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Calcium channel blocker 

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Overview of Calcium channel blocker

Calcium channel blocker (CCB) is a drug that blocks the entry of calcium into the muscle cells of the heart and the arteries. The entry of calcium into these cells causes the heart to contract and the arteries to narrow. By blocking the entry of calcium, the contraction rate of the heart can be decreased and the arteries can be dilated.

Effects of calcium channel blocker

Calcium channel blockers have the following four cardiovascular effects:

  • Peripheral vasodilatation 
  • Negative chronotropy (decreased heart rate) 
  • Negative inotropy (decreased cardiac contractility) 
  • Negative dromotropy (decreased cardiac conduction)


Uses of Calcium channel blocker

Cardiovascular uses

Angina pectoris: This condition occurs when the supply of oxygen to the heart is inadequate in comparison to the amount of work the heart must do. calcium channel blockers reduce the pressure of the arteries by dilating them. As a result, the pumping activity of the heart becomes lot easier requiring less amount of oxygen. Read more details about Angina pectoris

High blood pressure: calcium channel blockers keep calcium from entering the muscle cells of the heart and blood vessels. This causes the blood vessels to relax and therefore the pressure goes down. Read more details about High blood pressure

Abnormal rapid heart rhythms: calcium channel blockers are used slow the rate at which the heart beats and are thereby used to treat abnormal rapid heart rhythm conditions like atrial fibrillation and paroxysmal supraventricular tachycardia. Read more details about Arrythmia

Heart attack: calcium channel blockers are also given to patients after a heart attack. CCBs are usually given to patients who cannot tolerate beta-blocking drugs, have atrial fibrillation, or angina. However, unlike beta blockers, CCBs neither reduce the mortality rate nor the chance of additional heart attacks after a heart attack. Read more details about Heart attack


Other Uses

calcium channel blockers are also used for treating:

  • Subarachnoid haemorrhage 
  • Reynaud’s syndrome  
  • Cardiomyopathy


Different Classes of calcium channel blockers

The CCBs are of three classes of CCBs. They differ from each other on the basis of their basic chemical structure as well as their relative selectivity toward cardiac versus vascular L-type calcium channels.

Dihydropyridines: These have high vascular selectivity and are primarily used to reduce systemic vascular resistance and arterial pressure. These are primarily used to treat hypertension. However, these are not used to treat angina because of their powerful systemic vasodilator and pressure lowering effects, which may lead to reflex cardiac stimulation (tachycardia and increased inotropy). Moreover, these effects can dramatically increase the myocardial oxygen demand.

The available dihydropyridines are:

  • Amlodipine
  • Felodipine
  • Isradipine
  • Nicardipine
  • Nifedipine
  • Nimodipine
  • Nitrendipine
Non-dihydropyridines: These include the other two classes of CCBs:

Verapamil (phenylalkylamine class): This drug is used for treating angina and arrhythmias. It reduces myocardial oxygen demand and reverses coronary vasospasm.

Diltiazem (benzothiazepine class): This drug has both cardiac depressant and vasodilator actions. It is used to reduce arterial pressure without producing the same degree of reflex cardiac stimulation caused by dihydropyridines.


Common side effects

The most common side effects of CCBs are:

  • Rash 
  • Edema (swelling of the legs with fluid) 
  • Liver dysfunction and over growth of gums may also occur
However, drugs like diltiazem (Cardizem) or verapamil (Calan, Isoptin) should be carefully administered as when given to individuals with heart failure, symptoms of heart failure may worsen. This is because these drugs reduce the ability of the heart to pump blood. Like other blood pressure medications, CCBs are also associated with sexual dysfunction.

Written by: Healthplus24 team
Date Last Updated: November 02, 2012