A COMPARISON OF THE EFFECTS OF AN ALPHA-AGONIST, AN ANTIMUSCARINIC AGENT AND PLACEBO ON INTRANASAL HISTAMINE CHALLENGE IN ALLERGIC RHINITIS

Autonomic receptors play a part in the physiology and pathology of the nasal mucosa. The effect of an alpha-agonist and an anti-muscarinic a gent on histamine-challenge was examined on patients with perennial al lergic rhinitis. Nine patients received saline, oxitropium bromide 0.0 75%, or xylometazoline hydrochloride 0.1% in a double-blind fashion. S equential challenge with increasing doses of histamine were given and resistance changes, sneezes and volume and content of secretion measur ed. Histamine challenge produced dose-related increases in nasal resis tance (P < 0.0001), lavage fluid volume (P < 0.01) and total protein ( P < 0.01). Following xylometazoline, histamine produced little increas e in resistance compared with saline and oxitropium bromide (P < 0.000 1). The latter reduced the dose-related increase in resistance (P < 0. 01) and nasal lavage fluid volume (P = 0.0007) and total protein (P = 0.023) seen with saline. These results confirm the importance of alpha -adrenergic and muscarinic receptors in the human nasal mucosa and sug gest mechanisms of action for these drugs in perennial allergic rhinit is.