ABSTRACT
Synthetic polymer hydrogels are gaining interest for the control release of the drugs because of their good biocompatibility and water permeation properties. Interpenetrating polymer network (IPN) type hydrogel has proved to be more promising nowadays on account of its interlocked morphology along with hydrophilicity to hold as well as release the drug in required rate. The IPN is defined as a special class of polymer alloys, in which the possibility of phase separation has been arrested to a great extent by suitably engineering the morphologies of the participating components. In IPNs, one polymer is synthesized or cross-linked in the immediate presence of the other and they are at least partially interlaced on a molecular scale but not covalently bonded to each other and cannot be separated unless chemical bonds are broken. Also an IPN can be made suitable as carrier of drug delivery system, for periodic administration as required in chronic infection via oral or systemic routes when it is made biocompatible. Various studies have established that the local application of antibiotics provides high concentration of drug at the site of infection with a low systemic toxicity (Kaul et al., 2005; Nelson, 1987). Different local drug delivery systems with antibiotics have been attempted; however the most widely studied material has been an antibiotic-acrylic composite. Hydrophilic acrylics, for example poly acrylic acid, polyacrylamide, poly(2-hydroxyethyl acrylate), poly(hydroxylethyl methacrylate) and so on, are used for biocompatibility and/or biodegradability (Frutos et al., 2002; Majid et al., 1985; Nelson et al., 1993). The weight ratio of hydrophilic and hydrophobic components taken in the polymer blend, controls a range of properties for example, porosity, biocompatibility, toughness, % drug loading and release, swelling characteristics and cross-linking density etc. These are by far the leading factors governing the diffusional transport properties of the drugs into the matrix. Ferrer et al. showed formation of nanodomains (30-100 nm) in hydrophilic-hydrophobic IPN based on poly(2-hydroxyethyl acrylate) and poly(ethyl acrylate) and suggested their suitability for cell adhesion on that basis (Ferrer et al., 2007).
