• Clinical science

Calcium channel blockers

Abstract

Calcium channel blockers (CCBs) are drugs that bind to and block the L-type calcium channel. The L-type channels are the predominant calcium channels in the myocardium and the vascular smooth muscles. By blocking these channels, CCBs cause peripheral arterial vasodilation and myocardial depression, which leads to a drop in blood pressure and negative chronotropic, inotropic, and dromotropic effects on the myocardium. The most common indications for CCB use are hypertension, angina, and supraventricular arrhythmias. CCBs are also beneficial in the treatment of cardiomyopathy, thromboangiitis obliterans, Raynaud's phenomenon, and cluster headaches. CCBs are divided into three classes based on their effects: dihydropyridines (e.g., nifedipine, amlodipine) are potent vasodilators, phenylalkylamines (verapamil, gallopamil) are potent myocardial depressants, and benzothiazepines (diltiazem) are moderate vasodilators and myocardial depressants. The main side effects of dihydropyridines are caused by vasodilation (headaches, peripheral edema, reflex tachycardia), and those of phenylalkylamines by myocardial depression (bradyarrhythmias, atrioventricular block). The side effects of benzothiazepines are generally similar but milder compared to those of the other CCB classes. CCBs are contraindicated in patients with pre-existing cardiac conduction disorders (e.g., atrioventricular block, sick sinus syndrome), symptomatic hypotension, and acute coronary syndrome.

Overview

Class of CCB Examples Effects
Dihydropyridines [1][2]
  • Potent vasodilator
  • Minimal myocardial depressant activity
Non-dihydropyridine CCBs Benzothiazepines
  • Moderate vasodilator
  • Moderate myocardial depressant activity
Phenylalkylamines

References:[3]

Effects

Side effects

Dihydropyridines

  • Effects due to vasodilation
    • Peripheral edema (esp. amlodipine)
    • Headaches, dizziness
    • Facial flushing, feeling feverish
    • Reflex tachycardia (esp. nifedipine)
      • May worsen symptoms of angina
  • Gingival hyperplasia

Benzothiazepines

  • Side effects similar to the other classes of CCBs, but milder

Phenylalkylamines

Phenylalkylamines (verapamil) primarily affect the calcium channels of the heart and are contraindicated in cases of heart failure because of their negative effect on myocardial contractility!
References:[4][5][6][7][8][9][10]

We list the most important adverse effects. The selection is not exhaustive.

Indications

References:[11]

Contraindications


References:[12][4][5][13][14][15][16][17][18][19][20][21]

We list the most important contraindications. The selection is not exhaustive.