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Topical treatment of allergic conjunctivitis was initially based on vasoconstrictors; then sodium cromoglycate, ketorolac, and lodoxamide were added to the therapeutic armamentarium. Most recently, levocabastine, a long-acting topical antihistamine, and nedocromil, whose anti-inflammatory effect is thought to be mediated through chloride channel inhibition, have been added as agents for consideration as first-line therapy in allergic rhinitis and conjunctivitis. This trial compared the efficacy of the latter two agents in 25 men and women with a history of allergic conjunctivitis secondary to grass pollen sensitivity.
After determining the reaction threshold (i.e., the allergen dose required to produce itching and erythema covering at least 50% of the conjunctiva), subjects were randomized to receive one drop (the usual starting dose) of either topical levocabastine or nedocromil. Fifteen minutes later, progressive doses of allergen were administered until the patient again reached reaction threshold.
Both medications were significantly effective in reducing responses to pollen allergen. There were significantly more nonresponders to nedocromil than levocabastine (29% vs 4%). A marked reduction of allergen sensitivity was seen at least twice more frequently in recipients of levocabastine as compared to nedocromil. Severity of pruritus and erythema were significantly lower after levocabastine than nedocromil. Mild-to-moderate ocular irritation, the most frequent side effect, occurred in about one-third of recipients of both medications. The authors conclude that levocabastine is more effective than nedocromil in increasing conjunctival tolerance to allergen, inhibiting pruritus, and reducing erythema.
Hammann C, et al. J Allergy Clin Immunol 1996;98:1045-1050.