A 55-year-old female who is taking propanolol 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?

(Ref: KDT 6/e p222) Inhaled b2 agonists are the agens of choice for termination of acute attack of bronchial asthma. However, as the patient is receiving b-blockers, treatment with b2 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.