Calcium channel blocking agents in bronchial hyperreactivity.

A variety of clinical and animal bronchial challenge experiments have been undertaken to assess the efficacy and sites of action of the calcium channel blockers nifedipine and verapamil in blunting bronchoconstriction. Nifedipine appears to be the more effective of these agents, and it blunts the airways response to methacholine and histamine inhalation as well as the bronchoconstriction caused by exercise or cold air hyperpnea. The mechanism by which it acts is difficult to define with certainty because of the widely distributed role of calcium ion within the bronchoconstriction pathways, but nifedipine appears to exert a direct effect on airway wall smooth muscle as well as a possible influence on mast cell mediator release.