Prevention of fog-induced bronchospasm by Duovent and its components (fenoterol, ipratropium bromide) in asthmatics

Abstract

16 hyperreactive asthmatics were challenged with an ultrasonic mist of H2O at the same time of day on 4 usually consecutive days 2 h after premedication with placebo, fenoterol (200 micrograms), ipratropium bromide (80 micrograms) and Duovent (fenoterol 200 micrograms + ipratropium bromide 80 micrograms), given in random order and double-blind conditions. The challenge test consisted of 3 exposures of 30, 60 and 120 s with 4-min intervals. Specific airway resistance (sRaw) was measured under basal conditions and 1, 2 and 3 min after each exposure. FEV1 was measured under basal conditions and immediately after the last sRaw measurement. Fenoterol afforded a good protection; ipratropium bromide alone was ineffective but enhanced the protective effect of fenoterol when the two drugs were given in combination (Duovent). A similar effect was also observed after a second challenge performed 1 h (9 patients) or 3 h (6 patients) after the first one, which was performed 2 h after premedication.