Aqueous Humor Bioavailability Comparison of Ciprofloxacin 0.3%, Levofloxacin 1.5%. Gatifloxacin 0.3% and Moxifloxacin 0.5% Following a Single Topical Drop Delivery

Abstract

Purpose: : To evaluate quantitatively over time the bioavailability of Ciprofloxacin 0.3%, Levofloxacin 1.5%. Gatifloxacin 0.3% and Moxifloxacin 0.5% in aqueous humor after topical administration

Methods: : A total of 64 New Zealand rabbit eyes were topically treated with a comercial available formulation of Ciprofloxacin 0.3%, Levofloxacin 1.5%, Gatifloxacin 0.3% and Moxifloxacin 0.5% eyedrops. Following an intial loading dose consistent of a single antibiotic drop the aqueous humor were sampled at 30 minutes, 1, 2 and 4 hours post-treatment. Biological activity was indirectly determined from the size of the zone of inhibition (ZOI) of filter paper disc soaked in 25µl of aqueous humor withdrawn from treated eyes and placed on an agar plate surface cultured with Staphylococcus Epidermidis.

Results: : Although not significant, 0.5% moxifloxacin eyedrops showed an initial (30 minutes and 1 hour post-treatment) trend towards superior aqueous bioactivity compared to all other tested formulations. At and following the second hour, the aqueous humor withdarwn from all treated eyes falied to demonstrte any bacteria inhibitory potential for the four tested formulations, since no zone of inhibition could be observed.

Conclusions: : Sole reliance on the minimum inhibitory concentration as guide to antibacterial efficacy may be misleading and even newer-generation fluoquinolones failed to demonstrate a significant aqueous bioavailability using a dosing regimen that simulated prophylactic use after cataract surgery.

Keywords: antibiotics/antifungals/antiparasitics • drug toxicity/drug effects • Staphylococcus