Nicotine-selective poly(acrylamide/maleic acid) (AAm/MA) hydrogels prepared by gamma -irradiation were used in experiments on swelling, diffusion, and interactions of the pharmaceuticals nicotine, nicotinic acid, nicotinamide. and nikethamide. For AAm/MA hydrogel containing 60 mg maleic acid and irradiated at 5.2 kGy, the studies indicated that swelling increased in the following order; nicotine > nicotinamide > nikethamide > nicotinic acid > water. Diffusions of water and the pharmaceuticals within the hydrogels were found to be non-Fickian in character. AAm/MA hydrogel sorbed only nicotine and did not sorb nicotinamide, nikethamide and nicotinic acid in the binding experiments. S-type adsorption in Giles's classification system was observed. Some binding and thermodynamic parameters for AAm/MA hydrogel-nicotine system were calculated using the Scatchard method. The values of adsorption heat and free energy of this system were found to be negative whereas adsorption entropy was found to be positive. (C) 2001 Elsevier Science.