pH dependent hydrogel formulations of venlafexine HCl were prepared by free radical
polymerization method using polyethylene glycol as polymer. Various samples were prepared
with varying concentration of polymer, monomer and cross-linker to study their effect
on gel swelling, diffusion characteristics and drug release. Swelling was found to
be increased with increase in pH. Increase in acrylic acid concentration increases
swelling while increase in cross-linker concentration has an opposite effect on swelling.
Drug release study was performed in pH 1.2, 5.5 and 7.5for 12 hours at 37 oC and drug
release was found to increase in higher pH. Prepared hydrogel preparations were also
characterized by PXRD, TGA, SEM and FTIR.