Review Question - QID 210580

This patient with dyspnea, accessory muscle recruitment, and wheezing most likely has asthma and was prescribed the muscarinic antagonist ipratropium. Glycopyrrolate is another muscarinic antagonist.

Muscarinic receptors are a subtype of cholinergic receptors that are primarily found in the central nervous system, the autonomic nervous system, and a variety of smooth muscles. Selectively targeting these receptors with muscarinic antagonists can lead to a diverse array of organ specific functions. For example, the respiratory muscarinic antagonists ipratropium and tiotropium lead to bronchodilation and can be used in the treatment of both asthma and chronic obstructive pulmonary disease. Similarly, glycopyrrolate is a urinary specific muscarinic antagonist that can reduce bladder spasms.

Incorrect Answers:
Answer 1: Cortisol is a corticosteroid that is similar in effect to the asthma drug fluticasone; however, this drug does not directly inhibit smooth muscle.

Answer 3: Isoproterenol is a non-selective beta adrenergic agonist that is similar in effect to the asthma drug albuterol; however, this drug is an agonist rather than an inhibitor.

Answer 4: Theophylline is a methylxanthine that can be used in asthmas and in COPD; however, this drug does not function as a muscarinic antagonist.

Answer 5: Zileuton is a leukotriene production inhibitor that is similar in effect to montelukast; however, this drug does not cause direct inhibition of a smooth muscle receptor.

Bullet Summary:
Muscarinic inhibitors can have organ specific actions such as the effect of ipratropium in the treatment of asthma.