The Calcium Channel Blockers

Calcium channel blockers (also called calcium blockers, or calcium antagonists) reduce the ability of calcium to enter cardiac muscle cells and the cells of the blood vessel walls. These drugs tend to relax the walls of the blood vessels (which can lower the blood pressure), and slow the heart rate. Certain calcium channel blockers also can reduce the force of the heartbeat.

These drugs are often used to treat the following medical conditions:

• angina
• hypertension
• cardiac arrhythmias, especially atrial fibrillation
• migraine headaches

Currently Available Calcium Channel Blockers

• Amlodipine - Norvasc, also sold as Caduet and Lotrel
• Diltiazem - Cardizem, also sold as Dilacor and Tiazac
• Felodipine - Plendil
• Isradipine - DynaCirc
• Nicardipine - Cardene
• Nifedipine - Procardia XL, also sold as Adalat
• Nisoldipine - Sular
• Verapamil hydrochloride - Isoptin, also sold as Calan, Verelan, and Covera

Side Effects of Calcium Channel Blockers

The most common side effects of calcium channel blockers include:

• constipation
• rapid heart beat
• dizziness
• rash
• edema

In addition, calcium channel blockers that notably reduce the force of the heart beat should be avoided in people who have heart failure. These drugs include verapamil and diltiazem.

_{Abernethy DR, Schwartz JB. Calcium-antagonist drugs. N Engl J Med 1999; 341:1447.}