An in vivo study comparing the ocular absorption of levofloxacin and ciprofloxacin prior to phacoemulsification

To compare aqueous humor concentrations of levofloxacin vs ciprofloxacin when used as prophylactic medications before phacoemulsification. Patients (n = 93) were randomly assigned to receive either 0.5% levofloxacin (Quixin) or 0.3% ciprofloxacin (Ciloxan) using one of the following dosing regimens: (A) 1 to 2 drops four times a day for 2 days preoperatively; (B) 5 doses (1 to 2 drops) delivered every 10 minutes in the hour immediately preceding surgery; or (C) the combination of A and B. Aqueous samples (0.1 ml) were obtained immediately before surgery, and drug concentrations were measured using high performance liquid chromatography/mass spectrometry. The mean concentration of levofloxacin in the aqueous humor was significantly greater than that of ciprofloxacin in all treatment groups (P < .001): 284.8 vs 67.4 μg/ml (regimen A); 1,135.6 vs 185.6 μg/ml (regimen B); and 1,618.6 vs 241.5 (regimen C). Dosing regimen B delivered significantly more drug to the aqueous humor than regimen A for both levofloxacin (P ≤ .001) and ciprofloxacin (P = .004). Dosing regimen C delivered significantly more drug to the aqueous humor than regimen B for levofloxacin (P = .05) but not for ciprofloxacin (P = .384). Although the concentration of active drug in levofloxacin is approximately 1.7-fold higher than that in ciprofloxacin, the aqueous concentration of levofloxacin after topical administration was four to seven times greater than ciprofloxacin; these differences were statistically significant. With dosing regimens B and C, levofloxacin concentrations in the aqueous humor were above the MIC90 for most common ocular pathogens, including Staphylococcus and Streptococcus species. Ciprofloxacin did not reach such concentrations in any treatment group.