Determination of Intracellular Concentrations of Free and Two Types of Liposome-Encapsulated Enrofloxacin in Anatolian Shepherd Dog Monocytes

In this study, it was evaluated the accumulation of free and two types of liposome-encapsulated enrofloxacin (LEE) at the doses of 0.25, 0.5 and 1 mu g/ml, which were clinically relevant concentrations into monocytes of healthy Anatolian shepherd dogs. Enrofloxacin was encapsulated with two different types of liposome in multilamellar large vesicles (MLV). Type A MLV composed of 15 mg egg phosphatidylcholine and 35 mg cholesterol, Type B MLV composed of phosphatidylcholine (PC), cholesterol and enrofloxacin, in a molar ratio of 1 : 1 : 1. The mean sizes of Type A and Type B liposome were found to be 7.65 and 4.27 mu m, respectively. However, the mean encapsulation rate determined of Type A (13 +/- 2%) was found lower than Type B liposome (44 +/- 3%). The amounts of intracellular enrofloxacin concentrations were determined by high performance liquid chromatography. Type B LEE accumulated significantly higher level into monocytes when compared to free drug or Type A liposome. This study showed that Type B LEE markedly concentrated within monocytes and may improve the antibacterial efficacy of the antibiotic.