Methylmethacrylate sulfopropylmethacrylate copolymer nanoparticles for drug delivery - Part II: arecaidine propargyl ester and pilocarpine loading and in vitro release

Methylmethacrylate (MMA) sulfopropylmethacrylate (SPM) copolymer nanoparticles were prepared by free radical polymerization and the loading characteristics of the muscarinic agonists arecaidine propargyl ester (APE) and pilocarpine were investigated. The loading efficiency was mainly influenced by the concentration of the copolymer carrier system and followed Langmuir's adsorption equation. The in vitro drug release was mainly influenced by the composition of the acceptor phase used and the nanoparticle content of the donor phase. The bound drug was released from the carrier by competitive replacement by other ions from the binding sites of the particles. By this mechanism the nanoparticle system achieved a prolonged drug release, which was not the result of the increased viscosity at higher nanoparticle concentrations. (C) 1997 Elsevier Science B.V.