Protective effect of loratadine on specific conjunctival provocation test

The protective effect of loratadine (anti-H1 antagonist) on clinical and cellular processes following the early phase of specific conjunctival provocation test was assessed in 20 patients affected by seasonal allergic rhinoconjunctivitis, in a double-blind, randomized, placebo-controlled, parallel-group study. Patients were randomly assigned to two treatment groups, each being given a single daily dose of loratadine 10 mg or placebo, for 7 days, out of pollen season. Pretreatment with Loratadine resulted in a significant higher allergen threshold dose than placebo (p less than 0.01). Patients treated with loratadine experienced a significant reduction (p less than 0.01) in conjunctival symptom severity as compared with placebo, following conjunctival challenge. Finally, the number of inflammatory cells was lower in the loratadine-treated patients compared to the placebo group (p less than 0.01). In conclusion, loratadine exerts a significant protective effect on the early phase cellular and clinical events of conjunctival reaction induced by allergen challenge in atopic patients.