Quality-by-Design Approach Development, Characterization, and In Vitro Release Mechanism Elucidation of Nanostructured Lipid Carriers for Quetiapine Fumarate Oral Delivery

The objective of this work was to develop a new nanostructured lipid carrier (NLC) formulation for the oral delivery of quetiapine fumarate (QTF) and assess the drug’s in vitro release mechanism through gastric and intestinal conditions. A preformulation study was conducted to select the most suitable components and solid-to-liquid lipid ratio for the formulation of nanoparticles. Then, a central composite design was employed to optimize the development of NLC and to study the effect of lipid and surfactant percentages on the physical characteristics of the preparation. The optimal formulation was subjected to physicochemical characterization and stability study. An in vitro release assay using simulated gastrointestinal fluids was performed to study the QTF release mechanism. The optimal formulation showed good particle size, PDI, and zeta potential of 179.2 ± 2.6 nm, 0.220 ± 0.020, and −33.63 ± 0.23 mV, respectively. The encapsulation efficiency and the loading capacity were 84.49 ± 1.25% and 2.6 ± 0.03%, respectively. DSC and FTIR analysis showed compatibility between QTF and other components of the formulation and successful encapsulation of the drug within lipid nanoparticles. The optimal formulation also showed good long-term stability at 4 °C storage temperature. The in vitro release of QTF followed the Korsmeyer-Peppas model. The study demonstrated that QTF was mainly released by diffusion mechanism in the gastric medium, and by erosion and anomalous transport in the intestinal medium. NLC represents a suitable formulation for the oral delivery of QTF. Further studies should investigate the oral absorption and lymphatic transport potential of the optimized formulation.