Objective: To measure the rabbit ocular tissue concentration of lomefloxacin (LMLX) after its topical application.
Methods: Fifteen rabbits (30 eyes) for the experiment (12 white rabbits and 3 pigmented rabbits) were divided into 5 groups. In the 1st group, 0.3% LMLX eyedrops were instilled once (1 drop each) in the 3 white rabbit's eyes. In the 2nd group, 0.3% LMLX eyedrops were instilled for 6 times (1 drop once) with an interval of 5 minutes in the 3 white rabbit's eyes. In the 3rd group, 0.3% LMLX eyedrops were instilled once (1drop each) in the 3 white rabbit's eyes after removal of corneal epithelium. In the 4th group, 0.3% LMLX eyedrops were instilled once (1 drop each) in the 3 pigmented rabbit's eyes. In the 5th group, LMLX 0.5 mg was subconjunctivally injected in the 3 white rabbit's eyes. After the administration for 30 minutes, aqueous humor was collected and the eyeball was enucleated. All measurements were performed by high-pressure liquid chromatography (HPLC).
Results: In the 1st group, the mean levels of drug were 8.75 +/- 3.09 microg/g in cornea, 0.21 +/- 0.1 microg/ml in aqueous humor, and 1.49 +/- 0.39 microg/g in iris, respectively. The ocular tissue concentrations of the other groups were significantly higher than that of the 1st group. The pigmented tissue of pigmented rabbit's eyes had relatively high concentration of LMLX.
Conclusion: All concentrations of LMLX in rabbit's eyes are above the minimum inhibitory concentration for 90% (MIC(90)) of most bacterial pathogens. LMLX has greater affinity in the pigmented tissue. These results show that LMLX may be an effective antimicrobial agent for prophylactic use in ophthalmic surgery and also for the treatment of intraocular infections due to susceptible organisms.