A 55–year–old female who is taking propranolol for the management of a cardiovascular disease experiences an acute asthmatic attack. Which of the following drugs would you prescribe to attenuate this asthmatic attack

Inhaled β2 agonists are the agents of choice for termination of acute attack of bronchial asthma. However, as the patient is receiving β-blockers, treatment with β2 agonists will be ineffective (receptors are already blocked). Therefore, other bronchodilators like anticholinergic agents (ipratropium) or methylxanthines (theophylline) will be useful in such a case.