**Core Concept**
Ipratropium bromide is an anticholinergic medication that acts on muscarinic acetylcholine receptors in the lungs, leading to bronchodilation and relief of bronchospasm.

**Why the Correct Answer is Right**
Ipratropium bromide is a quaternary ammonium compound that selectively binds to M3 muscarinic receptors on smooth muscle cells in the airways, inhibiting acetylcholine-mediated contraction and leading to bronchodilation. This makes it a useful adjunct therapy for chronic obstructive pulmonary disease (COPD) and asthma. The medication is delivered via inhalation, allowing for local action with minimal systemic absorption.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as ipratropium bromide does not act on beta-adrenergic receptors, which are targeted by other bronchodilators like salbutamol.
**Option B:** This option is incorrect as ipratropium bromide is not a corticosteroid, which is a different class of medication used to treat asthma and COPD.
**Option C:** This option is incorrect as ipratropium bromide is not an antihistamine, which is used to treat allergic reactions.

**Clinical Pearl / High-Yield Fact**
Ipratropium bromide is often used in combination with beta-agonists like salbutamol to achieve additive bronchodilatory effects and improve lung function in patients with COPD and asthma.

**Correct Answer: C. Ipratropium bromide acts on muscarinic acetylcholine receptors in the lungs to produce bronchodilation and is used in the treatment of chronic obstructive pulmonary disease (COPD) and asthma.**