Ketotifen and methacholine-induced bronchospasm.

In a double-blind investigation the aspecific bronchus threshold was estimated by administration of methacholine to 16 young atopic patients with proven airways hyperreactivity (PC20 histamine less than or equal to 2 mg/ml. The influence of prolonged oral administration (12 weeks) of ketotifen (2 mg/day) on the bronchus threshold value has been studied. No significant elevation was found. It could be concluded that administration of ketotifen, even in prolonged administration, has no anticholinergic effects.