Nanovesicles of Sorbitan Isostearate: a Novel Sustained Release Non-Ionic Surfactant

Sorbitan isostearate (Span 120) is a novel non-ionic surfactant for development of vesicular systems. The present work aimed to develop, characterise and evaluate Span 120 based niosomes for enhanced drug delivery. Span 120 niosomes were prepared by using the thin-film hydration method and naproxen sodium was used as a model drug. Fourier transform infrared spectroscopy analysis was also done for preformulation studies. Niosomes prepared with Span 120 and cholesterol (2:1) were spherical, as shown by transmission electron microscopy, with a mean size of 173 +/- 2.96 nm, a polydispersity index of 0.28 +/- 0.02, a zeta potential of -50 +/- 1.2 mV and an entrapment efficiency of 91.92%. The in vitro release study showed a sustained release (21.9%) of naproxen sodium in 12 h. The release kinetics was uniform and followed the Korsmeyer-Peppas model, with n > 0.5. Accordingly, niosomes with a molar ratio of 2:1 was selected for in vivo anti-inflammatory activity. A carrageenan-induced paw oedema test was performed, which showed an enhanced inhibitory effect of loaded niosomes with Span 120 compared to the standard drug. In conclusion, the use of Span 120 is a promising approach to formulating niosomes with an improved and sustained effect.