See discussions, stats, and author profiles for this publication at: Simultaneous Determination of Pantoprazole and Its Two Metabolites in Dog Plasma by HPLC Article in Journal of chromatographic science · May 2005 DOI: 10.1093/chromsci/43.5.271 · Source: PubMed CITATIONS 10 READS 101 4 authors , including: Some of the authors of this publication are also working on these related projects: CYP2C9 AND CYP2C19 View project ADME study of Scutellarin View project Fengdan Jin Yan Shan University 4 PUBLICATIONS 43 CITATIONS SEE PROFILE Dafang Zhong Chinese Academy of Sciences 366 PUBLICATIONS 5,384 CITATIONS SEE PROFILE All content following this page was uploaded by Dafang Zhong on 22 August 2015. The user has requested enhancement of the downloaded file.
A simple and sensitive high-performance liquid chromatography (HPLC) method is developed and validated for simultaneous determination of pantoprazole and its two metabolites (pantoprazole sulfone and pantoprazole thioether) in dog plasma and applied to a pharmacokinetic study in Beagle dogs. Following a protein precipitation procedure, the samples are separated using reversed-phase HPLC (C 18 ) by a gradient of acetonitrile and ammonium acetate (pH 6.0) at a flow rate of 1.0 mL/min and quantitated using UV detection at 290 nm. Omeprazole is selected as the internal standard. The method has a lower limit of quantitation of 0.025 μg/mL for pantoprazole and its two metabolites, using 0.1-mL aliquots of plasma. The linear calibration curves are obtained in the concentration range of 0.025–10.0 μg/mL for three analytes. The intra- and interrun precision (relative standard deviation), calculated from quality control (QC) samples, is less than 13% for three analytes. The accuracy determined from QC samples is between –6.4% and 12%. Introduction Pantoprazole (PAN) (Figure 1), a selective and long-acting proton pump inhibitor (1), is used in the treatment of acid- related gastrointestinal disorders such as duodenal and gastric ulcers, reflux esophagitis, and Zollinger–Ellison syndrome (2). Drugs with sulfoxide moieties, such as omeprazole (3), lanso- prazole (4), and PAN, can undergo oxidative metabolism by c y t o c h rome P450 or flavin containing monooxygenase (or both) (5,6) and can undergo reductive metabolism by alde- hyde oxidase or thioredoxin-linked enzymes (or both) (7). Both liver and gut flora are potential sites for formation of the sul- fide metabolite (5–7). These metabolites include pantoprazole sulfone (PAN-SO 2 ), pantoprazole thioether (PAN-S), demethy- lated PAN-SO 2 , and demethylated PAN-S. In order to eluci- date the pharmacokinetics of PAN and its metabolites after administration of PAN to animals, it is essential to develop a method to determine the concentration of PAN and its metabo- lites in biological fluids. Several high-perf o rmance liquid chro- matographic (HPLC) methods have been available for the determination of PAN and its metabolites in biological fluids (8–12). Although three HPLC methods (8–10) have enabled PAN and PAN-SO 2 to be determined in plasma or serum, these methods do not determine PAN-S. Furt h e rmore, two methods