Targeted topical delivery of Ruxolitinib-Loaded nanoemulgel for potential management of Atopic Dermatitis: An integrated in silico, in vitro, and in vivo approach.

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disorder characterised by pruritus, epidermal barrier dysfunction, and immune dysregulation, significantly impacting quality of life. Conventional therapies, including corticosteroids, calcineurin inhibitors, and systemic immunosuppressants, provide mainly symptomatic relief with limited long-term efficacy and potential adverse effects. Additionally, Janus kinase (JAK) inhibitors such as Ruxolitinib (RUX) (Opzelura® 1.5 % w/w) have improved treatment outcomes, but their prolonged use causes folliculitis and increased risk of infections. To solve this existing problem, we developed a RUX-NEG to enhance the localised epidermal delivery, along with reducing systemic exposure by employing a low-dose NEG, which has a prolonged release profile and better therapeutic efficacy. Nanoemulsions containing 0.5, 0.75 and 1 % w/w RUX were optimised using a BOX-Behnken design, yielding nanosized droplets (∼16 nm) with a narrow size distribution. Incorporation of 1.5 % w/w high-molecular-weight hyaluronic acid provided suitable rheological characteristics, including pseudoplastic and thixotropic behaviour for improved topical application. The developed RUX-NEG exhibited notable antioxidant potential and significantly attenuated reactive oxygen species generation, mitochondrial membrane depolarisation, and cell death in LPS-stimulated HaCaT cells. Additionally, it suppressed pro-inflammatory mediators (TNF-α, IL-6, IL-8, IL-1β) and modulated NF- κB signalling pathways. Dermatokinetic evaluation demonstrated enhanced drug retention within AD lesions. Furthermore, in a 2,4-DNCB-induced AD mouse model, RUX-NEG effectively reduced inflammatory cytokines (TNF-α, IL-4, IL-6, IL-13) (ELISA), inhibited JAK1/JAK2 signalling (western blot) and improved histopathological alterations. Collectively, these findings highlight the potential of RUX-NEG as an effective topical delivery system for improving therapeutic outcomes and safety in the management of AD.