N,N-Dimethylacrylamide Hydrogels for Controlled Drug Delivery. Influence of Network Structure and Drug Solubility on the Load and Release Mechanisms

Abstract

The aim of the present work was to synthesize sustained-release hydrogels based on N,N-dimethylacrylamide (DMA) to study the effect of the polymer matrix structure and the solubility of drugs on the load and release mechanisms. A series of cross-linked DMA hydrogels were synthesized with different monomer concentration and crosslinker to monomer ratio by free radical aqueous solution polymerization at 37ºC using N,N-methylen-bis-acrylamide as crosslinking agent. The effect of total monomer concentration and degree of crosslinking on the water absorption, glass transition temperature values, mechanical properties, and load/release of different drugs was studied. Main results showed that: a) the structure of the network, obtained by varying the monomer and crosslinking agent concentration, is a factor that governs the chemical and physical properties of the hydrogel (water absorption, glass transition temperature, storage and loss moduli, network parameters), b) the rate and amount of drug released from swellable hydrogels depend on both the degree of hydrogel crosslinking and the water solubility of the drug. In all cases, as the concentration of the crosslinker agent increased, the swelling capacity of the hydrogels was reduced and drugs with high solubility in water were more easily released, probably due to their greater affinity for the medium.