Pharmacokinetic analysis of topical tobramycin in equine tears by automated immunoassay.
BACKGROUND
Ophthalmic antibiotic therapy in large animals is often used empirically because of the lack of pharmacokinetics studies. The purpose of the study was to determine the pharmacokinetics of topical tobramycin 0.3% ophthalmic solution in the tears of normal horses using an automated immunoassay analysis.


RESULTS
The mean tobramycin concentrations in the tears at 5, 10, 15, 30 minutes and 1, 2, 4, 6 hours after administration were 759 (±414), 489 (±237), 346 (±227), 147 (±264), 27.6 (±28.4), 14.8 (±66.6), 6.7 (±18.6), and 23.4 (±73.4) mg/L. Mean tobramycin concentration was maintained above the MIC90 for commonly isolated bacteria for 68.5 min.


CONCLUSIONS
A single dose of topical tobramycin resulted in therapeutic concentrations of tobramycin in the tears for 1 h after administration. Therapeutic levels of tobramycin remained in equine tears 6 times longer than was reported in rabbit tears.
Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada.
Sarah L
SL
Czerwinski
Andrew W
AW
Lyon
Brian
B
Skorobohach
Renaud
R
Léguillette
D000287:Administration, Topical; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D001331:Automation; D005260:Female; D006736:Horses; D007118:Immunoassay / Q000379:methods / Q000662:veterinary*; D008297:Male; D015203:Reproducibility of Results; D013666:Tears / Q000737:chemistry*; D014031:Tobramycin / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*
D000900:Anti-Bacterial Agents; D014031:Tobramycin