左氧氟沙星聚乳酸-羟基乙酸共聚物纳米微球的制备及性能分析

摘要

BACKGROUND:Conventional formulation of levofloxacin is rapidly and completely metabolized after administration. Fortunately, nanoparticle provides a new way to solve this problem. OBJECTIVE:To prepare a levofloxacin-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticle that can reduce administration frequency, maintain a stable and effective plasma concentration, and also can be combined with tissue-engineered scaffold materials. METHODS:Levofloxacin-loaded PLGA nanoparticles were prepared by emulsion solvent evaporation method. Twenty-four rabbits were taken to investigate the effect of nanoparticle formulation on the pharmacokinetics of levofloxacin and randomized into three groups (n=8 per group): general formulation group received an injection of levofloxacin (20 mg/kg)via ear vein; non-loaded nanoparticle group received an injection of blank nanoparticles; and levofloxaxin-loaded nanoparticle group received an injection of the corresponding levofloxacin-loaded nanoparticles. At different times, blood samples were collected to analyze the drug concentration of levofloxaxin. The antimicrobial activity of the levofloxacin-loaded nanoparticle was evaluated based on the rabbit model of Escherichia coli-induced urinary tract infection. Forty-five New Zealand white rabbits were used to establish urinary tract infection models and randomly divided into three groups (n=15 per group). In negative control group, rabbits received only an injection of normal salinevia ear vein. In conventional formulation group, rabbits received an injection of levofloxacin (20 mg/kg). In nanoparticle group, rabbits received an injection of the corresponding levofloxacin nanoparticles. Subsequently, blood samples were obtained, and white blood cell (WBC) count and neutrophil percentage was tested; at the same time, the middle segment morning urine was collected to detect bacteriuria and urine WBC positive rates. At 9 days, the histopathologic analysis of the bladder mucosa was done. RESULTS AND CONCLUSION:(1)In vivo the pharmacokinetics: Compared with the conventional formulation group, the ideal levofloxacin-loaded PLGA nanoparticles prepared under optimal conditions significantly reduced the fluctuations in plasma concentration and frequency of administration. (2) Antimicrobial activity:Escherichia coli-induced urinary tract infection was gradualy in control in the conventional formulation group and levofloxacin-loaded PLGA nanoparticle group, and basically cured at 9 days after injection. In addition, the number of cured patients was basically higher in the levofloxacin-loaded PLGA nanoparticle group than the conventional formulation group at the same time point, but there was a significant difference between the two groups only at 5 days after treatment. It can be concluded that levofloxacin-PLGA nanoparticles provide a well-sustained delivery system for treatment or prevention of urinary tract infections and provide a foundation for further investigations on tissue-engineered urethral reconstruction.%背景:普通剂型的左氧氟沙星在体内代谢快,半衰期短,纳米微球为解决这一问题提供了新的途径.目的:制备一种能够减少给药次数,维持平稳有效的血药浓度且能复合在组织工程支架材料上的左氧氟沙星聚乳酸-羟基乙酸共聚物[poly(lactic-co-glycolic acid),PLGA]纳米微球.方法:采用乳化溶剂挥发法制备不同条件下的左氧氟沙星纳米微球.①取24只新西兰大白兔随机分为3组研究左氧氟沙星纳米微球的体内药代动力学特性,普通剂型组通过耳缘静脉注射普通剂型的左氧氟沙星注射液20 mg/kg,未载药纳米微球组接受等剂量的未载药纳米微球,载药纳米微球组接受等剂量的左氧氟沙星纳米微球,每组8只.于定点时间测定静脉血中左氧氟沙星含量;②取45只新西兰大白兔建立尿路感染模型,随机分为3组,空白对照组每日经耳缘静脉注入生理盐水;传统剂型组注入普通剂型的左氧氟沙星(20 mg/kg);纳米微球组注入相应等剂量的左氧氟沙星纳米微球.于不同时间点行尿细菌培养,检测尿白细胞、血白细胞和中性粒细胞数;9 d后行膀胱组织学检测评估左氧氟沙星纳米微球抗菌能力.结果与结论:①体内药代动力学特性:与传统剂型相比,最优条件下的左氧氟沙星PLGA纳米微球可以明显减少血药浓度的波动和给药频率;②抗菌性能评估:在每日用药的传统剂型组和仅一次给药的纳米微球组,兔感染症状逐步得到控制,在第9天时已基本治愈;此外,在相同时间点纳米微球组兔治愈数量基本高于传统剂型组,虽然只有在用药后的第5天两组之间差异有显著性意义;③结果表明:左氧氟沙星PLGA纳米微球抗感染能力强,缓释性能佳,能明显减少给药频次及延长作用时间,在治疗泌尿系统感染方面具有良好的临床和组织工程尿道应用前景.