DHP Calcium Channel Blockers

Summary

Dihydropyridines are a class of Calcium Channel Blockers recognizable by their drug names that end in "-dipine". 

These drugs work by blocking voltage-dependent L-type calcium channels to cause smooth muscle relaxation. This primarily occurs in smooth muscle that lines the walls of blood vessels, resulting in vasodilation that preferentially dilates arteries more than veins.

Clinically, dihydropyridines are used to treat cases of vasospasm, such as in the treatment of subarachnoid hemorrhage, and the treatment of Raynaud’s Phenomenon. These drugs are also used to treat angina arising from ischemic or vasospastic causes. Importantly, dihydropyridines are commonly used to lower blood pressure in the treatment of hypertension, and they may even be given acutely to treat hypertensive emergencies. 

Side effects of dihydropyridines include edema or fluid retention, gingival hyperplasia, facial flushing, and dizziness.

Key Points

• Dihydropyridine (DHP) Calcium Channel Blockers
  • Drug Names
    • -dipine ending
      • Amlodipine
      • Clevidipine
      • Nicardipine
      • Nifedipine
      • Nimodipine
  • Mechanism
    • Act on Vascular Smooth Muscle
      • Contrast vs. Non-DHP Calcium Channel Blockers that primarily act on the heart
    • Block voltage-dependent L-type calcium channels
      • Decreases muscle contractility
    • Vasodilator (Causes Vasodilation)
      • Primarily functions at vascular smooth muscle to decrease smooth muscle contraction
      • Dilates Arteries > Veins
        • Contrast vs. Nitrates which primarily dilate the veins
  • Clinical Use
    • Hypertension
      • Preferential vasodilation at arterioles, which reduces systemic vascular resistance, leading to decreased blood pressure
      • Treats Hypertensive Emergency
        • Nicardipine and clevidipine are first-line agents
    • Angina (including vasospastic type)
      • Vasodilation counteracts coronary artery vasospasm
    • Raynaud phenomenon
      • Vasodilation counteracts peripheral vasospasm
    • Cerebral vasospasm
      • Vasodilation counteracts cerebral artery vasospasm, which often occurs as a response to bleeding
      • Nimodipine is indicated after subarachnoid hemorrhage
  • Adverse Effects
    • Gingival Hyperplasia
    • Peripheral Edema
      • Preferential vasodilation at arterioles leads to increased hydrostatic pressure at capillaries, leading to extravasation of fluid
    • Flushing
    • Dizziness