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 The objective was to use histamine to induce a similar degree of nasal congestion as a natural common cold (from unpublished data of 250 cold sufferers) and thus establish a rapid screening system for decongestant drug effects. Sixtynine normal subjects were challenged with histamine diphosphate (300 micrograms/nostril) on 2 visits. Thirtytwo subjects were identified showing reproducible baseline values (< 15%CV (coefficient of variation)) and adequate nasal congestion (minimum 20%) without excessive sneezing. Reproducibility was evaluated in them post challenge using acoustic rhinometry and rhinomanometry. Twentythree subjects showed a variation < 25%CV of nasal volume over multiple visits in a 5 month period. The average reduction in nasal volume and airflow 15 minutes post challenge was 32% and 41% respectively. Acoustic rhinometry values were less variable than rhinomanometry values. Negligible differences (< 2%) in histamine response over visits and similar correlation between measured values at first, second and last visits indicate that 2 visits are adequate to evaluate response reproducibility in a selected population. We conclude that it is feasible to develop a robust clinical model of nasal congestion using histamine.