Calcium Channel Blockers inhibit L-type calcium channels in cardiac and vascular smooth muscle.

They reduce intracellular calcium, leading to:

• ↓ Contractility
• ↓ Heart rate (some agents)
• ↓ Afterload

Used in:

• Hypertension
• Anti-Anginal Therapy
• Dysrhythmias

CCBs block L-type calcium channels.

Calcium normally:

• Enters cardiac myocytes during phase 2
• Triggers calcium-induced calcium release
• Enables actin-myosin contraction

Blocking calcium entry results in:

• Vasodilation
• Reduced myocardial contractility
• Reduced AV nodal conduction (non-DHP agents)

1. Dihydropyridines (DHP)

Primary effect:

• Vascular smooth muscle relaxation

Major action:

• ↓ Systemic Vascular Resistance
• ↓ Afterload

Common agents:

• Amlodipine
• Nifedipine
• Felodipine

Used primarily for:

• Hypertension
• Stable angina

Minimal effect on AV node.

2. Non-Dihydropyridines (Non-DHP)

Primary effect:

• Cardiac tissue

Major actions:

• ↓ Heart rate
• ↓ Contractility
• ↓ AV nodal conduction

Agents:

• Verapamil
• Diltiazem

Used for:

• Rate control in Dysrhythmias
• Angina
• Hypertension

DHP CCBs:

• Strong vasodilators
• Can cause reflex tachycardia
• Peripheral edema common

Non-DHP CCBs:

• Slow AV conduction
• Risk of bradycardia
• Avoid in HFrEF

Non-DHP CCBs:

• Avoid in Heart Failure with Reduced EF
• Avoid with beta-blockers (risk of heart block)

DHP CCBs:

• Use caution in severe hypotension

• All CCBs block L-type calcium channels
• DHP = vessels
• Non-DHP = heart
• Non-DHP slow AV node
• DHP reduce afterload
• Avoid non-DHP in HFrEF

• Hypertension
• Anti-Anginal Therapy
• Dysrhythmias
• Beta-Blockers
• Cardiovascular Pharmacology