Calcium channel blockers for heart attack and unstable angina

Examples

Generic Name	Brand Name
amlodipine besylate	Caduet [also contains atorvastatin, a cholesterol-lowering medicine], Norvasc
diltiazem	Cardizem, Tiazac
felodipine	Plendil
nifedipine	Adalat
verapamil	Verelan, 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 are useful in lowering blood pressure, controlling symptoms, and treating complications of a heart attack (such as arrhythmias). They may also be used if you cannot tolerate a beta-blocker.

But studies indicate short- and intermediate-acting calcium channel blockers may increase the risk of death and have raised doubts about using these medicines in some people.¹ A U.S. National Heart, Lung, and Blood Institute panel recommends that short-acting nifedipine should be used with great caution (if at all), especially at higher doses, in the treatment of high blood pressure, angina, and heart attack.

How Well It Works

Calcium channel blockers may help reduce the severity and frequency of chest pain when beta-blockers cannot be used.² But unlike beta-blockers, these medicines have not been proven to reduce the risk of a heart attack, future heart problems, or death.³

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.

Nifedipine, verapamil, and diltiazem 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

Calcium channel blockers are most effective when they are combined with nitrates and beta-blockers, but their dosage must be monitored carefully to prevent side effects.

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

Verapamil, diltiazem, and nifedipine may make heart failure worse. Amlodipine, felodipine, and nisoldipine are less likely to make heart failure worse.

Nifedipine, amlodipine, and felodipine are used most commonly in people who are already taking beta-blockers.

Verapamil or diltiazem sometimes is used when you cannot take beta-blockers.

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Author:	Robin Parks, MS	Last Updated: February 26, 2008
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
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