Szuna A J, Blain R W
Department of Drug Metabolism and Pharmacokinetics, Hoffmann-La Roche, Nutley, NJ 07110.
J Chromatogr. 1993 Oct 29;620(2):211-6. doi: 10.1016/0378-4347(93)80006-p.
Analysis of a new antibacterial agent, Ro 23-9424 (I), in plasma has been complicated by the fact that its metabolite, fleroxacin (II), is formed not only in vivo, but also nonenzymatically by the hydrolysis of the ester bond of I. In order to minimize sample preparation time and possible hydrolysis during sample preparation, a high-performance liquid chromatographic procedure was developed which features direct injection of plasma and multidimensional chromatography. The first dimension size-exclusion separation allows plasma proteins to elute with the column void volume. The second dimension reversed-phase column provides a high-resolution separation dependent upon the hydrophobicity of the sample species. With a 5-microliters injection, the limit of quantitation of the method is 0.35 microgram/ml for I and 0.27 microgram/ml for II. The method was used to determine steady state plasma vs. time profiles for I and II from 750 mg i.v. doses of I administered twice daily.
新型抗菌剂Ro 23 - 9424（I）的血浆分析工作因以下事实而变得复杂：其代谢物氟罗沙星（II）不仅在体内形成，还会通过I的酯键非酶水解产生。为了尽量减少样品制备时间以及样品制备过程中可能出现的水解现象，开发了一种高效液相色谱方法，该方法的特点是直接进样血浆并采用多维色谱法。第一维尺寸排阻分离可使血浆蛋白随柱空体积洗脱。第二维反相柱则根据样品物质的疏水性实现高分辨率分离。进样5微升时，该方法对I的定量限为0.35微克/毫升，对II的定量限为0.27微克/毫升。该方法用于测定每日两次静脉注射750毫克I后I和II的稳态血浆浓度随时间变化的曲线。
