Abstract
Abstract: :
Purpose: To determine if pre-operative topical administration of ciprofloxacin or ofloxacin results in aqueous humor drug concentrations that exceed the MIC90 of common ocular contaminants in dogs undergoing cataract surgery. Methods: Dogs undergoing elective bilateral phacoemulsification surgery were enrolled with owner consent. Twelve dogs (10 males, 2 females; ages 2 to 14 years; 10 breeds) and thirteen dogs (7 males, 6 females; ages 1 to 12 years; 8 breeds) participated in the ciprofloxacin and ofloxacin studies respectively. Dogs with corneal ulceration or evidence of active uveitis were excluded. The night before surgery, patients were topically treated once with 0.3% ciprofloxacin or 0.3% ofloxacin. Two hours before surgery, patients received 1 drop of 0.3% ciprofloxacin or ofloxacin every 15 minutes for 8 treatments total. Immediately before the incision, aqueous humor was collected and frozen at -70°C. Samples demonstrated a time course with first eye samples (S1) being a shorter time from treatment than second eye samples (S2). Samples were analyzed by HPLC at the NCSU Clinical Pharmacology laboratory; negative and positive controls using normal canine aqueous humor had 100% recovery and accuracy. Results: In ciprofloxacin patients, S1 were 0.03 µg/ml-0.69 µg/ml with 0.17 µg/ml median, and S2 were 0.09 µg/ml-0.95 µg/ml with 0.36 µg/ml median. S2 was significantly greater than S1. No eyes exceeded MIC90 for Streptococcus sp; few eyes (1/12 = 8%, CI 0-28% OU) exceeded MIC90 for Staphylococcus sp or Corynebacterium sp; moderate numbers (5/12 = 42%, CI 10-74% S1; 8/12 = 67%, CI 36-98% S2) exceeded MIC90 for E. coli. In ofloxacin patients, S1 were 0.48 µg/ml-2.81 µg/ml with 1.05 µg/ml median, and S2 were 0.45 µg/ml-3.63 µg/ml with 1.30 µg/ml median. A suggestion that S2 > S1 existed. Few eyes exceeded MIC90 for Streptococcus sp or Corynebacterium sp (2/13 = 15%, CI 0-39% S1; 1/13 = 8%, CI 0-26% S2); moderate numbers (7/13 = 54%, CI 23-85% S1; 9/13 = 69%, CI 40-98% S2) exceeded MIC90 for Staphylococcus sp; most eyes (12/13 = 92%, CI 74-100% OU) exceeded MIC90 for Bacillus sp; all eyes exceeded MIC90 for E. coli (13/13 = 100%, CI 96-100% OU). Ciprofloxacin and ofloxacin concentrations were not related to body-surface area. Conclusions: Ofloxacin has higher corneal penetration and ability to achieve MIC90 of common ocular contaminants than ciprofloxacin. In this pilot study, ciprofloxacin aqueous humor concentrations did not exceed MIC90 for most canine ocular contaminants but ofloxacin exceeded MIC90 for a moderate number of contaminants and would be a more appropriate prophylactic choice for canine cataract patients.
Keywords: antibiotics/antifungals/antiparasitics • pharmacology • endophthalmitis