Duration of protection by oxitropium bromide against cholinergic challenge.

In order to determine the duration of action of the inhaled anticholinergic agent oxitropium bromide, a controlled study of the effect of pre-treatment with oxitropium bromide 200 micrograms against cholinergic challenge was carried out in ten asthmatic subjects (6 children, 4 adults). After baseline measurements of lung function (FEV1 and sGaw) and methacholine PC20 (the concentration of methacholine to produce a 20% fall in FEV1) oxitropium bromide or placebo were inhaled double-blind on 2 separate days. Lung function and methacholine PC20 were then measured at 1, 3 and 6 h post dosing. Oxitropium bromide caused significant protection from methacholine challenge for 6 h (p less than 0.05).