长效恩诺沙星注射液体外释药实验及在山羊体内的药动学研究

In Vitro Releasing Assay and Pharmacokinetics in Goats of Long-acting Enrofloxacin Injection

本文比较了恩诺沙星注射剂和长效恩诺沙星注射液体外释药动力学和在山羊体内的药动学特征。采用紫外分光光度法测定了体外释放率;选用8头健康山羊进行肌注长效恩诺沙星注射液和恩诺沙星注射液的药物动力学研究,以反相高效液相色谱法测定血浆中恩诺沙星的浓度。恩诺沙星普通注射液1h体外累计释药百分率达83 22%,而长效恩诺沙星注射液10h释药仅80 56%。肌注长效恩诺沙星注射液和恩诺沙星注射液的药时数据符合一级吸收一室模型,主要药动学参数分别为:T1/2Ka1 76±0 12hand0 34±0 04h(P<0 01);T2/1Ke7 50±0 39hand1 15±0 10h(P<0 01);Tmax4 81±0 26hand0 85±0 09h(P<0 01)。两者的体外释药率和药代动力学参数有显著差异,前者的吸收半衰期、达峰时间及消除半衰期分别为后者的5 2、5 7和6 5倍。说明恩诺沙星注射液肌注后吸收缓慢、消除半衰期延长,具有缓释特征,能起到长效的作用。

The present paper describes in vitro releasing rate and pharmacokinetic properties in goats of long-acting enrofloxacin injection and enrofloxacin injection.In vitro releasing rate was determined by ultraviolet spectrometry and the pharmacokinetics of enrofloxacin was investigated in 8 healthy goats following single intramuscular administration of long-acting enrofloxacin injection and enrofloxacin injection at a dose rate of 20 mg/kg and 2.5 mg/kg,respectively.The concentrations of enrofloxacin in the plasma were determined by reversed-phase HPLC.The enrofloxacin concentration-time data were both described by a one-compartment open model with first-order absorption after single intramuscular administration of the long-acting enrofloxacin injection and enrofloxacin injection.The main pharmacokinetic parameters of the long-acting enrofloxacin injection and enrofloxacin injection were as follows,respectively:T_(1/2 Ka)1.76±0.12 h and 0.34±0.04 h(P<0.01);T_(2/1 Ke)7.50±0.39 h and 1.15±0.10 h(P<0.01);T_(max)4.81±0.26 h and 0.85±0.09 h(P<0.01).The results there were significant differnces in releasing rate in vitro and pharmacokinetics in goats between injections.The T_(1/2 Ka),T_(max),and T_(2/1 Ke) after intramuscular administration of the long-acting enrofloxacin injection were 5.2,5.7 and 6.5 times as large as those after intramuscular administration of the enrofloxacin injection,respectively.These differences indicated that the long-acting enrofloxacin injection was slowly absorbed and has sustained-release and long-acting properties.