Topical film prepared with Rhus verniciflua extract-loaded pullulan hydrogel for atopic dermatitis treatment

Atopic dermatitis (AD) is characterized by relapsing pruritus and skin dryness. Due to the pathogenic multiplicity and the adverse effects associated with the current therapeutics, development of transdermal drug delivery system is becoming an area of interest. Here, a novel topical film prepared with Rhus verniciflua extract (RVE)-loaded pullulan hydrogel (RVE@PH) was synthesized and tested its therapeutic efficacy on the AD rats modeled by neonatal capsaicin injection method. The RVE@PH was characterized by a Fourier-transform infrared spectroscopy and an in vitro release assay. Rat pups were randomly divided into two groups: vehicle-treated (VEH; n = 5) and capsaicin-treated (n = 15). The latter were given capsaicin subcutaneously at 24 h after birth for AD induction and further divided into three groups (n = 5 per each): not treated (CAP), pullulan hydrogel-applied (PH), and RVE@PH-applied (RVE-PH). The pullulan hydrogel and RVE@PH were topically applied on shoulder lesions for 14 days (from 42 to 56 days after birth). Their phenotypes were compared based on the dermatitis score, epidermal thickness, mast cell infiltration, and serum myeloperoxidase (MPO) activities. The PH group showed significant attenuation in all the aforementioned values compared to the CAP group, suggesting that pullulan hydrogel itself has therapeutic activity against AD. Notably, the attenuations were more potent in the RVE-PH group than the PH group, indicating that the therapeutic efficacy against AD is augmented by the presence of RVE, a loaded pharmaceutic. Collectively, these results indicate that RVE@PH inhibits AD through exerting the dual roles, that is, the pullulan hydrogel-mediated physical and RVE-mediated pharmaceutical actions. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2325-2334, 2019.