Intranasal
flunisolide is an effective treatment for
allergic rhinitis.
Flunisolide has high bioavailability when administered to normal subjects (50% of an intranasal dose reaches the systemic circulation) with minimal systemic effects. Bioavailability in patients with active
rhinitis averages 62.4 +/- 15.7%. The oral dose bioequivalent to 100 micrograms intranasally is 500 micrograms. To define the comparative trial and systemic effects of intranasal
flunisolide in patients with active
allergic rhinitis, a multicenter, randomized, double-blind, placebo-controlled study was conducted during the 1983 ragweed
hayfever season. Ninety-nine patients with ragweed
hayfever for greater than or equal to 2 years and positive prick skin tests to ragweed were randomly allocated to one of three treatment groups: 0 = oral
flunisolide 500 micrograms b.i.d. and intranasal placebo b.i.d.; N = intranasal
flunisolide 50 micrograms per nostril b.i.d. and oral placebo b.i.d.; P = intranasal and oral placebo b.i.d. Treatment continued for 4 weeks. Patients kept daily symptom scores. Patients were evaluated by a blinded observer every 2 weeks and were globally evaluated at the study's end. Data were analyzed for each center and pooled. There were no significant differences in symptom severity of
sneezing, nasal congestion, and throat itch in the 0 (oral
flunisolide) and P (placebo) groups. N (nasal
flunisolide) was significantly more effective than O or P (P less than or equal to 0.005) for each symptom for at least one 2-week period. Global evaluation demonstrated control of overall
hayfever severity for N (nasal
flunisolide) but not for O (oral
flunisolide). We conclude that the therapeutic efficacy of
flunisolide is achieved by topical and not by systemic action.