Effect of Oil, Surfactant and Co-Surfactant Concentrations on the Phase Behavior, Physicochemical Properties and Drug Release from Self-Emulsifying Drug Delivery Systems

Microemulsions are isotropic, thermodynamically stable systems. The aim of this study was to evaluate the effect of oil, surfactant and co-surfactant concentrations on the phase behavior, physico-chemical properties and drug release of Self-Emulsifying Drug Delivery Systems (SEDDS). Solubility of artemether in Peceol® (oil), Labrasol® (surfactant), Transcutol® (co-surfactant) and their mixtures was studied while pseudoternary phase diagrams were constructed using water titration method as surfactant efficiency and water solubilization capacity were examined. Artemether SEDDS were prepared by dissolving artemether in the oil prior to further mixtures with surfactant, cosurfactants and characterized by evaluation of phase stability, self-emulsification, pH, viscosity, drug precipitation, refrigeration thaw cycle, centrifugation, drug release and dispersion. SEDDS prepared with surfactant-co-surfactant mixture (Smix) at 3:1 ratio had the largest zone of microemulsion in the pseudoternary phase diagrams and highest surfactant efficiency. Formulations with higher Labrasol® content showed faster self-emulsification, while artemether release and dispersion from capsule-filled SEDDS was optimum and fastest using Peceol®/ Smix ratio of 1:2 and a Labrasol®/Transcutol® ratio of 3:1. Combinations of oil, surfactant and co-surfactants at varied ratios produced self-emulsifying systems with different emulsification, drug release and dispersion qualities.