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cardio:ccb:nifedipine

Nifedipine

Nifedipine is a Dihydropyridine Calcium Channel Blocker (DHP CCB).

It primarily causes arterial vasodilation and reduces systemic vascular resistance.

Used in:

Calcium Channel Blockers


Mechanism of Action

Nifedipine blocks L-type calcium channels in vascular smooth muscle.

This leads to:

  • ↓ Intracellular calcium
  • Arterial vasodilation
  • ↓ Systemic Vascular Resistance
  • ↓ Afterload

Minimal direct effect on:

  • SA node
  • AV node
  • Myocardial contractility

Primary action = vascular.


Immediate-Release vs Extended-Release

Immediate-Release (short-acting):

  • Rapid vasodilation
  • Reflex tachycardia
  • Not recommended for chronic hypertension
  • Associated with increased risk of adverse cardiac events

Extended-Release (preferred):

  • Smooth 24-hour BP control
  • Lower risk of reflex tachycardia
  • Appropriate for chronic hypertension and angina

Extended-release formulations are standard in modern practice.


Hemodynamic Effects

  • ↓ Blood pressure
  • ↓ Afterload
  • Possible reflex tachycardia (especially short-acting form)

Does NOT significantly:

  • Slow heart rate
  • Depress AV conduction

Clinical Use

Hypertension:

Angina:

  • Reduces afterload
  • Improves oxygen supply-demand balance

Vasospastic Angina:

  • Coronary vasodilation

Raynaud Phenomenon:

  • Reduces vasospasm

Adverse Effects

Common:

  • Peripheral edema
  • Flushing
  • Headache
  • Reflex tachycardia (short-acting)

Mechanism of edema:

  • Arteriolar dilation without venodilation
  • Increased capillary hydrostatic pressure

Contraindications & Cautions

Avoid short-acting formulation in:

  • Unstable angina
  • Acute coronary syndromes

Use caution in:

  • Severe hypotension

Nifedipine vs Amlodipine

Amlodipine:

  • Longer half-life
  • Less reflex tachycardia
  • More gradual onset

Nifedipine:

  • Faster onset
  • Greater reflex tachycardia risk (short-acting)

Clinical Pearls

  • DHP CCB
  • Strong arterial vasodilator
  • Use extended-release for chronic therapy
  • Avoid short-acting form in CAD
  • Causes peripheral edema
  • No AV nodal slowing

cardio/ccb/nifedipine.txt · Last modified: by andrew2393cns