====== Dihydropyridine Calcium Channel Blockers ======

Dihydropyridine Calcium Channel Blockers (DHP CCBs) are potent arterial vasodilators that reduce systemic vascular resistance (SVR) by blocking L-type calcium channels in vascular smooth muscle.

They are primarily used for:

• Hypertension  
• Stable angina  
• Vasospastic (Prinzmetal) angina  

DHP CCBs primarily affect blood vessels, not cardiac conduction.

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

DHP CCBs:

• Block L-type calcium channels in vascular smooth muscle  
• Decrease intracellular calcium  
• Cause arteriolar vasodilation  

Net Effects:

• ↓ Systemic vascular resistance (afterload)  
• ↓ Blood pressure  
• Mild reflex ↑ heart rate (possible)  

Minimal direct effect on:
• SA node  
• AV node  
• Cardiac contractility  

Contrast with:
• [[cardio:ccb:non_dhp|Non-Dihydropyridine Calcium Channel Blockers]]

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===== Common DHP CCBs =====

  * • [[cardio:ccb:amlodipine|Amlodipine]]  
  * • [[cardio:ccb:nifedipine|Nifedipine]]  
  * • [[cardio:ccb:felodipine|Felodipine]]  
  * • [[cardio:ccb:nicardipine|Nicardipine]]  
  * • [[cardio:ccb:clevidipine|Clevidipine]]  

Most outpatient hypertension management uses:
→ [[cardio:ccb:amlodipine|Amlodipine]]

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===== Indications =====

==== Hypertension ====

  * • First-line therapy  
  * • Effective in Black patients  
  * • Often combined with [[cardio:raas:acei|ACE Inhibitors]] or [[cardio:raas:arb|ARBs]]

→ [[cardio:hypertension:start|Hypertension Module]]

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==== Stable Angina ====

• Reduce afterload  
• Improve myocardial oxygen supply-demand balance  

→ [[cardio:angina:start|Anti-Anginal Module]]

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==== Vasospastic (Prinzmetal) Angina ====

• First-line therapy  
• Relieve coronary artery spasm  

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==== Hypertensive Emergency (IV agents) ====

  * • [[cardio:ccb:nicardipine|Nicardipine]]  
  * • [[cardio:ccb:clevidipine|Clevidipine]]  

Used for rapid BP control.

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===== Adverse Effects =====

• Peripheral edema (dose-dependent)  
• Flushing  
• Headache  
• Reflex tachycardia (short-acting agents)  
• Gingival hyperplasia (rare)  

Edema is due to preferential arteriolar dilation without venous dilation.

Adding a [[cardio:raas:acei|RAAS blocker]] may reduce edema.

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===== Contraindications / Cautions =====

Use caution in:

  * • Severe hypotension  
  * • Advanced aortic stenosis  

Generally safe in:

• HFrEF (amlodipine acceptable)  

Unlike:

• [[cardio:ccb:non_dhp|Non-DHP CCBs]] which may worsen systolic HF.

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===== DHP vs Non-DHP Summary =====

DHP CCBs:
  * • Vascular selective  
  * • Strong BP reduction  
  * • Minimal conduction effect  

Non-DHP CCBs:
  * • Affect SA/AV node  
  * • Reduce heart rate  
  * • Used in arrhythmias  

See:
→ [[cardio:ccb:non_dhp|Non-DHP Calcium Channel Blockers]]

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

  * ✔ Potent arteriolar vasodilators  
  * ✔ First-line for hypertension  
  * ✔ Excellent in Black patients  
  * ✔ Peripheral edema is common  
  * ✔ Safe in HFrEF (amlodipine)  
  * ✔ Do not use short-acting nifedipine in hypertensive emergencies  

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Related:

→ [[cardio:ccb:start|Calcium Channel Blockers Overview]]  
→ [[cardio:hypertension:start|Hypertension Module]]  
→ [[cardio:angina:start|Anti-Anginal Module]]  
→ [[cardio:intro:start|Return to Cardiovascular Modules]]