Adenosine-induced bronchoconstriction: premedication with chlorpheniramine and nedocromil sodium

The mechanism for adenosine-induced bronchospasm was investigated in asthmatic patients. Nedocromil sodium 4 mg given by aerosol 10 min before challenge effectively inhibited adenosine-induced bronchospasm. The H1-antagonist chlorpheniramine 4 mg given orally 1 h before challenge did not inhibit adenosine-induced bronchospasm, suggesting either that histaminergic pathways are not involved or that the dose was not sufficient to elicit an effect in the lung. Nedocromil sodium did not reduce the bronchial response to methacholine, supporting the view that adenosine-induced bronchospasm is not mediated through cholinergic pathways. The mechanism(s) by which nedocromil sodium inhibits the bronchial response requires further investigation.