Formulation of Aucklandiae Radix Extract-Loaded Nanoemulsions and Its Characterization and Evaluations In Vitro and In Vivo.

ABSTRACT

This study aimed to screen, design, and evaluate an optimal nanoemulsion formulation for Aucklandiae Radix extraction (ARE). A simple lattice design (SLD) method was used to determine the preparation process of Aucklandiae Radix extract-nanoemulsions (ARE-NEs). After optimization, the average particle size of ARE-NEs was 14.1 ± 1.1 nm, polydispersity index was 0.2376, and pH was 6.92. In vitro penetration tests verified that the permeability ratios of costunolide (CE), dehydrocostus lactone (DE), and ARE-NEs were approximately 6.33 times and 8.20 times higher, respectively, than those of the control group. The results of the pharmacokinetic study indicated that after topical administration, the content of the index components of ARE-NEs increased in vivo, with a longer release time and higher bioavailability in vivo than in vitro. The index components were CE and DE, respectively. In addition, a skin irritation test was conducted on normal and skin-damaged rabbits, aided by HE staining and scanning electron microscopy, to reveal the transdermal mechanism of ARE-NEs and proved that NEs are safe for topical application. ARE-NEs energetically developed the properties of skin and penetration through the transdermal route, which were secure when applied via the transdermal delivery system .