Theophylline release from poly(acrylic acid-co-acrylamide) hydrogels

Hydrogels are hydrophilic polymers that swell to an equilibrium volume in the presence of water but preserve their shape. The dynamic swelling behavior of poly(acrylic acid-co-acrylamide) copolymers, at 37 °C, was investigated. It was observed that the liberation mechanism was non-Fickian. Diffusion coefficients according to Ficks law as a function of concentration of N,N′-methylenebisacrylamide and results on the effects of crosslink density on the release of theophylline are reported.