Comments on acute studies.

Sixteen papers which have examined the effects of Duovent (a combination of fenoterol 200 micrograms and ipratropium bromide 80 micrograms) in the treatment and prevention of bronchospasm by acute studies are reviewed. The studies suggest that the use of a combination of anticholinergic and beta 2-adrenergic drugs is justified, because the dominant mechanism in bronchospasm is the effect of acetylcholine on muscarinic receptors and because ipratropium bromide increases the action of fenoterol, so as to obtain prolonged bronchospasmolytic and antibronchoconstrictive effects with halved doses of beta 2-agonist.