[Protection from exertion-induced bronchial asthma with disodium cromoglycate (DSCG) (cromolyn, lomudal, intal) and with ketotifen (zaditen). Doubly crossed double-blind study ].

16 cooperative asthmatic patients with exercise-induced asthma (with more than 15% decrease in FEV1 after strenuous work on a treadmill with 10% upward; pulse rates over 180 per minute during the work-phase) were selected to take part in a double-blind crossover trial. The 8 women and 8 men, with ages ranging from 15 to 57 years (mean 25) underwent 4 exercise tests. The effects on exercise-induced asthma of 20 mg disodium cromoglycate (DSCG) inhaled with a spinhaler 30 minutes before exercise were compared to 2 mg of ketotifen taken orally 3 hours before exercise, and likewise DSCG was compared to a placebo powder inhaled with a spinhaler, and ketotifen with placebo tablets. The whole study lasted from January to March. Ten minutes after exercise the following changes in FEV1 (in percent of control value measured before exercise) were seen: after inhalation of a placebo powder the FEV1 decreased to 66% with an almost equal decrease after taking placebo tablets (67%) (0.45 greater than p greater than 0.40) whereas, in comparison, the decrease in FEV1 after DSCG (84%) is smaller than that after inhalation of a placebo powder (66%) (p less than 0.0025). In contrast to these results was the equal decrease in FEV1 after ketotifen (70%) (0.35 greater than p greater than 0.30) and placebo tablets (67%). Although a relatively high chosen dosage of ketotifen was given, it does not seem capable of inhibiting mediator release from the bronchial mast-cells as DSCG does. It is concluded that ketotifen given orally 3 hours before the exercise test is not effective against exercise-induced asthma.