Comparison of ELISA and LC鈥揗S/MS for the Measurement of Flunixin Plasma Concentrations in Beef Cattle after Intravenous and Subcutaneous Administration
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- 作者：Weilin L. Shelver ; Lisa A. Tell ; Sarah Wagner ; Scott E. Wetzlich ; Ronald E. Baynes ; Jim E. Riviere ; David J. Smith
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2013
- 出版时间：March 20, 2013
- 年：2013
- 卷：61
- 期：11
- 页码：2679-2686
- 全文大小：292K
- 年卷期：v.61,no.11(March 20, 2013)
- ISSN：1520-5118
文摘
Eight cattle (288 卤 22 kg) were treated with 2.2 mg/kg of body weight of flunixin free acid in a crossover design by subcutaneous (SC) and intravenous (IV) administration. After a minimum 1:10 dilution with 50 mM phosphate buffer, a commercial immunoassay was adapted to determine plasma concentrations of flunixin. The limit of detection was 0.42 ng/mL and the working range was 0.76鈥?6.4 ng/mL when adjusted with the dilution factor. Plasma samples were extracted using mixed-mode cation exchange solid phase extraction prior to the LC鈥揗S/MS analyses. The linear calibration curve for LC鈥揗S/MS was 0.5鈥?000 ng/mL with a limit of detection of 0.1 ng/mL for flunixin and 0.3 ng/mL for 5-hydroxy flunixin. Flunixin concentrations determined using the ELISAs were compared to concentrations derived from the same samples using LC鈥揗S/MS analyses. Pharmacokinetic parameters of time versus concentration data from each analysis were estimated and compared. Differences (P < 0.05) in estimates of area under the curve, volume of distribution, and clearance were apparent between ELISA and LC鈥揗S/MS analyses after IV dosing; after SC dosing, however, there were no differences among the estimated parameters between the two methods. Quantitative immunoassay was a satisfactory method of flunixin analysis and that it would be difficult to differentiate routes of administration in healthy beef cattle based on the plasma elimination profile of flunixin after IV or SC administration.