U01.07.065 Antianginal therapy

Calcium channel blockers (CCBs) are a class of medications commonly used to treat cardiovascular conditions by inhibiting the influx of calcium through L-type calcium channels. The two main subclasses of CCBs are dihydropyridines and non-dihydropyridines, each with distinct mechanisms of action and clinical applications.

Mechanism of Action

CCBs block L-type calcium channels in both cardiac and smooth muscle. This leads to a reduction in intracellular calcium levels, decreasing muscle contractility and causing relaxation of vascular smooth muscle as well as a reduction in cardiac contractility and conduction.

Vascular Smooth Muscle: Dihydropyridines (e.g., amlodipine, nifedipine) are more potent in dilating blood vessels, leading to a decrease in blood pressure.
Heart: Non-dihydropyridines (e.g., verapamil, diltiazem) have a more significant effect on the heart, decreasing heart rate, contractility, and conduction velocity.

Drug Classification and Comparison

Drug	Type	Primary Action Site	Effect on Vascular Smooth Muscle	Effect on Heart
Amlodipine	Dihydropyridine	Vascular Smooth Muscle	Strong (Most potent)	Minimal
Clevidipine	Dihydropyridine	Vascular Smooth Muscle	Strong	Minimal
Nicardipine	Dihydropyridine	Vascular Smooth Muscle	Strong	Minimal
Nifedipine	Dihydropyridine	Vascular Smooth Muscle	Strong	Minimal
Nimodipine	Dihydropyridine	Vascular Smooth Muscle	Moderate	Minimal
Diltiazem	Non-Dihydropyridine	Heart & Vascular Smooth Muscle	Moderate	Moderate
Verapamil	Non-Dihydropyridine	Heart & Vascular Smooth Muscle	Moderate	Strong (Most potent)

Clinical Uses

Dihydropyridines (except Nimodipine):

Hypertension: Used to lower blood pressure.
Angina: Effective for both classic and vasospastic angina.
Raynaud’s Phenomenon: Helps in vasodilation, improving blood flow.

Nimodipine:

Subarachnoid Hemorrhage: Prevents cerebral vasospasm post-subarachnoid hemorrhage.

Nicardipine and Clevidipine:

Hypertensive Urgency/Emergency: These agents are often used in acute situations to rapidly lower blood pressure.

Non-Dihydropyridines:

Hypertension: Effective in managing high blood pressure.
Angina: Reduces the frequency and severity of angina attacks.
Atrial Fibrillation/Flutter: Helps in rate control.

Adverse Effects

Class	Common Adverse Effects
Dihydropyridines	Peripheral Edema, Flushing, Dizziness
Non-Dihydropyridines	Cardiac Depression, AV Block, Hyperprolactinemia (verapamil), Constipation

Dihydropyridines:

Peripheral Edema: Due to vasodilation.
Flushing: Common due to blood vessel dilation.
Dizziness: Secondary to hypotension.

Non-Dihydropyridines:

Cardiac Depression: Reduced contractility and heart rate.
AV Block: Can slow or block electrical conduction through the AV node.
Hyperprolactinemia: Most commonly associated with verapamil.
Constipation: A frequent side effect of verapamil.

Points to Remember

Dihydropyridines (e.g., amlodipine, nifedipine) predominantly affect vascular smooth muscle, making them more effective for hypertension and angina.
Non-dihydropyridines (e.g., verapamil, diltiazem) have a greater impact on the heart and are used for arrhythmias (e.g., atrial fibrillation/flutter).
Nimodipine is uniquely used for preventing cerebral vasospasm after subarachnoid hemorrhage.
Adverse effects vary based on the class: Dihydropyridines cause more vascular side effects, while non-dihydropyridines are more likely to cause cardiac issues.

Your voice matters – comment below!Cancel reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

USMLE Step 1 Review Series

Curriculum

U01.07.065 Antianginal therapy

Mechanism of Action

Drug Classification and Comparison

Clinical Uses

Dihydropyridines (except Nimodipine):

Nimodipine:

Nicardipine and Clevidipine:

Non-Dihydropyridines:

Adverse Effects

Dihydropyridines:

Non-Dihydropyridines:

Points to Remember

Your voice matters – comment below!Cancel reply

Modal title