|Tell, Lisa - University Of California|
|Wagner, Sarah - North Dakota State University|
|Wetzlich, Scott - University Of California|
|Baynes, Ronald - North Carolina State University|
|Riviere, Jim - Kansas State University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/2/2013
Publication Date: 8/26/2013
Citation: Shelver, W.L., Tell, L.A., Wagner, S., Wetzlich, S.E., Baynes, R.E., Riviere, J.E., Smith, D.J. 2013. Comparison of ELISA and LC-MS/MS for the measurement of flunixin plasma concentrations in beef cattle after intravenous and subcutaneous administration [abstract]. Association of Analytical Communities Annual Meeting & Exposition. Poster No. P-M-047.
Technical Abstract: Eight cattle (288 +/- 22 kg) were treated with 2.2 mg/kg of flunixin in a cross-over design using subcutaneous (SC) and intravenous (IV) administration. The limit of detection (LOD) was 0.42 ng/mL and the working range was 0.76 - 66.4 ng/mL for ELISA when adjusted for dilution. The linear calibration curve for LC-MS/MS was 0.5 – 2000 ng/mL with a LOD of 0.1 ng/mL for flunixin and 0.3 ng/mL for 5-OH flunixin. Pharmacokinetic parameters of time vs. concentration data from ELISA and LC-MS/MS 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-MS/MS analyses after IV dosing but not with SC dosing. Nevertheless, it would be difficult to differentiate routes of administration in healthy cattle based on the plasma elimination profiles of flunixin after IV or SC dosing.