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

Hydrogels are hydrophilic polymers that swell to an equilibrium volume in t he presence of water but preserve their shape. The dynamic swelling behavio r of poly(acrylic acid-co-acrylamide) copolymers, at 37 degrees C, was inve stigated. It was observed that the liberation mechanism was non-Fickian, Di ffusion coefficients according to Ficks law as a function of concentration of N,N'-methylenebisacrylamide and results on the effects of crosslink dens ity on the release of theophylline are reported. (C) 1999 Elsevier Science Ltd. All rights reserved.