THE EFFECT OF TOPICAL FLUTICASONE PROPIONATE ON INTRANASAL HISTAMINE CHALLENGE IN SUBJECTS WITH PERENNIAL ALLERGIC RHINITIS

The mechanism of action of topical intranasal steroids is obscure. To investigate this, we have studied the effects of a topical intranasal corticosteroid, fluticasone propionate on nasal airflow resistance (Rn aw), secretions, cytological smears and symptoms. Fluticasone propiona te aqueous nasal spray was given to 11 patients with perennial allergi c rhinitis in a double-blind, placebo-controlled study. On each day, p atients were challenged with ascending doses of histamine. Rnaw, secre tion volume, total protein, mucin, lysozyme and albumin were measured. Nasal smears were taken and sneezes counted. Diary card data were col lected for both treatment periods. There was a significant, dose-relat ed increase in Rnaw and sneezing on histamine challenge. A single dose of fluticasone had no effect on any parameter. After 4 weeks of treat ment, resistance measurements were reduced (post-challenge g.m.2.8 cmH (2)O/l/s, Q1-Q3 1.6-4.8; placebo 4.2, 2.9-5.3: P < 0.0001) as were bas eline secretion volumes (mean 2.4 ml/5 min, c.i. 4.0-15.7; placebo 3.3 , 2.8-3.8: P < 0.05). Eosinophil counts were suppressed (fluticasone 5 .8%, c.i. 4.0-15.7; placebo 23.3%, 12.4-34.1: P < 0.05) and the compos ite symptom score reduced (P < 0.05). Fluticasone has long-term effect s on the nasal response to histamine in perennial allergic rhinitis an d part of this effect is likely to be vascular.