In Vitro Release of Diclofenac From Synthetic Fatty Bases; Effect of Surfactants

ABSTRACT Diclofenac sodium is widely used for its analgesic and anti‐inflammatory properties. Despite its poor solubility, diclofenac's high permeability and rectal administration via suppositories provide a rapid onset of action, bypassing first‐pass metabolism. However, fatty bases commonly used in suppository formulation pose challenges in drug release due to poor dispersibility. This study investigates the effect of incorporating non‐ionic surfactants, Polysorbate 80 and Glyceryl Monostearate, at varying concentrations (1%–2%) on the drug release properties of diclofenac sodium suppositories prepared using three fatty bases (S, W, and ST). Suppositories were formulated using the fusion method, and their physicochemical properties, including hardness, melting range, disintegration time, and uniformity, were evaluated. Drug release profiles were analyzed through in vitro dissolution studies. Results showed that surfactants significantly enhanced drug release compared to formulations without surfactants, with Polysorbate 80 demonstrating a concentration‐dependent effect. While low to moderate concentrations of Polysorbate 80 and GMS improved drug release, higher concentrations led to a decrease, potentially due to micelle entrapment. This study demonstrates that Polysorbate 80 and glyceryl monostearate at approximately 1.25% can optimize diclofenac release from fatty‐based suppositories without compromising physicochemical integrity. These findings suggest a cost‐effective alternative to advanced analgesic delivery systems for postoperative pain management.