Aqueous humor and plasma concentrations of a compounded 0.2% solution of terbinafine following topical ocular administration to normal equine eyes.

OBJECTIVE: To determine the transcorneal penetration and systemic absorption of a compounded 0.2% terbinafine solution following repeated topical administration to normal equine eyes. Sample population Six healthy adult horses with normal ocular examinations. PROCEDURES: One eye of each horse received 0.2 mL of a compounded 0.2% terbinafine solution every 4 h for seven doses. During the 1 h following administration of the final dose, multiple peripheral blood samples were obtained, and a single aqueous humor (AH) sample was collected at the end of the hour. AH and plasma concentrations of terbinafine were determined using high pressure liquid chromatography (HPLC). Stability of the formulation was assessed with HPLC analysis over a 14-day time period. RESULTS: Terbinafine was not detected in the AH or plasma of any horse at any time point. No signs of ocular irritation or systemic toxicity were noted in any horse at any time point. The solution was stable over 14 days. CONCLUSION: Topical ocular administration of compounded 0.2% terbinafine solution does not result in detectable AH or plasma levels following administration to normal equine eyes, suggesting its use for deep corneal or intraocular fungal infections in equine ophthalmology may be limited.

Aqueous humor and plasma concentrations of ciprofloxacin and moxifloxacin following topical ocular administration in ophthalmologically normal horses.

OBJECTIVE: To determine the degree of ocular penetration and systemic absorption of commercially available topical ophthalmic solutions of 0.3% ciprofloxacin and 0.5% moxifloxacin following repeated topical ocular administration in ophthalmologically normal horses. ANIMALS: 7 healthy adult horses with clinically normal eyes as evaluated prior to each treatment. PROCEDURES: 6 horses were used for assessment of each antimicrobial, and 1 eye of each horse was treated with topically administered 0.3% ciprofloxacin or 0.5% moxifloxacin (n = 6 eyes/drug) every 4 hours for 7 doses. Anterior chamber paracentesis was performed 1 hour after the final dose was administered, and blood samples were collected at 24 (immediately after the final dose), 24.25, 24.5, and 25 hours (time of aqueous humor [AH] collection). Plasma and AH concentrations of ciprofloxacin or moxifloxacin were determined by use of high-performance liquid chromatography. RESULTS: Mean +/- SD AH concentrations of ciprofloxacin and moxifloxacin were 0.009 +/- 0.008 microg/mL and 0.071 +/- 0.029 microg/mL, respectively. The AH moxifloxacin concentrations were significantly greater than those of ciprofloxacin. Mean +/- SD plasma concentrations of ciprofloxacin were less than the lower limit of quantification. Moxifloxacin was detected in the plasma of all horses at all sample collection times, with a peak value of 0.015 microg/mL at 24 and 24.25 hours, decreasing to < 0.004 microg/mL at 25 hours. CONCLUSIONS AND CLINICAL RELEVANCE: Moxifloxacin was better able to penetrate healthy equine corneas and reach measurable AH concentrations than was ciprofloxacin, suggesting moxifloxacin might be of greater value in the treatment of deep corneal or intraocular bacterial infections caused by susceptible organisms. Topical administration of moxifloxacin also resulted in detectable plasma concentrations.