Development and in vitro–in vivo evaluation of a water-in-oil microemulsion formulation for the oral delivery of troxerutin

Objective: The main objective of this study was to develop and evaluate a W/O microemulsion formulation of troxerutin to improve its oral bioavailability.Methods: The W/O microemulsion was optimized using a pseudo-ternary phase diagram and evaluated for physical properties. In vitro MDCK cell permeability studies were carried out to evaluate the permeability enhancement effect of microemulsion, and in vivo absorption of troxerutin microemulsion in the intestine was compared with that of solution after single-dose administration (56.7 mg/kg) in male Wistar rats.Results: The optimal formulation consisted of lecithin, ethanol, isopropyl myristate and water (23.30/11.67/52.45/12.59 w/w) was physicochemical stable and the mean droplet size was about 50.20 nm. In vitro study, the troxerutin-loaded microemulsion showed higher intestinal membrane permeability across MDCK monolayer when compared with the control solution. The W/O microemulsion can significantly promote the intestinal absorption of troxerutin in rats in vivo, and the relative bioavailability of the microemulsion was about 205.55% compared to control solution.Conclusion: These results suggest that novel W/O microemulsion could be used as an effective formulation for improving the oral bioavailability of troxerutin.