Nasal histamine challenge: a reproducible model of induced congestion measured by acoustic rhinometry

We describe the development of a clinical model of nasal congestion using a fixed dose histamine challenge in normals. The objective was to use histam ine to induce a similar degree of nasal congestion as a natural common cold (from unpublished data of 250 cold sufferers) and thus establish a rapid s creening system for decongestant drug effects. Sixtynine normal subjects we re challenged with histamine diphosphate (300 mug/nostril) on 2 visits. Thi rtytwo subjects were identified showing reproducible baseline values (< 15% CV(coefficient of variation)) and adequate nasal congestion (minimum 20%) w ithout excessive sneezing. Reproducibility was evaluated in them post chall enge using acoustic rhinometry and rhinomanometry. Twentythree subjects sho wed a variation <25%CV of nasal volume over multiple visits in a 5 month pe riod. The average reduction in nasal volume and airflow 15 minutes post cha llenge was 32% and 41% respectively. Acoustic rhinometry values were less v ariable than rhinomanometry values. Negligible differences (< 2%) in histam ine response over visits and similar correlation between measured values at first, second and last visits indicate that 2 visits are adequate to evalu ate response reproducibility in a selected population. We conclude that it is feasible to develop a robust clinical model of nasal congestion using hi stamine.