Corneal pharmacokinetic of topically applied azithromycin and clarithromycin

Purpoe To determine corneal level of topically adminitered azithromycin and clarithromycin in a rabbit model. Deign Experimental animal tudy. Method Cornea of New Zealand albino rabbit were treated with topical azithromycin (2 mg/ml or 4 mg/ml) or clarithromycin (10 mg/ml). Topical azithromycin wa prepared from an intravenou olution and topical clarithromycin from a upenion for oral ue. All rabbit received one drop every 2 hour on the right eye. Group of rabbit were treated for the following interval: 6, 12, 24, and 48 hour (four rabbit for each combination of time point, drug, and doe). Corneal tiue wa removed 1 hour after the lat application. To invetigate tability of tiue azithromycin level, an additional group of four rabbit wa treated for 24 hour, but corneal tiue wa not removed until 24 hour later. ample were homogenized, and drug concentration were meaured uing high-preure liquid chromatography (HPLC) analyi and bioactivity aay. Reult Corneal concentration of azithromycin increaed with drug doage and duration of application. Rabbit treated with azithromycin tolerated the drug well without ign of irritation. Clarithromycin wa undetectable in corneal tiue by HPLC and bioactivity aay for all rabbit. ome rabbit treated with clarithromycin had ign of ocular urface irritation. Concluion Meaurable concentration of azithromycin are achieved in corneal tiue after topical application in a rabbit model, and the drug i well tolerated. Azithromycin may be a ueful antibiotic for the topical treatment of human corneal infection, but clarithromycin, in currently available formulation, may not be effective becaue of poor tiue penetration.