Formulation and In Vitro Evaluation of a Self-Emulsifying Drug Delivery System of Diclofenac Sodium

Diclofenac sodium is a widely prescribed non-steroidal anti-inflammatory drug (NSAID) used in the management of pain and inflammatory disorders; however, its clinical efficacy after oral administration is limited due to poor aqueous solubility and variable bioavailability. The present study aimed to formulate and evaluate a self-emulsifying drug delivery system (SEDDS) of diclofenac sodium to enhance its solubility, dissolution rate, and in-vitro performance. Suitable oils, surfactants, and co-surfactants were selected based on solubility studies, followed by construction of pseudo-ternary phase diagrams to identify the self-emulsifying region. Optimized SEDDS formulations were evaluated for physicochemical parameters including emulsification efficiency, droplet size, zeta potential, drug content, thermodynamic stability, and in-vitro drug release. The optimized formulation exhibited rapid self-emulsification with nano-sized droplets, good stability, and uniform drug content. In-vitro dissolution studies demonstrated a significantly enhanced drug release profile compared to plain diclofenac sodium. The improved dissolution behaviour is attributed to increased surface area and enhanced solubilization of the drug in gastrointestinal-simulated conditions. The results suggest that SEDDS is a promising and effective lipid-based approach for improving the oral delivery of poorly water-soluble drugs such as diclofenac sodium, with potential to enhance therapeutic efficacy and patient compliance.