Ocular Distribution of Lomefloxacin 0.3% After a Single Instillation in the Infected Eye of Pigmented Rabbits

Abstract

ABSTRACT

We investigated the distribution of lomefloxacin, a fluoroquinolone, in the infected eye of pigmented rabbits after one instillation of 50 μl lomefloxacin 0.3 % eye drop, and compared tissue concentrations with therapeutic levels.

Infection was induced by 6 instillations of Pseudomonas aeruginosa inoculum (6 × 10⁵ bacteria) on centrally scratched cornea of 32 pigmented rabbits. Fifty microliters of ¹⁴[C] lomefloxacin 0.3 % were instilled 24 hours after infection and animals were sacrificed 0.25, 0.5, 1, 2, 4, 8 and 12 hours later. Ocular structures, tear fluid, whole blood and plasma were then sampled, and tissue levels over time, Tmax, Cmax and area under the curve (AUC) were calculated.

Lomefloxacin rapidly penetrated into the ocular structures: tear (Tmax 0.25 hours, Cmax 366 μg/ml, AUC 360 μg/ml × hour), corresponding values were for: eye lids (0.25, 7, 33), conjunctiva (0.25, 11, 7), cornea (0.25, 56, 70), aqueous humor (1, 8, 14), iris ciliary-body (4, 34, 252), lens (1, 0.2, 0.6). Tear levels remained high for many hours and were 34, 48, 1 and 27 μg/ml at 1, 2, 4 and 8 hours following a single instillation. Elimination from ocular structures was rapid.

Therapeutic levels were achieved after a single instillation (mainly in the external ocular structures) when compared with MIC 90 % values (1-10 μg/ml).