QBD-Based Development and Optimization of an Oral Microemulsion of Vilazodone Hydrochloride for Enhanced Solubilization and Dissolution

Abstract

Vilazodone hydrochloride is a serotonin partial agonist-reuptake inhibitor widely used for the treatment of major depressive disorder (MDD). Despite its clinical efficacy, its poor aqueous solubility and dissolution characteristics may limit oral drug performance and contribute to variability in absorption. Development of lipid-based delivery systems such as microemulsions offers a promising strategy for improving the solubilization and dissolution behavior of poorly water-soluble drugs.[1] The application of a Quality by Design (QbD) approach enables systematic formulation development through identification and control of critical formulation variables. Solubility screening was performed to select suitable oils, surfactants, and co-surfactants for maximum drug solubilization. Pseudo-ternary phase diagrams were constructed to identify microemulsion regions. Quality risk assessment was employed to define critical material attributes (CMAs) and critical quality attributes (CQAs). A Design of Experiments (DoE)-based optimization strategy was applied to investigate the effects of oil concentration, surfactant/co-surfactant ratio, and aqueous phase content on formulation characteristics.[2] The optimized microemulsion was evaluated for globule size, polydispersity index (PDI), zeta potential, drug content, transmittance, viscosity, dilution robustness, thermodynamic stability, and in-vitro dissolution performance. The optimized microemulsion exhibited nanosized droplets with narrow size distribution and high drug incorporation efficiency. The formulation demonstrated excellent physical stability, transparency, and robustness upon dilution. Enhanced drug solubilization and significantly improved in-vitro dissolution were achieved compared with the pure drug and conventional formulations. The QbD framework facilitated identification of the design space and established a reproducible and robust formulation process. QbD-based development of an oral vilazodone hydrochloride microemulsion represents a promising strategy for overcoming dissolution-related limitations associated with this poorly water-soluble drug. The optimized microemulsion has the potential to improve oral drug performance and may contribute to enhanced bioavailability and therapeutic effectiveness in the management of major depressive disorder.[3] Keywords: Vilazodone Hydrochloride; Microemulsion; Quality by Design (QbD); Design of Experiments; Solubilization; Dissolution Enhancement; Oral Drug Delivery; Major Depressive Disorder