Anticholinergics in acute bronchial asthma.

Studies in both animals and man suggest a role for cholinergically-mediated reflex bronchoconstriction in the airflow limitation of asthma. Muscarinic cholinergic antagonists such as atropine, ipratropium bromide (IB) and oxitropium bromide (OB) when delivered locally to the airways are bronchodilators and antibronchoconstrictors. Although drugs like IB and OB offer advantages over some of the older anticholinergic preparations in terms of pharmacokinetics and therapeutic ratio, they cannot be considered as first line drugs in the therapy of acute asthma. However, when used in combination with other anti-asthma drugs, therapeutic benefit of inhaled IB and OB is obtained by maximising the bronchodilator properties of the individual drugs without attendant systemic side effects. Finally, the removal of the preservatives EDTA and benzylchonium chloride from Atrovent nebulizer solution has removed the risk of paradoxical bronchoconstriction occurring.