Fluid properties of various Eudragit® solutions in different solvent systems for periodontal pocket injection

Abstract

Eudragit® are polymethacrylate-based polymers used for pharmaceutical dosage form development especially for sustained drug release devices. Their fluid properties have not been investigated when using organic solvents used in an in situ forming gel (ISG) for periodontal drug delivery via injection. This research attempted to prepare ISG solutions by dissolving Eudragit® E, Eudragit® L, Eudragit® S, Eudragit® RL and Eudragit® RS in different solvents such as dimethyl sulfoxide (DMSO), N-methyl pyrrolidone (NMP), 2-pyrroridone (PYR), eutectic mixture (1:1 menthol:camphor) and clove oil. Type of these solvents influenced on Eudragit® solubility, density, viscosity, rheology and injectability. NMP could dissolve all types of Eudragit®. Whereas, eutectic solvent could dissolve only the Eudragit® E. The other solvent could dissolve only some specific types of Eudragit®. The completely dissolved solutions were selected for investigation. Density of all Eudragit®-loaded solutions appeared higher significantly than that of the solvent. Moreover, Eudragit® L in NMP showed the highest density. The obtained solutions mostly exhibited Newtonian flow. By comparison, the viscosity of Eudragit® RS in NMP was less than Eudragit® RL ≪ Eudragit® S < Eudragit® L, respectively. All of them needed the force of injection <50 N indicating acceptable injectability. Therefore, Eudragit®-loaded solution using NMP as the solvent was chosen for drug loading in future research for periodontitis treatment. Because Eudragit® type and solvent markedly influenced their fluid properties, the application for using Eudragit® solution in pharmaceutical dosage forms should be considered.