Distribution of Flunixin Meglumine and Firocoxib into Aqueous Humor of Horses
Version of Record online: 22 JUL 2011
Copyright © 2011 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 25, Issue 5, pages 1127–1133, September/October 2011
How to Cite
Hilton, H.G., Magdesian, K.G., Groth, A.D., Knych, H., Stanley, S.D. and Hollingsworth, S.R. (2011), Distribution of Flunixin Meglumine and Firocoxib into Aqueous Humor of Horses. Journal of Veterinary Internal Medicine, 25: 1127–1133. doi: 10.1111/j.1939-1676.2011.0763.x
- Issue online: 20 SEP 2011
- Version of Record online: 22 JUL 2011
- Submitted January 10, 2011; Revised April 27, 2011; Accepted May 24, 2011.
Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used systemically for the treatment of inflammatory ocular disease in horses. However, little information exists regarding the ocular penetration of this class of drugs in the horse.
Objective: To determine the distribution of orally administered flunixin meglumine and firocoxib into the aqueous humor of horses.
Animals: Fifteen healthy adult horses with no evidence of ophthalmic disease.
Methods: Horses were randomly assigned to a control group and 2 treatment groups of equal sizes (n = 5). Horses assigned to the treatment groups received an NSAID (flunixin meglumine, 1.1 mg/kg PO q24h or firocoxib, 0.1 mg/kg PO q24h for 7 days). Horses in the control group received no medications. Concentrations of flunixin meglumine and firocoxib in serum and aqueous humor and prostaglandin (PG) E2 in aqueous humor were determined on days 1, 3, and 5 and aqueous : serum ratios were calculated.
Results: Firocoxib penetrated the aqueous humor to a significantly greater extent than did flunixin meglumine at days 3 and 5. Aqueous : serum ratios were 3.59 ± 3.32 and 11.99 ± 4.62% for flunixin meglumine and firocoxib, respectively. Ocular PGE2 concentrations showed no differences at any time point among study groups.
Conclusions and Clinical Importance: Both flunixin meglumine and firocoxib penetrated into the aqueous humor of horses. This study suggests that orally administered firocoxib penetrates the aqueous humor better than orally administered flunixin meglumine at label dosages in the absence of ocular inflammation. Firocoxib should be considered for the treatment of inflammatory ophthalmic lesions in horses at risk for the development of adverse effects associated with nonselective NSAID administration.