Improved Encapsulation and Potential of Liposomal Tosufloxacin via Inclusion in Cyclodextrin
摘要
Liposomal formulation and intratracheal delivery are promising strategies to enhance the therapeutic efficacy of antimicrobial agents. Tosufloxacin (TFLX), a potent fluoroquinolone, faces challenges due to its low aqueous solubility and poor encapsulation efficiency (EE) in liposomes via conventional passive loading. This study aimed to improve TFLX solubility and liposomal loading using hydroxypropyl-β-cyclodextrin (HP-β-CD). A TFLX/HP-β-CD inclusion complex was prepared by optimizing the molar ratio through phase solubility analysis. The complex was incorporated into the aqueous phase of liposomes using the thin-film hydration method. Physicochemical properties, EE, in vitro drug release, and intracellular antibacterial efficacy against Staphylococcus aureus were evaluated. To confirm complex formation, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses were conducted. Complexation with HP-β-CD enhanced TFLX solubility approximately 25-fold. The resulting TFLX/HP-β-CD-liposomes showed a significantly higher EE (69.7 ± 2.4%) compared to conventional liposomes (17.9 ± 0.8%). Drug release from the formulation was sustained for up to 48 h. Intracellular antibacterial assays demonstrated superior efficacy of TFLX/HP-β-CD-liposomes over TFLX-liposomes. FTIR and XRD analyses supported the formation of the inclusion complex through characteristic spectral shifts and reduced crystallinity. The combination of HP-β-CD complexation and liposomal encapsulation markedly improved TFLX solubility, loading efficiency, and intracellular antimicrobial activity. This dual-delivery strategy offers a promising platform for enhancing the formulation of poorly water-soluble antimicrobial agents.
Graphical Abstract