Potential usefulness of inhibiting neural mechanisms in asthma

The airway innervation consists of a cholinergic system, an adrenergic system, and a non-adrenergic, non-cholinergic (NANC) system. Anticholinergic drugs have long since been used in the treatment of asthma and chronic obstructive pulmonary disease (COPD). The new anticholinergic drug, tiotropium bromide, causes long-lasting bronchodilatation (> or = 24 h) in patients with COPD. The sensory airway neuropeptides, substance P (SP) and neurokinin A (NKA), are potent contractors of smooth muscle, vasodilators and have important proinflammatory effects. Their airway effects are mediated by tachykinin NK1 and NK2 receptors. Antagonists for these receptors are currently being developed as a possible treatment of obstructive airway diseases.