Abstract
Incorporation of drugs into non-ionic surfactant vesicles (niosomes) during their manufacture affords a possible method of achieving controlled release. The aim of this study is to formulate niosomes as carriers for delivery of diclofenac sodium (DCS). Niosomes are prepared with a series of sorbitan monoesters (Span 20, 40, 60, and 80) and sorbitan tri-oleate (Span 85) and co-surfactants of polyoxyethelene fatty acid esters (Tween 20, 40, 60, and 80), with or without cholesterol and charged lipids like stearylamine or dicetylphosphate. The prepared niosomes were evaluated for the entrapment efficiency (EE %) and in-vitro release rate of DCS. Niosomes formed of Span 60 gave the highest EE %, followed by Span 40, 20, 80 and 85. It was also found that increasing the total lipid concentration resulted in an increase in the EE %. However, the amount of encapsulated DCS (mg) per mmole lipid decreased. Increasing the concentration of DCS was accompanied by a slight increase in the EE % and a great increase in the entrapment efficiency expressed as mg/mmole lipid. Niosomes prepared by ether-injection method and reverse-phase evaporation method resulted in a marked increase in the EE % compared to those prepared by hand-shaking method. It was demonstrated that the uses of co-surfactants like different types of Tween with Chol in a molar ratio of 25:25:50 caused an increase in the EE %. Niosomes prepared from Span 40 and 60 showed the slowest release rate than those prepared from Span 20, 80 and 85. However, the incorporation of co-surfactants into niosomes resulted in a greater decrease in the release rate of DCS from niosomal vesicles.