DOSE-RESPONSE STUDY OF OXITROPIUM BROMIDE INHALED AS A NEBULIZED SOLUTION

Twelve patients suffering from partially reversible chronic obstructiv e pulmonary disease (COPD) took past in a single blind, randomised, 4- way cross-over trial to determine the optimal dose and duration of act ion of the anticholinergic agent oxitropium bromide (OTB) inhaled as a nebulised solution. Single doses of 500, 1000, 1500 and 2000 mu g neb ulised OTB were compared during a 6 hour-observation period. Lung func tion test results indicated that 500 and 1000 mu g OTB only induced sl ight bronchodilatation, whereas 1500 and 2000 mu g OTB produced a sign ificantly greater increase in mean FEV1 compared to 500 mu g. There wa s a trend for 2000 mu g to be superior to 1000 mu g, but 2000 mu g and 1500 mu g were not significantly different. Significant bronchodilata tion (> 15 % rise in FEV1 from baseline) persisted for 6 h after 1500 mu g A significant decrease in airway resistance (Raw) was observed fo llowing inhalation of 2000 mu g The mean decrease in Raw was 33 % afte r 30 min, 20 % after 4 h and 12 % after 6 h. In this trial, 2000 mu g OTB administered by an ultrasonic nebuliser was the optimal dose, but a satisfactory result was also obtained with 1500 mu g.