Preventive effect of ketotifen, a new antiallergic agent, on histamine‐induced bronchoconstriction in asthmatics

Abstract

The preventive effect of ketotifen, a new drug with anti-histaminic and anti-allergic properties, on histamine-induced bronchoconstriction was studied by open assessment in 24 adult patients with extrinsic asthma. A single oral dose of 1 mg ketotifen reduced the post-histamine mean drop in peak expiratory flow from 33 to 16% of the basal values (P < 0.001). After a 4 wk regimen of 1 mg ketotifen twice daily the post-drug histamine-induced fall in PEF was further significantly reduced (P < 0.001). Tests performed after 8 and 12 wk of treatment showed no additional decrease in bronchial reactivity to histamine. Tests performed 1 wk after cessation of treatment showed return of bronchial reactivity to the pre-treatment level. A single dose of ketotifen may have a marked preventive effect on histamine-induced bronchoconstriction; this effect may be enhanced during continued treatment.