Application of histamine-induced conjunctivitis to the assessment of a topical antihistamine, levocabastine.

In an animal model, topical application of levocabastine to the eye inhibits the inflammatory conjunctival response to topically applied histamine. This is so even at one-fourth the concentration at which levocabastine is normally dispensed. Total blocking of histamine response continues for 24 h and is then irregularly observable for an additional 72 h. Levocabastine may be absorbed through the conjunctiva to give systemically transmitted protection to the contralateral eye. Levocabastine is a potent competitor against histamine for conjunctival H1 receptors and should prove a useful, possibly long-acting drug for the reversal of inflammatory conjunctivitis and inhibition of its recurrence.