DOC for acute attack of asthma in patients on Beta blockers

Respiratory airway has beta adrenergic receptors(beta 2 receptors). Beta 2 agonists cause bronchodilatation, and beta 2 blockers cause bronchoconstriction. ipratropium bromide:- Atropine like drugs cause bronchodilatation by blocking M3 receptor mediated cholinergic constrictor tone; act primarily in the larger airways which receive vagal innervation. Ipratropium bromideis a sho acting (duration 4-6 hours) inhaled anticholinergic bronchodilator, while tiotropium bromide is long acting (duration 24 hours). They are the bronchodilators of choice in COPD. Ref:- kd tripathi;pg num:- 227,228