OBJECTIVETo prepare sparfloxcain lactate (SPLX) loaded liposomes and study its corneal penetration and bacterial inhibitory in vitro.

METHODSLiposomal 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.

RESULTSThe 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.

CONCLUSIONThe pH gradient technique is suitable for preparing SPLX liposomes, which can improve the transcorneal penetration and antibacterial activity of SPLX in vitro.