Nanosized Bilosomes as a Potential Platform for Improved Therapeutic Efficacy of Capecitabine Against Colon Cancer in Rats: Formulation, Evaluation, and Optimization

Background/Objectives: Colorectal cancer is a leading cause of global cancer-related mortality. Capecitabine, a 5-fluorouracil prodrug, effectively targets colorectal cancer but suffers from an extremely short half-life, requiring frequent administration. Bilosomes (membrane-stabilized bile salts) are vesicular systems that improve gastrointestinal stability, prevent drug leakage, and extend residence time. This study aimed to fabricate and characterize capecitabine-loaded nanosized bilosomes to overcome the pharmacokinetic limitations and systemic toxicities of conventional capecitabine therapy. By leveraging bile salt-stabilized vesicular systems, we seek to provide sustained capecitabine release, improve gastrointestinal permeability, and enhance therapeutic efficacy against colorectal cancer. We also assessed the anticancer potential of capecitabine-loaded nanosized bilosomes by measuring diagnostic and prognostic biomarkers, including cancer embryonic antigen, carbohydrate antigen 19.9, matrix metalloproteinase-9, and vascular endothelial growth factor A, to evaluate their impact on tumor progression, extracellular matrix degradation, and angiogenesis. Methods: In a 32 full factorial design, nine capecitabine-loaded bilosomes were generated utilizing a central composite design within the framework of response surface methodology. Entrapment efficiency, in vitro drug release and its kinetics, vesicle size, zeta potential, and their kinetics were evaluated. The optimized capecitabine-loaded nanosized bilosomes formulation was subjected to further investigations, such as Fourier transform infra-red spectroscopy, differential scanning calorimetry, X-ray diffractometry study, stability studies, pharmacokinetic study, and in vivo studies, including detection of matrix metalloproteinase-9 and vascular endothelial growth factor A by Real-Time polymerase chain reaction, evaluation of colon biomarker, and examination of colon tissue through histopathology. Results: The prepared capecitabine-loaded bilosomes were nanosized spheres with suitable entrapment efficiency and a high zeta potential. After treatment with capecitabine-loaded bilosomes, the data collected from living organisms indicated a notable reduction in the serum values of carbohydrate antigen 19.9 and cancer embryonic antigen, gene expression values of matrix metalloproteinase-9 and vascular endothelial growth factor A. Histopathological study showed almost complete restoration of colonic features with a lesser extent of epithelial lining and crypt dysplasia. Conclusions: The present study findings demonstrate that capecitabine-loaded bilosomes possess high anti-tumor activity against colorectal cancer.