A comparison of three high doses of ipratropium bromide in chronic asthma.

We have performed a double-blind crossover study in nine patients with stable chronic asthma, in order to evaluate the effects of three doses of the anticholinergic bronchodilator ipratropium bromide (80 micrograms, 200 micrograms and 400 micrograms) given by metered dose inhaler. These doses are larger than the recommended dose (40 micrograms). All three doses of the drug produced significant bronchodilation from 15 minutes to 5 hours. Some small but statistically significant differences were found in favour of the 200 micrograms and 400 micrograms doses when compared with the 80 micrograms dose and the duration of action of the 400 micrograms dose was longer than that of 200 micrograms dose. The clinical usefulness of these small differences remains to be assessed.