Calcium Channel Blockers (CCBs)

Calcium channel blockers are approved for treating:

• high blood pressure,
• angina,
• abnormal heart rhythms (for example, atrial fibrillation, paroxysmal supraventricular tachycardia) and subarachnoid hemorrhage.

They are also used for treating other conditions such as:

• high blood pressure in the pulmonary arteries (pulmonary hypertension),
• Raynaud's phenomenon, cardiomyopathy (disease of the heart's muscle), and
• preventing migraine headaches.

Although calcium channel blockers have a similar mechanism of action, they differ in their ability to affect heart muscle vs. arteries, and they differ in their ability to affect heart rate and contraction. These differences determine how they are used and their side effects.

For example:

• verapamil (Covera-HS, Verelan PM, Calan), and diltiazem (Cardizem LA, Tiazac) reduce the strength and rate of the heart's contraction and are used in treating abnormal heart rhythms; and
• amlodipine (Norvasc) has very little effect on the heart rate and contraction. Therefore, amlodipine is not used for treating abnormal heart rhythm, but it is preferred when heart failure is present and dilation of arteries is desired.

Common side effects of calcium channel blockers include:

• headache,
• constipation,
• rash,
• nausea,
• flushing,
• edema (fluid accumulation in tissues),
• drowsiness,
• low blood pressure, and
• dizziness.

Sexual dysfunction, overgrowth of gums, and liver dysfunction also have been associated with calcium channel blockers. Verapamil (Covera-HS, Verelan PM, Calan) and diltiazem (Cardizem LA, Tiazac) worsen heart failure because they reduce the ability of the heart to contract and pump blood.

Calcium channel blockers interact with several drugs.

• Verapamil (Covera-HS, Verelan PM, Calan) and diltiazem (Cardizem LA, Tiazac) reduce the elimination and increase the blood levels of carbamazepine (Tegretol), simvastatin (Zocor), atorvastatin (Lipitor), and lovastatin (Mevacor). This can lead to toxicity from these drugs.
• Several calcium channel blockers [for example, diltiazem (Cardizem LA, Tiazac), felodipine (Plendil)] increase the level of cyclosporine (Sandimmune, Neoral, Restasis) and similarly lead to toxicity of cyclosporine.
• Grapefruit juice (1 glass, approximately 200ml) may elevate serum concentrations of verapamil (Covera-HS, Verelan PM, Calan), felodipine (Plendil), nifedipine (Adalat, Procardia), nicardipine (Cardene), nisoldipine (Sular), and possibly amlodipine (Norvasc).

The calcium channel blockers available in the U. S. are:

• amlodipine (Norvasc),
• diltiazem (Cardizem LA, Tiazac),
• felodipine (Plendil),
• isradipine (Dynacirc),
• nifedipine (Adalat, Procardia),
• nicardipine (Cardene),
• nimodipine (Nimotop),
• nisoldipine (Sular), and
• verapamil (Covera-HS, Verelan PM, Calan).

Verapamil, diltiazem and nicardipine (Cardene IV) also are available in intravenous formulations.

The calcium channel blockers available in the U. S. are:

• amlodipine (Norvasc),
• diltiazem (Cardizem LA, Tiazac),
• felodipine (Plendil),
• isradipine (Dynacirc),
• nifedipine (Adalat, Procardia),
• nicardipine (Cardene),
• nimodipine (Nimotop),
• nisoldipine (Sular), and
• verapamil (Covera-HS, Verelan PM, Calan).

Verapamil, diltiazem and nicardipine (Cardene IV) also are available in intravenous formulations.