Tear, cornea, and aqueous humor concentrations of ciprofloxacin and moxifloxacin after topical ocular application in ophthalmologically normal horses.

This study investigates the concentration levels of the drugs ciprofloxacin and moxifloxacin in ocular tissues and fluids of horses after being applied topically. The results indicate that these drugs can reach therapeutic concentrations in horse tears and corneal tissue, even when the epithelium is intact.

Methodology

• The researchers used 24 adult horses with no known ocular conditions as subjects for this study.
• Each horse had a 0.1 mL solution of either 0.3% ciprofloxacin or 0.5% moxifloxacin applied to the ventral conjunctival fornix (the space between the eye’s lower lid and the eyeball) in one eye. The timing of the applications varied between the test groups.
• Post-application, the team collected tears, corneal tissue, and aqueous humor (the transparent fluid in the front of the eyeball) at different time intervals, depending on the group.
• The researchers determined drug concentrations through high-performance liquid chromatography, an analytical chemistry technique used to identify, quantify, and separate each component in a mixture.

Results

• The concentration of ciprofloxacin in tears, corneal tissue, and aqueous humor varied across the groups, with the highest median concentration observed in group 1 for tears and corneal tissue. However, the concentrations in aqueous humor were lower than the quantification limit for all groups.
• Moxifloxacin concentrations were also measured. In tears, the highest median concentration was observed in group 1. Regarding the corneal tissue, the highest concentration was found in group 1, while in aqueous humor, all groups showed low concentrations.
• The team noted a significant difference between the corneal moxifloxacin concentrations in group 1 and groups 2 and 3.

Conclusions

• This study proves that when ciprofloxacin and moxifloxacin are topically applied to the eye, they can reach therapeutic levels in the tears and corneal tissue of horses, regardless of the state of the epithelium.
• This information can be beneficial for future medical treatments and therapeutic measures in veterinary medicine, especially regarding ocular conditions in horses.