Modulation of non-specific bronchial reactivity.

There are several drugs that can modify non-specific reactivity induced by various stimuli. Disodium cromoglycate (DSCG) is able to reduce bronchial hyperreactivity status, but its mechanism has not yet been demonstrated. It would be expected to exert its activity either by mastocyte stabilization or by other actions that are not related to mastocyte mediator release. It has been suggested that DSCG has a calcium channel blocking activity. Its possible role as a calcium antagonist suggest a general modifying effect of calcium antagonists against hyperreactivity, although their use in therapy cannot be foreseen. In exercise-induced bronchospasm, numerous beta 2-adrenergic drugs have proved more effective than other drugs studied in several investigations. It is unknown whether their effects are to be attributed to a bronchodilator activity or to another mechanism of action. Anticholinergic drugs have a lower protective effect against several stimuli. Theophylline has protective action on histamine bronchospasm which is dependent on the blood levels of theophylline attained. Many drugs currently available can modify bronchial hyperreactivity, but only in a transient way. Several anti-asthmatic drugs cause a decrease of the bronchial hyperreactivity, reducing the release of inflammatory mediators and inhibiting reflex bronchoconstriction. However, at present there are no specific drugs which are able to modify bronchial hyperreactivity with a direct action.