Stability studies of silymarin nanoemulsion containing Tween 80 as a surfactant

Silymarin, a flavonolignan from "milk thistle" (Silybum marianum) plant is used almost exclusively for hepatoprotection. Because of its low bioavailability, it was incorporated into a nanoemulsion formulation. The aim of the present study was to check the stability of silymarin nanoemulsion at different temperatures for 3 months.

The oil-in-water based nanoemulsion formulation was prepared by titration method. Silymarin nanoemulsion was characterized by droplet size, viscosity, and refractive index. Droplet size, viscosity, and refractive index were determined every month. The shelf-life of silymarin nanoemulsion was determined by accelerated stability testing.

It was found that there was no significant change in the droplet size, viscosity, and refractive index at refrigerator and room temperature during the period of 3 months. The half-life of the optimized nanoemulsion formulation was found to be 4.74 years at room temperature.

These results indicated that stability of silymarin can be enhanced in nanoemulsion formulation using Tween 80 as a surfactant.