N-Isopropylacrylamide (NIPA) has been copolymerized with itaconic acid (IA) in the presence of N,N-methylenebisacrylamide (BIS) as crosslinker. The swelling capacity and the release rate of aminophylline at 37 °C are reported. Maximum equilibrium swelling increases as the itaconic acid content in the hydrogel increases. The experimental data suggest clearly that the swelling process obeys second-order kinetics. According to this, the kinetic constant, k, and the maximum equilibrium swelling, W∞, have been calculated. Drug release from fully swollen hydrogels follows Fick's law closely, but deviates from it for xerogels.
© 2001 Society of Chemical Industry