Preparation Of Lung Targeting Liposomes Rifampin And Distribution In Tissues Of Mice

Preparation of Lung Targeting Liposomes Rifampin and Distribution in Various Tissues of Mice Chen Wei Directed by Prof. Han Wenyu Prof. Chen Chuangfu ABSTRACT Liposomes RFP (Lip-REP) were prepared by thin film dispersing method. The effects of different variables on the preparation of Lip-RFP were studied. The optimized preparation conditions of Lip-REP were aquired through uniform and orthogonal test. Liposomes REP respectively containing 10% D-mannose(Lip-RFP-Man) , D-glucose and mannitol were prepared by the same method as the preparation of Lip-RFP and 3.0 g monosaccharide was saluted into 30 ml phosphate-buffered saline (PBS, pH7.4) when the Liposomes REP with monosaccharides were prepared. The comparisons of lung targeting action among three liposomes REP containing D-mannose , D-glucose and mannitol were carried out by microbiological assay. The drug release properties of Lip-REP-Man were studied in vitro by a dialysis system and physiological saline solution was used as release medium. MICs and MBCs of free- and liposome-incorporated REP against several bacteria were determined by tube double dilution test and were compared between free and liposomal RFP. The bactericidal tests of Lip-REP and Lip-RFP-Man in vivo were studied through plate dilution. The Iiposomal entrapment efficiency of the Lip-REP and Lip-RFP-Man were determined by dialysis method. The distribution of Lip-RFP , Lip- REP-Man and free drug was investigated in various tissues of mice by microbiological assay respectively. The levels and distribution of RFP activity in tissue after intravenous administration Lip-REP, Lip-REP-Man and free RFP was explored. The concentrations of RFP in serum and visceral organs were measured as follows. Visceral organs (heart, liver, spleen, lungs and kidneys) were homogenized in 2.0 ml of physiological saline per g, using a glass homogenizer, and then centrifuged at 3000r min?for 20 mm. A paper disk (8 mm in diameter) was immersed in the resultant supematant or serum, and the disk was 45 placed on a LB agar plate prepared by containing Ca. 5 X I 0~ spores of Bacillus subtilis (as an indicator bacterium) per ml. After overnight culture at 37C, the concentration of RFP in the test solution was determined from the diameter of the resulting growth inhibition zone, using standard semilog plots of the agent at known concentration. REP standards were prepared in PBS. The results showed that the optimized preparation conditions of Lip-REP was as follow: temperature which evaporated rotately chloroform was 35 C emulsif~抜ng temperature was 20 慍: the ratio to volume of chloroform and PBS was 1:5; the proportion of RFP and lipids in weight was 1:7; stirring rate was 400 r~ min?for 0.5h to I h. The diameter of Lip-RFP-Man which was prepared under above conditions ranged from Ito 10 pin and the diameter of 82.4% of the Lip-RFP-Man was in the range of 2.5 to 10 jim The extent of entrapment of the Lip-RFP and Lip-RFP-Man was 46.8% and 48.3% respectively. The results of in vitro drug release demonstrated that the Lip-REP- Man possessed a sustained release property which accorded with Higuchi抯 equation: Y~=0.2239t?-O.3046(r拁O.96 13). The results of bacteria inhibition in vitro indicated that MICs of liposo...