Pharmacokinetics of topically applied ciprofloxacin in equine tears.
OBJECTIVE
To evaluate the pharmacokinetics of topically applied ciprofloxacin 0.3% ophthalmic solution in tears of healthy horses.


METHODS
Twenty healthy, adult, mixed-breed horses.


METHODS
Twenty study horses were confirmed free of ophthalmic disease by complete ophthalmic examination. Seventy microliters of 0.3% ciprofloxacin (Ciloxan) was placed in the ventral cul-de-sac of each eye using a microliter syringe and 19-g cannula. Population kinetics were carried out by sampling the tear film from the lower cul-de-sac of each eye with tear test strips at 5, 10, 15 and 30 min and 1, 2, 4 and 6 h post administration for a total of five samples at each time-point. Sample collection time was 15 s. Concentrations of ciprofloxacin were determined using high performance liquid chromatography.


RESULTS
Mean (+/-SD) of the Schirmer tear test results from all eyes was 23.4 +/- 4.8 mm wetting in 1 min. Mean concentration of ciprofloxacin in the tears at 5 min post administration was 498.4 +/- 266.8 microg/g. Mean concentration rapidly declined and began to plateau at 30 min. The mean tear concentrations of ciprofloxacin at 30 min and at 1, 2, 4 and 6 h were 66.6 +/- 56.0, 60.25 +/- 55.7, 42.25 +/- 30.9, 36.25 +/- 32.0, and 45.5 +/- 46.5 microg/g, respectively.


CONCLUSIONS
The pharmacokinetics of ciprofloxacin in normal horses are similar to those in rabbits and humans. Topical application of ciprofloxacin resulted in a mean tear concentration of ciprofloxacin that remained above the MIC(90) levels for most pathogenic bacteria for 6 h post administration.
Hendrix
Diane V H
DV
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996-4544, USA. dhendrix@utk.edu
Stuffle
Jamie L
JL
Cox
Sherry K
SK
D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D002939:Ciprofloxacin / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006736:Horses / Q000378:metabolism*; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D013666:Tears / Q000378:metabolism*
D000890:Anti-Infective Agents; D009883:Ophthalmic Solutions; D002939:Ciprofloxacin