The Thai Journal of Pharmaceutical Sciences


A self-microemulsifying delivery system (SMEDS) containing astaxanthin (AST) was developed and optimized using a mixture design and its desirability function. Independent factors studied in the experimental design were the amounts of castor oil, Cremophor® RH 40, and Tween® 80 in a formula. The measured response variables included droplet size, polydispersity index (PDI), zeta potential, active ingredient content, and transmittance of microemulsions obtained from the AST SMEDS formulations. The desirability function was then adjusted to optimize the formulation. The optimized AST SMEDS was composted of 19.59% castor oil, 62.34% Cremophor® RH 40, and 18.03% Tween® 80, and the resulting self microemulsions had an average droplet size of 22.55 nm with PDI of 0.27, zeta potential of –9.35 mV, 96.49% of AST content, and 98.80% of transmittance. Our results also showed the optimized formula could rapidly formed (self-emulsification time ~44 s) AST microemulsions with good physicochemical properties and stability conducted by the freeze-thaw study. Moreover, the in vitro release profiles of AST from the optimized SMEDS formulation were significantly improved compared to a marketed preparation and raw AST powder. The design of experiments and optimization of these novel AST SMEDS formulations were a promising approach to enhance dissolution of poorly water-soluble AST.



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