Development, optimization and evaluation of emodin loaded nanoemulsion prepared by ultrasonic emulsification

Emodin loaded nanoemulsion (EMO-NE) was optimized by using response surface methodology (RSM) based on central composite design to investigate the influence of main formulation variables as well as ultrasonic operating parameters on the properties of nanoemulsion. Furthermore, in order to find the best compromise between several responses, the desirability function was optimized the responses successfully. RSM analysis demonstrated that the experimental data can be fitted into a second-order polynomial model and actual values of the formulated nanoemulsion were in a good agreement with predicted values. The optimal formulation was mainly constituted with 11.84% (w/w) capryol 90 containing emodin, 20.16% (w/w) cremophor RH 40/transcutol HP. Ultrasonic operating time was set as 23.42 min and the operating power was set at 156 w. The introducing of oleic acid and pH adjustment can easily improve the zeta potential of EMO-NE. The mean zeta potential of the optimized EMO-NE was -25.2 +/- 0.5 mV and the diameter was in the range of 10-30 nm. About 80.79 +/- 1.11% of emodin was found to be released from EMO-NE in vitro after 120 h, and it was assumed that drug releasing mechanism is following a Fickian diffusion mechanism. (C) 2015 Elsevier B.V. All rights reserved.