A three-component mixture system was optimized using D-optimal mixture design. The explored mixture systems include oil (OFI), surfactant (Tween 20), and cosurfactant (PEG 200). The components’ percentages in each mixture were summed up to 100%. The used percentages, selected on the basis of preliminary study results (data not shown), were as follows: oil; OFI (X1, 10–40%), surfactant; Tween 20 (X2, 30–50%), and cosurfactant; PEG 200 (X3, 20–40%). Average globule size of the prepared system (Y) was studied as response. The experimental runs were generated by Design-Expert® Software Version 11 (Stat-Ease Inc, Minneapolis, Minnesota, USA). The design points set by the software included combinations at vertices, edge centers, and edge thirds, and reinforced by check blends and an overall centroid. Accordingly, the proposed design consisted of 20 runs that included 5 replicate points and 4 center points (Table 1). The measured size was fitted to various sequential models. Fit statistics criteria were calculated to pick up the best fitting polynomial model. The effect of the components’ percentages on the globule size was evaluated by analysis of variance (ANOVA) at P < 0.05. The composition of the optimal formulation was predicted by numerical optimization, and desirability function was computed. The goal of the optimization process was to minimize the globule size of the formulated system.

The Composition of OFI-SNEDDSs Prepared Based on D-Optimal Mixture Design and Their Measured Globule Size

Note: *The percentages of each run are summed up to 100.