Which of the following is the drug of choice to reverse bronchoconstriction in an acute asthma attack?
(A) albuterol
(B) aminophylline
© cromolyn
(D) ipratropium
(E) salmeterol
Explanation:
(A) Inhaled albuterol (or other beta-2-selective receptor agonists including bitolterol,
metaproterenol, pirbuterol, and terbutaline) are the usual agents of choice for treating bronchoconstriction in an acute asthma attack. These beta-2-selective agonists produce bronchial relaxation by stimulating cyclic AMP (cAMP) formation in bronchiolar smooth muscle and cause less tachycardia than nonselective beta agonists. Unfortunately, they do cause some tachycardia and skeletal muscle tremor. Aminophylline (choice B) and other methylxanthines are rarely used to terminate acute episodes of asthma because they must be administered parenterally for rapid onset of effect. Cromolyn sodium (choice C) must be used prophylactically to preventacute episodes and probably acts by stabilizing mast cells. It is not a smooth muscle relaxing agent and is not effective in reversing bronchospasm. Inhaled ipratropium (choice D) has less general efficacy in acute attacks than beta agonists. Salmeterol (choice E) is an effective beta-2selective agonist but has a slow onset and long duration of action. Therefore, it is used for prophylaxis, not treatment of acute attacks.