====== Calcium Channel Blockers (CCBs) ======

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:

  * [[cardio:hypertension:start|Hypertension]]
  * [[cardio:angina:start|Anti-Anginal Therapy]]
  * [[cardio:arrhythmias:start|Dysrhythmias]]

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===== Mechanism of Action =====

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)

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===== Two Major Classes =====

1. [[cardio:ccb:dhp|Dihydropyridines (DHP)]]

Primary effect:
  * Vascular smooth muscle relaxation

Major action:
  * ↓ Systemic Vascular Resistance
  * ↓ Afterload

Common agents:
  * [[cardio:ccb:amlodipine|Amlodipine]]
  * [[cardio:ccb:Nifedipine]]
  * [[cardio:ccb:Felodipine]]

Used primarily for:
  * [[cardio:hypertension:start|Hypertension]]
  * [[cardio:angina:start|Stable angina]]

Minimal effect on AV node.

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2. [[cardio:ccb:non_dhp|Non-Dihydropyridines (Non-DHP)]]

Primary effect:
  * Cardiac tissue

Major actions:
  * ↓ Heart rate
  * ↓ Contractility
  * ↓ AV nodal conduction

Agents:
  * [[cardio:ccb:verapamil|Verapamil]]
  * [[cardio:ccb:diltiazem|Diltiazem]]

Used for:
  * Rate control in [[cardio:arrhythmias:start|Dysrhythmias]]
  * [[cardio:angina:start|Angina]]
  * Hypertension

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===== Clinical Differences =====

DHP CCBs:
  * Strong vasodilators
  * Can cause reflex tachycardia
  * Peripheral edema common

Non-DHP CCBs:
  * Slow AV conduction
  * Risk of bradycardia
  * Avoid in HFrEF

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===== Contraindications =====

Non-DHP CCBs:

  * Avoid in [[cardio:heart_failure:start|Heart Failure with Reduced EF]]
  * Avoid with beta-blockers (risk of heart block)

DHP CCBs:

  * Use caution in severe hypotension

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===== Clinical Pearls =====

  * 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

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===== Related =====

  * [[cardio:hypertension:start|Hypertension]]
  * [[cardio:angina:start|Anti-Anginal Therapy]]
  * [[cardio:arrhythmias:start|Dysrhythmias]]
  * [[cardio:beta_blockers:start|Beta-Blockers]]
  * [[cardio:intro:start|Cardiovascular Pharmacology]]