A double-blind evaluation of topical levocabastine, a new specific H1 antagonist in patients with allergic conjunctivitis.

Forty patients suffering from allergic conjunctivitis, due to birch pollen, participated in a double-blind parallel group comparison between levocabastine (a potent new specific histamine (H1) antagonist) and placebo, both given as eye drops. Symptom scores were recorded during a 4-week period. A 1-week run-in period was followed by a 3-week treatment period. To enable a fair evaluation of the treatment effect on the ocular symptoms only, all patients were treated with topical nasal glucocorticoids for possible rhinitis symptoms during the whole study period. Plasma levels of levocabastine were determined in all subjects at the end of the 3 weeks' treatment period. Pollen counts for birch pollen were followed simultaneously. The evaluation of the symptom score cards revealed a significant reduction of ocular symptoms following use of the active compound. The resorption of the active substance through the conjunctiva was low. In accordance with the present trend of more topical treatment for allergic rhinitis, levocabastine may constitute a valuable compound for the topical treatment of allergic conjunctivitis.