Formulation And Evaluation of Diclofenac Sodium-Loaded Self-Microemulsifying Gel for Enhanced Topical Drug Delivery

Abstract

Objective: This study aimed to develop a topical gel formulation of diclofenac sodium (DFS) utilizing a self-micro emulsifying drug delivery system (SMEDDS) to enhance solubility, bioavailability, and patient compliance while minimizing systemic side effects associated with oral administration. Methods: DFS solubility was evaluated in various oils, surfactants, and co-surfactants. A pseudo-ternary phase diagram guided the selection of optimal SMEDDS components. The SMEDDS formulation, comprising cinnamon oil, Tween 20, and propylene glycol, was converted into a gel using Carbopol 940. Both the liquid SMEDDS and gel underwent extensive physicochemical characterization, including drug content, pH, viscosity, spreadability, and in vitro/ex vivo diffusion studies. Key Findings: Cinnamon oil, Tween 20, and propylene glycol exhibited the highest DFS solubility and emulsification efficiency. The optimized SMEDDS formulation showed robust stability, rapid self-emulsification, high drug loading, and favorable droplet size (112.8 nm) and zeta potential (-11.36 mV). The gel demonstrated consistent drug release (79.70% over 1440 minutes) and improved skin permeation (71.30% over 1440 minutes). Conclusions: The DFS-loaded SMEDDS gel formulation significantly enhances the solubility, dissolution, and topical bioavailability of DFS, providing a promising alternative for managing arthritic pain and inflammation with reduced systemic side effects.