Characterization and In vitro Release Testing of Asiaticoside Dry Nanoemulsion prepared by Spray Drying

The pharmaceutical and nutraceutical fields are limited in their use of asiaticoside (AS) due to its poor solubility in water. The study used a spray drying technique to design an AS dry nanoemulsion with drug-releasing properties improvement. A combination of high-speed homogenization and ultrasonication methods prepared nanoemulsion. The nanoemulsion formulation containing virgin coconut oil or VCO (13.55%, w/w) as oil phase, sucrose ester (SE) with HLB 3 (2.5%, w/w) as surfactant, and sodium caseinate (SC) (2%, w/w) as co-surfactant. Nanoemulsion formulation followed by spray drying was carried out to improve the physical and chemical characteristics of the product. AS shows the highest solubility in methanol (> 30mg/mL), while the solubility of AS in water is 0.297mg/mL. The in vitro release test of pure AS and dry nanoemulsion in two different media shows significant differences. Compared to pure AS and its physical mixture, the cumulative dissolved AS percentage in dry nanoemulsion is greater, at 51.48% in 0.1 N HCl medium pH 1.2 and 48.72% in phosphate buffer saline (PBS) medium pH 6.8. The nanoparticle morphology of the dried nanoemulsion is spherical with a rough surface. The diffractogram of the dry nanoemulsion shows that AS changed from a crystalline state to an amorphous state. The thermogram of the dried nanoemulsion shows a loss of crystallinity of the AS. The dry nanoemulsion formulation demonstrates superior drug release characteristics compared to the physical mixture and pure form due to its smaller particle size. This enhanced dissolution leads to greater solute availability, potentially resulting in higher oral absorption and bioavailability of AS.