Pharmacologic intervention in the management of allergic conjunctivitis was evaluated with different topical ocular agents in man. Their effect can be precisely assessed with the conjunctival provocation test (CPT). A potent specific H1-receptor antagonist, 0.05% mequitazine eye-drops, was tested in a double-blind randomized, placebo-controlled study using CPT with grass pollen allergens. Twenty healthy subjects allergic to grass pollen were included outside the pollen season after a positive CPT screening. They received one drop of 0.05% mequitazine in one eye and the vehicle in the contralateral eye in a random order, four times daily for 5 days. CPT was performed 15 min after the last instillation, and the threshold dose inducing a positive reaction was determined. Results were given by Abelson's composite score including redness, chemosis, tearing, and itching. Topical 0.05% mequitazine significantly reduced the composite score compared to placebo. The allergen threshold concentration which induced the positive conjunctival reaction was higher in mequitazine pretreated eyes. No side-effect was reported. These data clearly suggest that mequitazine has potential to treat allergic conjunctivitis.

These results demonstrate the superior efficacy of a single drop of 0.05% mequitazine 15 min before CPT compared with 2% disodium cromoglycate 4 times daily for 4 days.

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