Combination therapy with anticholinergic agents for airflow obstruction.

The availability of long-acting, locally effective anticholinergic agents that can be delivered by aerosol and that have little systemic toxicity offers an alternative or additional form of therapy for relief of airflow obstruction. Most studies of combination therapy have examined the interaction of anticholinergic drugs with beta-adrenergic agents. For patients with asthma, combination treatment appears not to increase significantly the maximal bronchodilatation achievable with beta-agonists alone but does appear to prolong bronchodilatation and to permit reductions in the dose of beta-agonists without loss of efficacy. For patients with chronic obstructive bronchitis and emphysema, combination therapy may also increase the bronchodilatation achievable with beta-adrenergic agents alone. Anticholinergic agents have been shown also to increase the inhibitory effect of sodium cromoglycate on the bronchospastic response to exercise, eucapnic hyperpnoea and sulphur dioxide.