万古霉素在正常兔眼和细菌性眼内炎兔眼内的药代动力学研究

Study on pharmacokinetic of vancomycin in normal and endophthalmitis eyes in rabbit

背景万古霉素近年来常被作为金黄色葡萄球菌性眼内炎治疗的首选药物，万古霉素在眼内药代动力学的研究报道较少。目的观察万古霉素在正常兔眼和细菌性眼内炎兔眼房水、玻璃体及血清中质量浓度的变化，并进行药代动力学参数比较。方法选取健康成年兔72只，采用随机数字表法分为正常组和眼内炎组，每组36只。眼内炎组兔右眼玻璃体腔内接种2000CFU／ml金黄色葡萄球菌建立眼内炎模型，注射后72h待出现典型的眼内炎表现时，兔眼玻璃体腔内注射10g／L万古霉素注射液0．1ml，分别于注射后0．5、2、4、6、12、24、48、72、84h经兔耳缘静脉采血2ml，之后以空气栓塞法处死动物，摘除眼球，收集房水和玻璃体，利用高效液相色谱仪紫外（HPLC—UV）法检测万古霉素在血液、房水和玻璃体内的质量浓度。3p97药代动力学软件拟合药代动力学参数。结果HPLC法的准确度和精确度符合生物样品的检测要求。玻璃体腔内注射万古霉素后，其在正常兔眼内的代谢呈二室模型，拟合曲线的高峰质量浓度Cmax分别为50．16mg／L和751．42mg／L，t1/2为51．04h和53．21h；其在金黄色葡萄球菌性眼内炎兔眼中代谢呈一室模型，高峰质量浓度Cmax分别为24．94mg／L和687．66mg／L，t1/2分别为11．42h和12．91h，2组动物血药质量浓度均较低，差异无统计学意义（P〉0．05）。正常组和眼内炎组玻璃体腔内注射万古霉素后随时间延长，玻璃体中万古霉素的质量浓度逐渐下降，而房水中出现先升高后下降的趋势。与正常组相应时间点比较，眼内炎组玻璃体和房水中万古霉素的质量浓度均明显下降，差异均有统计学意义（P〈0．05，P〈0．01）。结论HPLC能满足万古霉素药代动力学分析的需要；万古霉素在正常兔眼内的质量浓度较高，清除缓慢，而在细菌性眼内炎兔眼中质量浓度较低、清除较快。

Background Vancomycin has been increasingly recommended for the management of endophthalmitis,but few research report has been published about the pharmacokinetics of intravitreal vancomycin up to now. It is necessary to have an exact method to measure the concentration of vancomycin in animal eyes after intravitreal injection. Objective This study was to observe and compare the phamacokinetical process of vancomycin in serum,vitreous and aqueous humor between normal and infected rabbit eyes. Methods Seventy-two healthy adult rabbits were randomly divided into normal group and infected group and 36 rabbits for each. The animal models of endophthalmitis were established by intravitreal inoculation of 2000 CFU/ml staphylococcus aureus in the right eyes of rabbits in the infected group. Once endophthalmitis developed,0. 1 ml vancomycin （10 g/L） solution was injected into the vitreous of every rabbit. The peripheral blood, vitreous and aqueous humor samples were respectively collected in 4 rabbits for each group at 0.5,2,4,6,12,24,48,72 and 84 hours after injection for detection of vancomycin concentration by high performance liquid chromatography（HPLC-UV）. 3p97 software was used to create fit parameters of pharmacokinetics. This experiment followed the Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission （Version 1988）. Results The accuracy of HPLC fitted the detecting request of biological specimen. The concentration-time data of vancomycin in normal rabbit aqueous humor and vitreous was subject to two-compartment model. The pharmacokinetic parameters were separately as following： Cmax was 50. 16 mg/L and 751.42 mg/L, t1/2 was 51.04 hours and 53.21 hours. The concentration-time data of vancomycin in infected rabbit aqueous humor and vitreous was subject to one-compartment model. The pharmacokinetic parameters were separately as following： Cmax was 24.94 mg/L and 687.66 mg/L, t1/2was 11.42 hours and 12.91 hours. The concentration of vancomycin in serum was much lower and almost undectable. The concentration of vancomycin in vitreous was gradually reduced as the prolong of time after injection in both normal group and infected group, but a obvious decline after increased level was seen in aqueous humor. Compared with normal group,the concentrations of varlcomycin in both vitreous and aqueous humor were reduced at various time points（P〈0.05,P〈0.01 ）. Conclusions HPLC is simple,highly sensitive and specific for the pharmacokinetic analysis of vancomycon. These results indicate that pharmacokinetic parameters of vancomycin alter in pathological condition,which is helpful for us to establish the better treatment guidelines for endophthalmitis.