Examples

Generic Name	Brand Name
diltiazem	Cardizem, Cartia, Dilacor, Taztia, Tiazac
verapamil	Calan, Covera, Isoptin, Verelan

How It Works

Certain calcium channel blockers help slow the heart rate by reducing the number of electrical impulses that pass through the atrioventricular (AV) node into the lower heart chambers (ventricles).

Why It Is Used

Diltiazem and verapamil are used to treat people with irregular or fast heartbeats. They can also be used to treat chest pain (angina) caused by hardening of the arteries in the heart (coronary artery disease) and high blood pressure.

How Well It Works

Certain calcium channel blockers (diltiazem and verapamil) can help slow a rapid heart rate. These may be used in people with asthma who cannot take beta-blockers. Other calcium channel blockers have little or no effect on heart rate or may actually increase it.

Side Effects

Side effects vary, depending on the individual drug, but they may include:

• Slow heart rate.
• Flushing, a pounding sensation in the head, dizziness, and headache.
• Constipation.
• Leg swelling.
• Decreased blood pressure, and heart failure that gets worse.
• Tingling sensations in the arms or legs.
• Weakness.

Diltiazem and verapamil may also cause a skin rash.

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

What To Think About

Diltiazem and verapamil can sometimes trigger heart failure or make it worse.

Calcium channel blockers and beta-blockers are usually the first medicines used to control heart rate. Digoxin may be used if calcium channel blockers and beta-blockers are not effective, if a person cannot tolerate these medicines because of low blood pressure, or if underlying heart disease requires their use.

If you have Wolff-Parkinson-White (WPW) syndrome and new atrial fibrillation, verapamil can make your tachycardia worse.

When beta-blockers and verapamil and/or digoxin are used together, they may further slow your heart rate and should be used with caution.

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