The aim of this paper is to propose equations for the diffusion of drugs for
investigated drug/hydrogel systems using the parameters affecting the
transport of drug through poly(2-hydroxyethyl methacrylate/itaconic acid)
(P(HEMA/IA)), poly(2-hydroxyethyl acrylate/itaconic acid) (P(HEA/IA)), and
poly(2-hydroxyethyl methacrylate/poly(alkylene glycol) (meth)acrylates)
(P(HEMA/BIS)) copolymeric hydrogels. Different monomer types, as well as the
variable content of some components in hydrogel composition (the amount of
ionizable comonomer (IA) and different type of nonionic poly(alkylene
glycol) (meth)acrylates), ultimately defined the pore size available for
drug diffusion. The hydrogels synthesized ranged from nonporous to
microporous, based on the classification in accordance to the pore size, and
could be classified as hydrogels that contain ionic groups and hydrogels
without ionic groups. The drugs selected for this study are
bronchodilators-theophylline (TPH), fenethylline hydrochloride (FE), and
antibiotic-cephalexin (CEX). Results of in vitro drug release tests defined
the release systems based on the drug type, as well as the type of hydrogel
used. The diffusion coefficient of drugs and the restriction coefficient, ,
defined as the ratio of solute to ?pore? radius (rs/r? ) that describes the
ease of drug release from the gels, were used as factors that govern the
release process.