Formulation Development and In-Vitro Assessment of Rilpivirine Nanobilosomes

This study focused on the preparation and characterization of rilpivirine-loaded nanobilosomes. Formulations were developed using rilpivirine, phosphatidylcholine S-100 (SPC), and sodium deoxycholate (SDC) via the thin film hydration method. The nanobilosomes were characterized for vesicle size, polydispersity index (PDI), surface charge, and entrapment efficiency (%EE). Thermal behavior and drug-excipient interactions were analyzed using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM) revealed that BS-06 nanobilosomes possess a smooth and uniform surface morphology. In vitro cytotoxicity assays were conducted on HeLa and HEK 293 cell lines, and minimum inhibitory concentration (MIC) was assessed against S. aureus and E. coli. Stability was monitored over 3 months at various temperatures. The optimized formulation (BS-06) exhibited a vesicle size of 132.8 ± 4.0 nm, a zeta potential of -30.10 ± 0.8 mV, and a PDI of 0.20, demonstrating optimal surface characteristics and maximum entrapment efficiency. In vitro release studies indicated a maximum drug release of 84.81 ± 4.6% over 24 h. Cytotoxicity studies showed that BS-06 improved cell viability in HeLa and HEK 293 cell lines at 24 and 48 h and enhanced antibacterial activity against S. aureus and E. coli. Overall, our findings highlight the potential of rilpivirine-loaded nanobilosomes as a promising drug delivery system for HIV/AIDS, with enhanced dissolution, stability and biocompatibility.