Effect of ketorolac on Pseudomonas aeruginosa ocular infection in rabbits

Corticosteroids can exacerbate bacterial ocular infections, even in the presence of antibiotics. Ketorolac tromethamine is a new non-steroidal compound being considered as an anti-inflammatory ophthalmic drug. In this study, rabbits ocularly infected with Pseudomonas aeruginosa were treated topically with 0.4 percent tobramycin sulfate 4 times daily for 7 days to control infection. At the same times, either 0.5 percent ketorolac, 0.1 percent dexamethasone or vehicle was also given topically. Animals were scored for severity of both conjunctivitis (maximum severity rates score of 10) and corneal opacity (maximum of 4) using the Draize scale. Severity of the infection was determined by counting the number of punctate lesions which developed on the cornea. Nine days after treatment ended, the number of these lesions was the same for ketorolac as for the vehicle (respectively, 16.7 +/- 3 and 13.8 +/- 3, mean +/- SE, n = 24), indicating no exacerbation of the infection, whereas with dexamethasone these parameters increased (30.2 +/- 4, n = 24). During treatment, ketorolac reduced conjunctivitis (1.8 +/- 0.2, n = 120) when compared with the vehicle (2.9 +/- 0.2, n = 120), whereas dexamethasone did not (3.8 +/- 0.2, n V 120); neither ketorolac nor dexamethasone reduced corneal opacity (respectively, 2.3 +/- 0.05 and 2.6 +/- 0.1, n = 24) compared with vehicle (2.2 +/- 0.05, n = 24). After treatment, both conjunctivitis and corneal opacity became more severe only in dexamethasone treated eyes (respectively, 4.4 +/- 0.2, n = 120 and 3.0 +/- 0.02, n = 24). Thus, ketorolac appears to be an anti-inflammatory agent that does not worsen bacterial ocular infection.