Formulation and evaluation of self-emulsifying orlistat tablet to enhance drug release and in vivo performance: factorial design approach.

The purpose of the present research work was to formulate, evaluate, and optimize self-emulsifying orlistat tablet to enhance drug release followed by in vivo antiobesity activity in Wistar rats. Initially, the solubility of orlistat was determined in different natural oils, surfactant, and co-surfactants. Self-emulsifying drug delivery system (SEDDS) was prepared by using castor oil, Tween 80, and Capryol PGMC as components. Liquid SEDDS evaluated for globule size and emulsification time. A 3(2) full factorial design was utilized for the optimization purpose. Formulation variables such as quantity of oil (X1) and ratio of surfactant to co-surfactant (X2) were investigated for their effect on globule size and emulsification time. Optimized formulation with minimum globule size was freeze-dried which further compressed into the tablet. Finally, optimized formulation evaluated for the in vitro drug release study followed by weight losing potential in Wistar rats. Globule size and emulsification time for the optimized formulation were found to be 96.4 ± 8.5 nm and 26 ± 4 s, respectively. Fourier transform infra red spectroscopy (FTIR) studies indicated that there was no interaction between drug and excipients. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) study revealed that there was the conversion of crystalline orlistat to the amorphous form. Orlistat release from the self-emulsifying tablet formulation was faster with higher weight reduction potential in Wistar rats than the marketed formulation. Increased in vitro drug release with considerable in vivo weight loss by self-emulsifying tablet suggests that the SEDDS could serve as potential formulation strategy for orlistat.