Naproxen niosomes prepared with various nonionic surfactants mixed with cholesterol

Abstract

Nonionic surfactant based vesicles are drug delivery systems formed from the self-assembly of nonionic amphiphiles in aqueous media. The objective of this study was to design, formulate, evaluate, and optimize the Naproxen niosomes using different sorbitan monoesters. The effects of two independent variables, Hydrophilic lipophilic balance (HLB) of nonionic surfactants and cholesterol content, on the characteristics of Naproxen niosomes were evaluated and optimized using factorial design and response surface methodology. Nine batches were prepared by the modified ethanol injection method and their individual and cumulative effects on vesicle size, and encapsulation efficiency (EE) as well as in vitro drug release over 24 h (D24h) were investigated. Graphical plot construction and optimization processes were performed using Minitab software. Naproxen could successfully be entrapped into all of the formulations with encapsulation efficiency percentage ranging between 51.1 and 63.5 % and could be released in the range of 39.6-71.1 % during 24 h. Niosomes were prepared in the size range of 221.3 and 431.3 nm. Loading efficiency and drug release were markedly dependent on the cholesterol content and HLB values of nonionic surfactants. The highest loading efficiency was observed in niosomes prepared from Span 60 (HLB 4.7) and cholesterol content of 50 %. The optimization process indicated that the optimum HLB value and cholesterol content were 7.5 and 40 % respectively which led to high EE% (56 %) and D24h (62 %) as well as appropriate particle size (300 nm). Ethanol injection method is a simple and rapid technique for preparation of niosomes, and statistical design is a beneficial approach to achieve the optimized formulations. © ECV