Calcium channel blockers are typically prescribed to treat high blood pressure, chest pain and irregular heart rhythm. They may be used to treat cardiomyopathy, which is a disease that causes the heart muscles to become weak and inflamed. Common calcium channel blockers include amlodipine, felodipine, isradipine, nicardipine, nifedipine, nisoldipine, diltiazem and verapamil. Your physician can determine which calcium channel blocker is right for you.
Cardiomyopathy
Calcium channel blockers treat a type of cardiomyopathy called hypertrophic cardiomyopathy. In hypertrophic cardiomyopathy, the heart muscle thickens, or hypertrophies. This causes difficulty in pumping blood and, in some cases, can obstruct blood flow. Even though many individuals have few or no symptoms, these can include shortness of breath, dizziness, fainting, chest pain and heart palpitations. With proper treatment, the condition does not cause significant health problems.
Actions of Calcium Channel Blockers
Calcium channel blockers block calcium from entering the heart cells as well as the walls of blood vessels, resulting in a reduction in the heart's oxygen requirement. It also relaxes the smooth muscle in the heart, allowing blood vessels to relax and expand. The heart does not have to work as hard to pump blood through the body. These medications therefore treat not only cardiomyopathy but its complications, such as chest pain and irregular heart rhythms.
Side Effects
Headache is the most common side effect seen with most of the calcium channel blockers. According to the "Drug Information Handbook," isradipine, nisoldipine and nifedipine cause headache in more than 20 percent of patients, and diltiazem, felodipine, verapamil and nicardipine can cause headache in up to 15 percent of patients. Other common side effects include dizziness, fatigue, abdominal discomfort, nausea, constipation and flushing, which is redness of the face and skin. The calcium channel blockers may cause edema, or water retention, which can result in swelling of the legs and feet. This side effect is dose-related: the higher the dose, the greater the likelihood of developing it. Contact your physician if you develop this adverse effect.
Warnings
Grapefruit juice can result in increased blood levels of calcium channel blockers. Avoid grapefruit and grapefruit juice during the course of therapy. Elderly patients should receive a low dose of the calcium channel blocker initially, which may then be adjusted according to response. Elderly patients should be monitored more carefully, because response may be enhanced; this can result in increased side effects.
References
- American Heart Association: Cardiomyopathy
- "Drug Information Handbook"; Charles F. Lacy, Lora L. Armstrong, et al.; 2009
- MayoClinic.com: Hypertrophic Cardiomyopathy
- MayoClinic.com: Calcium Channel Blockers
- "Basic and Clinical Pharmacology"; Bertram G. Katzung; 2007
