Formulation and characterization of W/O/W crystallizable double emulsions stabilized by OSA starch/xanthan gum mixture as drug delivery systems

Abstract

Water-in-oil-in-water (W/O/W) crystallizable double emulsions stabilized with a mixture of octenyl succinic anhydride starch (OSA starch) and xanthan gum (XG) were formulated. These systems were proposed as modules for the release of chlortetracycline (CTC). The characterization results indicated that the stability, the average diameter of the globules, and the apparent viscosity of the double emulsions formulated depend on OSA starch and XG concentrations, and on their ratio in the outer water phase. In addition, emulsions exhibited good creaming stability during 40 days of rest at 25 °C and 40 °C. However, samples prepared with 0.25%/0.5% and 0.5%/0.5% of OSA starch/XG mixture were found more stable. Also, it was noticed that the encapsulation efficiency (EE) and the release rate of CTC incorporated in the inner water phase strongly depend on the polymer concentrations in the outer water phase. Furthermore, the increase in the concentration of biopolymer results in a slowing down of the drug encapsulation and an improvement in the EE. Moreover, the Korsmeyer-Peppas model was tested to represent the kinetics of CTC release; the release mechanism was found as a simple diffusion type.