size of MGs as well as their release characteristics. Effect of drug loading on encapsulation efficiency was investigated to find a linear manner. IPN matrices of this study were able to extend the release rates from conventional dosage release times to more than 10 h.