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.