Albuterol is a beta-2 adrenergic receptor agonist used to treat reactive airway disease and bronchospasm. The beta-2 receptor is the dominant receptor in the bronchial smooth muscle. Activation of these receptors causes adenylyl cyclase to convert ATP to cAMP leading to a chain of intracellular events that ultimately lead to decrease in the concentration of intracellular calcium and activation of protein kinase A. Both of these changes inactivate myosin light-chain kinase and activate myosin light-chain phosphatase, ultimately resulting in bronchial smooth muscle relaxation. Increased cAMP leads to inhibition of inflammatory cells such as eosinophils, basophils, and mast cells.
Ipratropium is a non-specific muscarinic antagonist that also causes bronchial smooth muscle relaxation in the small and medium airways. Ipratropium bromide is a quaternary ammonium compound obtained by the chemical combination of atropine and isopropyl bromide. Ipratropium works by opposing cholinergic action on bronchial smooth muscle. It promotes the degradation of cyclic guanine monophosphate resulting in decreased intercellular cGMP. As cholinergic activation leads to bronchoconstriction and mucous secretion, ipratropium results in decreased bronchoconstriction, and mucous secretion. Secondary to its quaternary structure, ipratropium does not diffuse into the blood and does not cross the blood-brain barrier.
1. Lemke, T.L.; Williams, D.A; Roche, V.F.; Zito, S.W. (2013) Foye’s Principles of Medicinal Chemistry. Philadelphia, PA: Lippincott Williams & Wilkins. Pp 1314-1320.
2. Hamilton, Richart (2015) Tarascon Pocket Pharmacopoeia 2015 Lab-Coat Edition. Jones & Bartlett Learning. p 455.
Percentage correct: 89%
Year asked: 2011