Calcium channel blockers for heart attack and unstable angina


Generic Name Brand Name
diltiazem Cardizem, Dilacor XR, Taztia, Tiazac
verapamil Calan, Isoptin SR

How It Works

Calcium channel blockers help treat chest pain and increase oxygen supply to the heart by:

  • Increasing blood flow to the heart muscle by relaxing (dilating) the coronary arteries.
  • Possibly helping to prevent spasm of the coronary arteries.
  • Lowering blood pressure and the workload on the heart, which allows the heart muscle to function with less oxygen and blood flow.
  • Sometimes slowing a rapid heart rate and controlling irregular heart rhythms.

Why It Is Used

Calcium channel blockers may be used to control symptoms and treat complications of a heart attack (such as arrhythmias). They may also be used if you cannot tolerate a beta-blocker.

How Well It Works

Calcium channel blockers may help reduce the severity and frequency of chest pain when beta-blockers cannot be used. But unlike beta-blockers, these medicines have not been proven to reduce the risk of a heart attack, future heart problems, or death.

Side Effects

Side effects vary depending on the drug but may include:

  • A slowed heart rate or irregular heart rhythm.
  • Flushing, a pounding sensation in the head, dizziness, or headache.
  • Leg and/or ankle swelling.
  • Decreased blood pressure.
  • Tingling sensations in the arms or legs.
  • Weakness.
  • Constipation.

Do not stop taking this medicine without first consulting your doctor.

Verapamil may cause a skin rash or breast enlargement.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

In general, the long-acting forms (taken once a day) of calcium channel blockers are preferred over the short-acting forms (taken 2 to 4 times a day).

Verapamil and diltiazem may make heart failure worse.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

Last Updated: May 5, 2009

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