Corticosteroid-Antibiotic Interactions in Bacteria that Cause Corneal Infection

Although a comprehensive knowledge of antibiotic/corticosteroid combinations is essential for the appropriate treatment of eye infections, the impact of their co-administration has not been well studied to date. A systematic pharmacodynamic/pharmacokinetic study to determine the effects of cotreatment with various antibiotics and corticosteroids was conducted.

Four bacterial strains, seven antibiotics, and four corticosteroids were used in the analyses. Drug interactions were evaluated by considering antibacterial effects with a checkerboard assay and intracellular concentrations in human corneal epithelial cells.

The drug combinations that showed the most stable effects against Pseudomonas aeruginosa was levofloxacin-prednisolone. Stable combinations against the three types of Gram-positive bacteria were neomycin-prednisolone, ofloxacin-dexamethasone, ofloxacin-prednisolone, and polymyxin-dexamethasone. The cellular concentrations were changed for the gatifloxacin-fluorometholone, moxifloxacin-fluorometholone, tobramycin-dexamethasone, and tobramycin-prednisolone combinations.

Loteprednol and fluorometholone reduced the antibacterial effects of all of the tested antibiotics in this study. Dexamethasone and prednisolone showed various effects in this regard, depending on the co-administered antibiotic. Prior knowledge of specific antibiotic/corticosteroid interactions provides valuable information to clinical practitioners by combining data on the antibacterial and intracellular uptake effects of their co-administration.

When using antibiotics and corticosteroids, drug combinations can be selected by referring to the results of this study.