EFFECTS OF LORATADINE AND TERFENADINE ON THE INDUCED NASAL ALLERGIC REACTION

Objective: To evaluate the effect of terfenadine and loratadine on the early nasal allergic response to challenge and the subsequent cellula r influx and hyperresponsiveness. Design: Double-blind, placebo-contro lled, triple-crossover study. Subjects: Fourteen, asymptomatic, allerg ic volunteers. Interventions: After an initial challenge with methacho line chloride, subjects received treatment with placebo, loratadine (1 0 mg by mouth daily), or terfenadine (60 mg by mouth twice daily) for 1 week, followed by a nasal allergen challenge with lavages; 24 hours later, while the subjects were still receiving medication, the quantit y of cells in the nasal lavage was determined, and another challenge w ith methacholine was done. Mediator levels were quantified in nasal la vages after the allergen challenge, and the weight of the methacholine -induced nasal secretions was measured. Results: Both loratadine and t erfenadine treatment resulted in significant reductions in allergen-in duced sneezing and the levels of histamine, kinins, albumin, and N-alp ha-tosyl-L-arginine methyl ester-esterase activity in recovered nasal lavages compared with the reductions that resulted from placebo treatm ent, with no significant difference among the treatments. Treatment ha d no effect on the levels of tryptase,prostaglandin D-2, or leukotrien e C-4. A significant eosinophil influx into nasal secretions 24 hours after the allergen challenge in patients who were receiving placebo (P =.006) was not affected by loratadine or terfenadine treatment. Compar ing methacholine-induced secretions between screening challenges and c hallenges with the patients who were being treated with either loratad ine or terfenadine, there was a significant decrease in secretions aft er the use of these antihistamines (P<.05). Conclusion: Both loratadin e and terfenadine partially inhibit the early nasal response to allerg en challenge and the subsequent reactivity to a challenge with methach oline without affecting the influx of eosinophils into nasal secretion s.