Abstract
Purpose: The pharmacokinetics of a 2% ocular solution of azithromycin in DuraSite was evaluated in rabbits to determine whether the PK/PD parameters support a once-a-day for three-day therapeutic regimen against bacterial conjunctivitis. Materials and Methods: Mean levels of azithromycin were determined in tears, bulbar conjunctiva, cornea, and plasma following a single drop of 2% azithromycin. The levels were determined by HPLC-MS. Results: Concentrations of azithromycin peaked at 30 minutes. At the end of 24 hours, ocular tissue concentrations exceeded the MIC breakpoint for the most common causative pathogens of bacterial conjunctivitis by at least 7-fold. Conclusion: The PK/PD profile of 2% azithromycin suggests efficacy against common causative bacteria with just one dose per day for three days.