Diffusion of drugs in hydrogels based on (meth)acrylates, poly(alkylene glycol) (meth)acrylates and itaconic acid

Abstract

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.