Ciprofloxacin and ofloxacin aqueous humor concentrations after topical administration in dogs undergoing cataract surgery

OBJECTIVE: To determine if preoperative topical administration of ciprofloxacin or ofloxacin results in aqueous humor drug concentrations that exceed the MIC(90) of common ocular contaminants in dogs undergoing cataract surgery. PROCEDURES: Twelve dogs were treated with topical 0.3% ciprofloxacin and 13 dogs with topical 0.3% ofloxacin once the night before surgery, and then with 1 drop of ciprofloxacin or ofloxacin every 15 min for 2 h immediately before surgery. Aqueous humor samples were taken from each eye immediately before the incision was made and frozen at -70 degrees C. First eye samples (S1) were taken closer to the time of topical treatments than second eye samples (S2). Samples were analyzed by high performance liquid chromatography (HPLC) at the North Carolina State University (NCSU) Clinical Pharmacology laboratory. RESULTS: In ciprofloxacin patients, S1 concentrations were 0.03-0.69 (0.17 median) microg/mL, and S2 concentrations were 0.09-0.95 (0.36 median) microg/mL. Aqueous humor concentrations did not exceed the MIC90 of Streptococcus sp. Few eyes (1/12 OU) exceeded the MIC90 for Staphylococcus sp. or Corynebacterium sp.; moderate numbers (5/12 S1; 8/12 S2) exceeded the MIC90 for E. coli. In ofloxacin patients, S1 concentrations were 0.48-2.81 (1.05 median) microg/mL, and S2 concentrations were 0.45-3.63 (1.30 median) microg/mL. Although few eyes (