Anticholinergic agents in chronic bronchitis and emphysema.

Inhaled anticholinergic agents produce as much absolute increase in airflow in chronic bronchitis as in asthma, namely about 0.2-0.3 litres increase in the FEV1 and a doubling of specific airways conductance. Their major advantage in bronchitis is due to the fact that adrenergic agents are relatively poor bronchodilators in this disorder. In bronchitis and emphysema a large number of studies suggest that anticholinergic agents not only are more potent than adrenergic agents but, when given in optimal dosage, achieve all of the available bronchodilatation in these patients. Possible reasons for this are suggested. Quaternary forms, such as ipratropium, have the additional advantage that they are poorly absorbed and thus produce no systemic side effects, giving them a very wide therapeutic margin. This makes them particularly suitable for the older population of which bronchitics are composed, and who are prone to side effects from atropine itself and from other classes of bronchodilators. They can be considered as first line therapy for the relief of symptoms on a day-to-day basis in this group of patients. They may also have a role in the management of acute exacerbations of airways disease, but this has not yet been fully established.