DESIGN, OPTIMIZATION, AND EVALUATION OF A POLYHERBAL EXTRACT CURCUMA LONGA AND BOSWELLIA SERRATA LOADED TRANSDERMAL PATCH FOR ANTI-INFLAMMATORY ACTIVITY: IN VITRO RELEASE, EX VIVO SKIN PERMEATION, AND CELLULAR ANTI-INFLAMMATORY ASSESSMENT

Abstract

The present study focused on the design, optimization, and evaluation of a polyherbal extract-loaded transdermal patch for anti-inflammatory application using a systematic formulation approach. Hydroalcoholic extracts of Curcuma longa and Boswellia serrata were combined in a 1:1 ratio and incorporated into transdermal patches prepared by the solvent casting method using hydroxypropyl methylcellulose and ethyl cellulose as film-forming polymers. A Box–Behnken design was employed to optimize formulation variables, including polymer ratio, plasticizer concentration, and permeation enhancer level. The optimized formulation exhibited desirable physicochemical properties, including uniform thickness, high folding endurance, and satisfactory drug content. In vitro drug release studies demonstrated sustained release over 24 hours, following non-Fickian diffusion kinetics. Ex vivo permeation studies using rat skin revealed a significant enhancement in drug permeation, with a 2.3-fold increase in flux compared to the control, along with reduced lag time. The optimized patch also showed higher skin retention, indicating the formation of a local drug reservoir. In vitro anti-inflammatory evaluation using LPS-stimulated RAW 264.7 macrophages demonstrated significant inhibition of nitric oxide and reactive oxygen species without cytotoxicity. Stability studies confirmed the robustness of the formulation under accelerated conditions. Overall, the developed transdermal system offers a promising phytopharmaceutical approach for sustained and effective anti-inflammatory therapy.