Topical delivery of pluronic F127/TPGS mixed micelles-based hydrogel loaded with glycyrrhizic acid for atopic dermatitis treatment

The purpose of this study was to develop pluronic F127/d-a-tocopheryl polyethylene glycol 1000 succinate mixed micelles-based hydrogel (MMs-gel) for topical delivery of glycyrrhizic acid (GL) to improve its skin permeability and atopic dermatitis (AD) treatment. GL loaded MMs-gel (GL-MMs-gel) could be potentially used as a promising nanocarrier for the treatment of AD. GL-MMs were prepared by thin film hydration method and then loaded into carbopol gel. The formulation of GL-MMs-gel was optimized by full factorial design and systematically characterized for drug content, pH, spreadability, in vitro drug release and percutaneous permeation, etc. The therapeutic effect of GL-MMs-gel was also investigated in AD-like skin lesion model in BALB/c mice and compared with GL solution-based gel (GL-sol-gel). Spherical GL-MMs with particle size of ∼30 nm were successfully incorporated into carbopol gel to form GL-MMs-gel with drug content of (98.80 ± 1.30) %, pH of 6.0 ± 0.08, and spreadability of (7.1 ± 0.2) cm. In vitro drug release profile of GL-MMs-gel exhibited a sustained-release behavior. The permeation flux for GL-MMs-gel (5.15 ± 0.33 µg/cm 2 /h) was significantly higher than that of GL-sol-gel (3.08 ± 0.34 µg/cm 2 /h) and GL-MMs-gel increased the accumulative amounts of GL in rats' skin 8.41 times than GL-sol-gel. The GL-MMs-gel was more effective than GL-sol-gel in suppressions of various AD symptoms including skin lesions, edema, high IgE levels, epidermal hyperplasia, and mast cell infiltration. All results revealed that MMs-gel could be a promising carrier for topical delivery of GL for the treatment of AD.