Targeted delivery of levofloxacin-liposomes for the treatment of pulmonary inflammation.

levofloxacin, an amphipathic antibiotic. The aim of the present study was to design passive targeting liposomes, which might improve the antibacterial activity by accumulating in lung and reduce side effects such as neurotoxicity and hematotoxicity associated with direct injection of the drug. Levofloxacin-loaded liposomes were prepared by the ammonium sulfate gradients method. The formulated liposomes were found to be relatively uniform in size (7.424 +/- 0.689 microm) with a positive zeta potential (+13.11 +/- 1.08 mV). The entrapment efficiency of levofloxacin-loaded liposomes ranged from 82.19% to 86.23%. The administered liposomes were composed of soybean phosphatides, cholesterol, levofloxacin, and sulfate which existed in inner liposomes. In vitro drug release was monitored for up to 3 days, and the release behavior was in accordance with the Weibull equation. The levofloxacin-loaded liposomes exhibited a longer elimination half-life (t1/2 beta) in vivo compared with the levofloxacin solution after intravenous injection to New Zealand rabbits. The encapsulation of levofloxacin in liposomes also changed its biodistribution in mice after intravenous injection in caudal vein. Liposomal levofloxacin performed significant lung targeting efficiency with area under the concentration-time curve, targeting efficacy (Te), and The intake rate (Re) of lung, all showing obvious increase. In addition, liposomal formulations presented accumulative activity in spleen and liver. Conversely, the biodistribution of liposomal formulation in non-RES sites, such as kidney, brain, heart, and plasma, decreased with descending peak concentration ration (Ce) compared to levofloxacin injection, which potentially resulted in the reduction of the side effects of free drug. These results indicated that the levofloxacin-loaded liposomes were promising passive targeting to lung for pulmonary infection treatment.