Source:http://linkedlifedata.com/resource/umls/id/C0717386
NCI: A combination of albuterol and ipratropium with a bronchodilatory effect. Albuterol stimulates beta-2 adrenergic receptors in the lungs, thereby activating the enzyme adenylate cyclase that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3',5'- adenosine monophosphate (cAMP). This results in the relaxation of bronchial smooth muscle, relieve of bronchospasms, and reduction of inflammatory cell mediator release. Ipratropium is a synthetic quaternary ammonium compound and a competitive muscarinic acetylcholine (Ach) receptor antagonist. This agent inhibits vagally mediated reflexes by antagonizing the action of Ach and consequently, prevents the increase in intracellular cyclic guanosine monophosphate, which is a result of ACh interacting with the muscarinic receptor on bronchial smooth muscle.