Development, Optimization and Characterization of Quercetin-Loaded Nanoemulsion: A Pharmaceutical Formulation Approach

Abstract

Quercetin is a naturally occurring flavonoid with considerable pharmaceutical and biological importance. Despite its promising pharmacological properties, its formulation into conventional dosage forms is challenging because of its poor aqueous solubility and limited dissolution characteristics. The present study was undertaken to develop and optimize a quercetin-loaded nanoemulsion to improve its solubilization and provide a stable nanosized delivery system. Preformulation studies were performed to determine the solubility of quercetin in different oils, surfactants and co-surfactants. A pseudo-ternary phase diagram was constructed to identify a suitable nanoemulsion region. Capmul MCM was selected as the oil phase, Tween 80 as surfactant and Transcutol P as co-surfactant. Nanoemulsions were prepared by aqueous phase titration followed by probe sonication. A three-factor, three-level design was employed to optimize the formulation, with droplet size, polydispersity index, zeta potential and entrapment efficiency considered as critical quality attributes. The optimized formulation demonstrated a droplet size of 116.1 ± 1.22 nm, zeta potential of −28.6 ± 0.78 mV and entrapment efficiency of 93.8 ± 1.18%. Transmission electron microscopy showed predominantly spherical and smooth droplets. In-vitro release studies demonstrated controlled quercetin release up to 12 h, with 91.7 ± 1.56% cumulative release from the optimized formulation. The results demonstrate that nanoemulsion technology is an effective approach for formulating quercetin into a nanosized pharmaceutical delivery system with improved physicochemical characteristics and controlled drug release.