Which drug antagonizes acetylcholine receptors to produce bronchodilation?

Ipratropium is a medication that works as an anticholinergic agent, effectively antagonizing acetylcholine receptors. In the context of bronchodilation, it specifically blocks the action of acetylcholine at the muscarinic receptors in the airways, which leads to smooth muscle relaxation and dilation of the air passages. This makes it particularly useful in managing conditions like asthma and chronic obstructive pulmonary disease (COPD).

Unlike other choices, Ipratropium does not stimulate beta receptors; rather, it directly blocks the bronchoconstrictive effects of acetylcholine, providing a complementary approach to other bronchodilators. The actions of Ipratropium are particularly beneficial for patients who may not tolerate or respond well to beta-agonists, as it helps reduce mucus secretion and bronchoconstriction without the cardiovascular side effects associated with other medications.