Formulation and Evaluation of a Nanoemulsion Gel for the Improved Topical Delivery of Dithranol in Psoriasis

Introduction: Psoriasis is a chronic, immune-mediated, inflammatory skin condition characterized by the hyperproliferation of keratinocytes. Dithranol is an established antipsoriatic agent with limitations in topical delivery due to poor skin permeation and irritation. Nanoemulsion gels offer an advanced approach to enhancing drug delivery and reducing adverse effects. Method: A dithranol nanoemulsion gel was prepared using high-speed homogenization followed by ultrasonication, employing linseed oil, Tween 80, PEG 400, Carbopol 940, and badam gum. Characterization included FTIR, DSC, particle size, PDI, zeta potential, viscosity, spreadability, drug content, in vitro drug release, and accelerated stability studies. An in vivo anti-psoriatic evaluation was conducted using an imiquimod-induced psoriasis model. Results: The optimized nanoemulsion gel had a particle size of 176.7 nm, a PDI of 0.189, and a zeta potential of -41.7 mV. DSC and FTIR confirmed drug-excipient compatibility. The formulation exhibited sustained drug release over 300 minutes and remained stable under accelerated conditions for 90 days. In vivo, dithranol nanoemulsion gel significantly reduced PASI scores, erythema, and skin thickness compared to controls without causing skin irritation. Discussion: Nanoemulsion-based delivery enhanced the therapeutic efficacy of dithranol by improving transdermal penetration and site-specific drug delivery while minimizing irritation. The gel's physicochemical properties and in vivo performance affirmed its potential for clinical use in psoriasis. Conclusion: Dithranol nanoemulsion gel is a promising formulation for the topical treatment of psoriasis, offering improved stability, bioavailability, patient compliance, and therapeutic outcome.