Effectiveness of ciprofloxacin-polystyrene sulfonate (PSS), ciprofloxacinand ofloxacin in a Staphylococcus keratitis model.

PURPOSE. Staphylococcus aureus causessevere corneal infections that often result in corneal scarring and blindness.Presently, therapy often involves the use of a fluoroquinolone antibiotic.This study, employing an experimental rabbit model of Staphylococcus keratitis, compared the effectiveness of two commonly prescribed formulationsof fluoroquinolones to an experimental formulation, ciprofloxacin with polystyrenesulfonate (ciprofloxacin-PSS). The ciprofloxacin-PSS formulation uses an ionexchange resin to aid in the delivery of drug to the cornea. METHODS. Early (4–9 h postinfection, PI) and late (10–15 hPI) therapies were studied, employing 5 groups: ciprofloxacin-PSS, ciprofloxacin,ofloxacin, PSS vehicle, and untreated. Dosing regimens were: every 30 min,60 min, or a single drop applied at 9 h PI. Eyes were observed by slit lampexamination (SLE) and bacterial colony forming units (CFU) per cornea weredetermined. RESULTS. Early phase therapy with ciprofloxacin-PSS, ciprofloxacin, orofloxacin administered every 30 or 60 min were equally effective (P ≥ 0.2880),decreasing CFU per cornea by >5 log. Ciprofloxacin was significantly moreactive than ciprofloxacin-PSS or ofloxacin (P ≤ 0.0410) when applied asa single drop. Late therapy with ciprofloxacin-PSS, ciprofloxacin, or ofloxacinadministered every 30 or 60 min resulted in >3 log decrease in CFU per cornearelative to controls (P ≤ 0.0001). CONCLUSIONS. Topical treatment of experimental Staphylococcus keratitis with ciprofloxacin-PSS, ciprofloxacin, or ofloxacin was effective.The effectiveness of ciprofloxacin-PSS suggests that improved drug deliverysystems employing an ion exchange resin could be useful in an ocular fluoroquinoloneformulation. [ABSTRACT FROM AUTHOR]