Ipratropium Bromide (IB)

Ipratropium bromide is an anticholinergic drug used for the treatment of chronic obstructive pulmonary disease and acute asthma. It blocks the muscarinic acetylcholine receptors in the smooth muscles of the bronchi in the lungs, opening the bronchi. Ipratropium blocks muscarinic acetylcholine receptors, without specificity for subtypes, and therefore promotes the degradation of cyclic guanosine monophosphate (cGMP), resulting in a decreased intracellular concentration of cGMP. Most likely due to actions of cGMP on intracellular calcium, this results in decreased contractility of smooth muscle in the lung, inhibiting bronchoconstriction and mucus secretion. It is a nonselective muscarinic antagonist, and does not diffuse into the blood, which prevents systemic side effects. Ipratropium is a derivative of atropine but is a quaternary amine and therefore does not cross the blood–brain barrier, which prevents central side effects.