The effect of ipratropium nasal spray on bronchial methacholine challenge

To determine the effect ipratropium bromide nasal spray has on methacholine challenge testing for airway hyperresponsiveness.

Ten subjects with known airway hyperresponsiveness to methacholine who had been clinically stable in the preceding 2 months participated in a randomized, double-blind, placebo-controlled, crossover study. Methacholine challenge testing was conducted on successive days: day 1 after pretreatment with aqueous 0.03% nasal ipratropium, and day 2 with normal saline solution placebo.

The provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) was higher after nasal ipratropium than after saline solution placebo (2.1 mg/mL vs 1.6 mg/mL, p = 0.02). This difference is equal to approximately one-half concentration difference, probably within the limits of reproducibility of the test.

Pretreatment with nasal ipratropium results in a small increase in PC20. Although this difference achieves statistical significance, it is probably not clinically significant.