RESUMO
Exercise-induced bronchospasm (EIB) is the transient narrowing of the airways that follows vigorous exercise. Ipratropium bromide may be used to prevent EIB, but its effect varies among individuals. We hypothesized that time of administration of ipratropium interferes with its action. This was a prospective, double-blind, cross-over study carried out to evaluate the bronchoprotective and bronchodilatory effect of ipratropium at different times of day. The study consisted of 4 exercise challenge tests (2 at 7 am and 2 at 6 pm). In the morning, one of the tests was performed after placebo administration and the other one after ipratropium (80 microg) and the two tests (placebo and ipratropium) were repeated in the evening. Twenty-one patients with severe or moderate asthma and previous confirmation of EIB were enrolled in this prospective trial. The bronchodilatory effect of ipratropium was 0.25+/-0.21 L or 13.11+/-10.99% (p=0.001 compared to baseline values) in the morning, and 0.14+/-0.25 L or 7.25+/-11.37% (p>0.05) in the evening. In the morning, EIB was 0.58+/-0.29 L on the placebo day and 0.38+/-0.22 L on the treatment day (p=0.01). In the evening, EIB was 0.62+/-0.28 L on the placebo day and 0.51+/-0.35 L on the treatment day (p>0.05). We suggest that the use of ipratropium for the treatment of asthma and EIB should take into consideration the time of administration.