J Korean Ophthalmol Soc.  1987 Feb;28(1):23-29.

Corneal Tobramycin Levels by Topical Administration of Fortified Tobramycin Solutions in Rabbits

• Chung I
• Kim HB
• Kim EK
• Lee CK

Abstract

Bacterial keratitis is a common ophthalmic disease. In certain cases of pseudomonas keratitis, the corneal perforation may occur within 24-48 hours of the onset. Soa suitable, massive antibiotic should be promptly used in these cases. Intensive topical therapy with fortified aminoglycoside antibiotics is a current mainstay in the treatment of bacterial keratitis because insufficient antibiotic concentrations may not inhibit bacterial growth. In 1985, Glasser and associates reported the effect of longer dosing intervals on corneal gentamicin levels with using topical fortified gentamicin solutions in rabbits. We compared peak and trough antibiotic levels achieved in the rabbit cornea by various topical administrations of tobramycin which was prepared in a concentration of 13.6mg/ml by fortifying commercially available ophthalmic tobramycin solution with injectable drug. A loading dose consists of one drop given every minute for five minutes. 1. Eyes receiving one drop every hour(Group 1) and three drops every two hours(Group 5) showed little conjunctival hyperemia. Eyes given one drop every 30 minutes(Group 2) developed minimal inflammatory responses, as did eyes given a single loading dose followed by one drop each hour(Group 4). The moderate inflammatory response occurred in eyes receiving sequential loading doses(Group 3). Abnormalities in the cornea and the iris were not seen in all studied groups. 2. Gentamicin peak level in sequential loading doses group(Group 3) was significantly higher than those achieved by one drop every hour(Group 1) or one drop every 30 minutes(Group 2). At two hours of gentamicin administration, sequential loading doses(Group 3) produced remarkably high concentrations: than those produced in Group 1, Group 2, or three drops every two hours(Group 5). During the first four hours, Group 3 represented high antibiotic levels than those produced in Group 1, Group 2, Group 5, or a single loading dose followed by one drop each hour(Group 4). There were no significant differences between trough levels with on drop every hour(Group 1) and three drops every two hours(Group 5).

MeSH Terms

Administration, Topical*
Anti-Bacterial Agents
Cornea
Corneal Perforation
Gentamicins
Hyperemia
Iris
Keratitis
Pseudomonas
Rabbits*
Tobramycin*
Anti-Bacterial Agents
Gentamicins
Tobramycin