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In this study, interpenetrating polymer network (IPN) hydrogel based on polyvinyl alcohol (PVA) networking with polyacrylic acid (PAA) were prepared by a non-conventional emulsion method without any added crosslinker, using benzoyl peroxide as initiator and sodium chloride (NaCl) as additive. The IPN hydrogel was characterized by using Fourier transformed infrared (FTIR) spectrophotometry, Thermo gravimetric analysis (TGA), and Scanning electron microscopy (SEM). (PVA-co-PAA)/ NaCl normal IPN hydrogel (H) were fabricated into hydrogel microspheres (HM) by modified emulsion crosslinking method using glutaraldehyde-saturated toluene as crosslinker and were loaded with Diltiazem hydrochloride (DL). The IPN hydrogel showed more swelling in simulated intestinal fluid (SIF). (PVA-co-PAA)/NaCl HM for-mulation A1 showed comparatively higher DL entrapment (79%) and better control over DL release up to 24 h. By comparing antihypertensive activity of DL loaded two formulations in normotensive rats, HM formulation A1 found more effective in reducing blood pressure to 40.1%. The experimental results demonstrated that (PVA-co-PAA)/ NaCl HM had the greater potential than normal hydrogel to be used as a drug carrier. A single use of the prepared hydrogel microsphere system of DL can effectively control hypertension in rats. The system holds promise for clinical studies. V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 959-968, 2010

This work was intended to develop a new hydrogel of collagen-g-Poly (acrylamide-co-itaconic acid) through chemical cross-linking by graft copolymerization of acrylamide (AM) and itaconic acid (IA) on to collagen (CGN) via redox initiator system of ammonium persulfate (APS) and N, N, N', N'-tetramethylethylenediamine (TMED), in presence of N, N'-methylene bis acrylamide (MBA) as crosslinking agent. Characterization of the hydrogel was done by FT-IR, TGA, SEM, LCMS/MS and HPLC. Valsartan (VAL) was successfully loaded into the prepared hydrogel. CGN-g-P(AM-co-IA) (H 10 ) formulation showed highest swelling capacity as well as VAL release in the biological media and release was controlled up to 24h. The release data of various formulations were fitted to Zero order, First order and Higuchi's kinetic models. It was observed that the release of drug from all the formulations followed Higuchi's kinetic model as its value of coefficient of determination is greater than that of others.

In order to modify the xanthan gum (XG) polysaccharide and to develop the hydrogels meant for the drug delivery, we have prepared XG-g-poly [HEMA-co-AA] superporous hydrogel (SPH) through chemical cross-linking by graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) on to XG via redox initiator system of ammonium persulfate (APS) and N, N, N', N'-tetramethylethylenediamine (TMED), in the presence of N, N'-methylenebisacrylamide (MBA) crosslinking agent, sodium bicarbonate foaming agent, a triblock copolymer of polyoxyethylene/ polyoxypropylene/ polyoxyethylene as a foam stabilizer. Characterization of SPH was done by FT-IR, TGA, SEM, HPLC and GCMS. The prepared SPH were successfully loaded with Doxofylline (DF) drug and formulation H 10 showed higher % drug content (98±2.3) and % drug entrapment efficiency (83±2.0). From the in Vitro drug release study in pH progressive media, formulation H 10 showed comparatively higher release extending upto 24h.The mechanism of DF release from the SPH matrix was found to be of diffusion type.