The following antiarrhythmic drug has the most prominent anticholinergic action
**Core Concept**
Disopyramide is a Class IA antiarrhythmic drug that has a significant anticholinergic action, which can lead to various side effects such as dry mouth, blurred vision, and urinary retention.
**Why the Correct Answer is Right**
Disopyramide's anticholinergic action is primarily due to its ability to block the muscarinic receptors in the parasympathetic nervous system. This is achieved through its quinidine-like structure, which allows it to bind to the muscarinic receptors and reduce the effects of acetylcholine. As a result, disopyramide can cause a range of anticholinergic side effects, including dry mouth, constipation, and urinary retention.
**Why Each Wrong Option is Incorrect**
* **Option A:** Quinidine also has some anticholinergic activity, but it is not as pronounced as disopyramide's. Quinidine's primary mechanism of action is through the blockade of sodium channels.
* **Option B:** Lignocaine is a Class IB antiarrhythmic drug that primarily works by blocking sodium channels. It does not have significant anticholinergic activity.
* **Option D:** Procainamide is a Class IA antiarrhythmic drug that also has some anticholinergic activity, but it is not as pronounced as disopyramide's.
**Clinical Pearl / High-Yield Fact**
When prescribing disopyramide, it is essential to monitor patients for anticholinergic side effects, especially in elderly patients or those with pre-existing urinary retention or constipation.
✓ Correct Answer: C. Disopyramide