Examples

How It Works

These medicines work by reducing the amount of narrowing (constriction) of the blood vessels. This makes it easier for blood to flow through the vessels and lowers blood pressure.

Diltiazem and verapamil also slow the heart rate and affect the pumping action of the heart.

Why It Is Used

Calcium channel blockers may be used for high blood pressure either alone or with a diuretic, beta-blocker, or other agent.

Calcium channel blockers:

• Are especially effective in African Americans, older adults, and people who have a difficult time reducing their sodium intake.
• May help control angina in people with high blood pressure and coronary artery disease.

How Well It Works

These drugs lower blood pressure. They also relax the coronary arteries, which supply blood to the heart muscle, and may be prescribed for people who have angina caused by coronary artery disease. Medicines commonly used for these conditions include nicardipine, diltiazem, nifedipine, amlodipine, and verapamil. Amlodipine combined with atorvastatin is used to lower cholesterol as well.

Side Effects

Usually, calcium channel blockers cause very few side effects.

Possible side effects of all medicines listed above include:

• Dizziness, headache, redness in the face (flushing).
• Fluid buildup in legs (peripheral edema).
• Rapid heart rate.

Side effects that are more common with diltiazem and verapamil include:

• Slow heart rate.
• Constipation.

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

What To Think About

People who have irregular heartbeats (arrhythmias) or heart failure may need to be monitored closely when using certain calcium channel blockers. Because they affect heart rhythm, diltiazem and verapamil should be used with caution in people who have problems with the electrical system that regulates heart rate.

Calcium channel blockers are used alone or in combination with diuretics, beta-blockers, statins, or other agents. But diltiazem and verapamil must be used with caution in people who also are taking a beta-blocker. Using these medicines together can slow the heart rate too much and affect the system that regulates heart rate. Some calcium channel blockers can occasionally make heart failure worse.

Combining a calcium channel blocker with an angiotensin-converting enzyme (ACE) inhibitor may reduce symptoms of fluid buildup (edema) in people who develop this side effect.

It is important to take high blood pressure medicines daily as prescribed. Because high blood pressure often has no symptoms, it is easy to forget to take the pills.

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