The efficacy of
ketotifen, a tricyclic benzocycloheptathiophene derivative, was assessed in an outpatient clinical trial and in a group of 12 asthmatic subjects with
exercise-induced asthma. Subjects in the outpatient trial had mild
asthma and consisted of two groups: a group of 24 atopic asthmatics with at least one positive skin test reaction and with an associated history of bronchial reactivity to at least one
allergen; and a group of eight asthmatics with one or more positive skin prick tests but not bronchial reactivity to an
allergen. Both groups took four weeks medication of
ketotifen 1 mg bd and placebo in a randomised double-blind crossover study. There was no difference between
ketotifen and placebo for any measurement made during the study and consequently no evidence of
drug efficacy. The exercise study followed a standardised protocol and each subject took in random double-blind order, placebo, 1 mg, 2 mg, and 4 mg
ketotifen two hours before exercise. There was no difference in the mean decreases in lung function from pre-exercise baseline values after three doses of
ketotifen than with placebo.
Drug levels suggested
ketotifen was well absorbed. It would appear that if given for a period of only four weeks
ketotifen had no beneficial effects in the management of mild
asthma, and that a single dose before exercise does not modify
exercise-induced asthma.