Plasma and urine pharmacokinetics of intravenously administered flunixin in greyhound dogs

Morris, Tim; Paine, Stuart W.; Zahra, Paul; Li, Eric; Colgan, Sally; Karamatic, Steven

Abstract

© 2019 John Wiley & Sons Ltd Medication control in greyhound racing requires information from administration studies that measure drug levels in the urine as well as plasma, with time points that extend into the terminal phase of excretion. To characterize the plasma and the urinary pharmacokinetics of flunixin and enable regulatory advice for greyhound racing in respect of both medication and residue control limits, flunixin meglumine was administered intravenously on one occasion to six different greyhounds at the label dose of 1mg/kg and the levels of flunixin were measured in plasma for up to 96hr and in urine for up to 120hr. Using the standard methodology for medication control, the irrelevant plasma concentration was determined as 1ng/ml and the irrelevant urine concentration was determined as 30ng/ml. This information can be used by regulators to determine a screening limit, detection time and a residue limit. The greyhounds with the highest average urine pH had far greater flunixin exposure compared with the greyhounds that had the lowest. This is entirely consistent with the extent of ionization predicted by the Henderson–Hasselbalch equation. This variability in the urine pharmacokinetics reduces with time, and at 72hr postadministration, in the terminal phase, the variability in urine and plasma flunixin concentrations are similar and should not affect medication control.

Citation

Morris, T., Paine, S. W., Zahra, P., Li, E., Colgan, S., & Karamatic, S. (2019). Plasma and urine pharmacokinetics of intravenously administered flunixin in greyhound dogs. Journal of Veterinary Pharmacology and Therapeutics, 42(5), 505-510. https://doi.org/10.1111/jvp.12775

• Journal Article Type: Article
• Acceptance Date: Apr 18, 2019
• Online Publication Date: May 14, 2019
• Publication Date: 2019-09
• Deposit Date: May 28, 2019
• Publicly Available Date: May 15, 2020
• Journal: Journal of Veterinary Pharmacology and Therapeutics
• Print ISSN: 0140-7783
• Electronic ISSN: 1365-2885
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 42
• Issue: 5
• Pages: 505-510
• DOI: https://doi.org/10.1111/jvp.12775
• Keywords: Pharmacology; General Veterinary
• Public URL: https://nottingham-repository.worktribe.com/output/2097254
• Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1111/jvp.12775
• Additional Information: This is the peer reviewed version of the following article: Morris, T, Paine, SW, Zahra, P, Li, E, Colgan, S, Karamatic, S. Plasma and urine pharmacokinetics of intravenously administered flunixin in greyhound dogs. J vet Pharmacol Therap. 2019; 00: 1– 6. https://doi.org/10.1111/jvp.12775, which has been published in final form at https://doi.org/10.1111/jvp.12775. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
• Contract Date: May 28, 2019