BACTERIAL KERATITIS THERAPY IN GUINEA-PIGS WITH LOMEFLOXACIN BY INITIALLY HIGH-DOSAGE FOLLOWED BY LOW-DOSAGE REGIMEN

Lomefloxacin is known to have an excellent corneal penetration. The th erapeutic effect of two specific treatment regimens with lomefloxacin 0.3% eye drops was studied in a Pseudomonas aeruginosa-induced keratit is model in guinea pigs. An initial loading dose of 1 drop every 5 min for 5 times was used in all groups. Its purpose was to obtain high ba ctericidal corneal levels in the two actively treated groups, The foll ow-up treatment for 7 days was by a twice daily regimen in one group a nd 3 times daily in the other treated group. There were two control gr oups - one with no treatment and the other with vehicle treatment (ini tial loading dose followed by twice daily regimen), Clinical signs of cornea, conjunctiva and eye adnexae improved significantly within 2 da ys in both lomefloxacin regimens, whereas clinical signs deteriorated with vehicle treatment. Fifty percent of the animals treated with lome floxacin showed no colonies in the swab culture after 2 days of therap y, while all vehicle-treated animals were positive even at day 6, with 5 out of 9 animals continuing to be positive at day 8. Pseudomonas in the range of 100-2,300 colonies was isolated from the grounded and cu ltured cornea at the end of the study in 4 out of 9 vehicle-treated an imals but in none of the lomefloxacin-treated guinea pigs. The biggest difference in the degree of secondary inflammation between lomefloxac in and vehicle-treated groups was observed in the cornea which was the target tissue of infection. An unexpected observation was the lower d egree of corneal inflammation in the twice daily treated animals when compared to the 3 times daily treatment group. This finding may be due to the somewhat lower initial degree of corneal inflammation in this group and suggests that the course of corneal recovery is predominatel y dependent on the initial degree of infection with both dosage regime ns of lomefloxacin capable of eradicating corneal organisms.