Question

Given below are two statements:
Statement I: Verapamil is phenyl alkylamine in chemical nature.
Statement II: Nifedipine is dihydropyridine in chemical nature.
In light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

Remember the three chemical classes of Calcium Channel Blockers:
1. Phenylalkylamines $\rightarrow$ Verapamil (primarily cardiac action).
2. Dihydropyridines $\rightarrow$ Nifedipine/Amlodipine (primarily vascular action).
3. Benzothiazepines $\rightarrow$ Diltiazem (balanced cardiac/vascular action).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Calcium channel blockers (CCBs) are class IV antiarrhythmic and vasodilator agents that inhibit calcium ion influx through L-type voltage-gated calcium channels.
Chemically, CCBs are divided into three structurally and functionally distinct subclasses: phenylalkylamines, dihydropyridines, and benzothiazepines.

Step 2: Detailed Explanation:
Let us evaluate both statements:
1. Statement I: Verapamil is phenyl alkylamine in chemical nature.
This statement is correct.
Verapamil is the prototype drug of the phenylalkylamine class of calcium channel blockers.
Unlike dihydropyridines, verapamil exhibits significant cardioselectivity, acting directly on the myocardium and cardiac conducting tissue (SA and AV nodes).
This reduces heart rate, slows AV node conduction, and decreases cardiac contractility, making it an effective class IV antiarrhythmic agent.
Therefore, Statement I is true.
2. Statement II: Nifedipine is dihydropyridine in chemical nature.
This statement is correct.
Nifedipine is the prototype of the dihydropyridine class of calcium channel blockers.
This class exhibits high selectivity for vascular smooth muscle over cardiac tissue.
By blocking L-type calcium channels in the arterial wall, it causes marked peripheral vasodilation and decreases systemic vascular resistance.
Therefore, Statement II is true.
Both statements are correct and accurately describe the chemical classification of these clinically important calcium channel blockers.

Step 3: Final Answer:
Both Statement I and Statement II are true because verapamil is a phenylalkylamine and nifedipine is a dihydropyridine.
Therefore, the correct option is (A).