[Preparation of liposomal sparfloxcain lactate and its corneal penetration and antibacterial activity in vitro].

Objective: To prepare sparfloxcain lactate (SPLX) loaded liposomes and study its corneal penetration and bacterial inhibitory in vitro.
Methods: Liposomal SPLX (mass ratio of phospholipids/ cholesterol/drug at 18:6:1) was prepared by pH-gradients. The transcorneal penetration experiments of liposomal SPLX were performed in modified Franz's cells with the rabbit's corneal. The concentration of SPLX was determined by high-performance liquid chromatography. The penetration parameters were calculated. The in vitro antibacterial activities on S. aureus, P. aeruginusa, E. coli, and B. subtilis were determined by two fold dilutions.
Results: The entrapment efficiency of SPLX in the liposomes by pH-gradients was (81.61 +/- 1.98)%, which was significantly higher than that by film dispersion method (11.48 +/- 0.86)% and reverse evaporating method (18.64 +/- 1.05)% (both P < 0.01). The permeability coefficient and corneal deposition quantity of SPLX liposomes were 1.65- and 4.98-folds higher as compared with those of free drug solutions. The minimal inhibitory concentrations (MICs) of liposomal SPLX against S. aureus, P. aeruginosa, E. coli, and B. subtilis were 1/4, 1/2, 1/1, 1/17 times lower than those of free drug, respectively, and the minimal bactericide concentrations (MBCs) were 1/4, 1/2, 1/1, 1/4 times lower than those. In addition, the time-kill values of liposomal SPLX were better than those of free.
Conclusion: The pH gradient technique is suitable for preparing SPLX liposomes, which can improve the transcorneal penetration and antibacterial activity of SPLX in vitro.