Verelan

Definition

Calcium channel blockers are medicines that slow the movement of calcium into the cells of the heart and blood vessels. This, in turn, relaxes blood vessels, increases the supply of oxygen-rich blood to the heart, and reduces the heart's workload.

Purpose

Calcium channel blockers are used to treat high blood pressure, to correct abnormal heart rhythms, and to relieve the type of chest pain called angina pectoris. Physicians may prescribe some calcium channel blockers to treat panic attacks and bipolar disorder (manic depressive illness) and to prevent migraine headache.

Description

Calcium channel blockers are available only with a physician's prescription and are sold in tablet, capsule, and injectable forms. Some commonly used calcium channel blockers are amlopidine (Norvasc), diltiazem (Cardizem), isradipine (DynaCirc), nifedipine (Adalat, Procardia), and verapamil (Calan, Isoptin, Verelan).

Recommended dosage

The recommended dosage depends on the type, strength, and form of calcium channel blocker and the condition for which it is prescribed. Check with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage.

Always take calcium channel blockers exactly as directed. Never take larger or more frequent doses, and do not miss any doses. This medicine may take several weeks to noticeably lower blood pressure. Be sure to keep taking the medicine, to give it time to work. Once it begins to work and symptoms improve, continue taking it as prescribed.

Do not stop taking this medicine without checking with the physician who prescribed it. Some conditions may get worse when patients stop taking calcium channel blockers abruptly. Check with the physician to find out how to gradually taper down before stopping the medicine completely.

Precautions

Seeing a physician regularly while taking calcium channel blockers is important. The physician will check to make sure the medicine is working as it should and will watch for unwanted side effects. People who have high blood pressure often feel perfectly fine. However, they should continue to see their physicians even when they feel well so that the physician can keep a close watch on their condition. They should also keep taking their medicine even when they feel fine.

Calcium channel blockers will not cure high blood pressure, but will help control the condition. To avoid the serious health problems that high blood pressure can cause, patients may have to take medicine for the rest of their lives. Furthermore, medicine alone may not be enough. People with high blood pressure may also need to avoid certain foods and keep their weight under control. The health care professional who is treating the condition can offer advice on what measures may be necessary. Patients being treated for high blood pressure should not change their diets without consulting their physicians.

Anyone taking calcium channel blockers for high blood pressure should not take any other prescription or over-the-counter medicine without first checking with his or her physician. Some medicines may increase blood pressure.

Some people feel drowsy or less alert than usual when taking calcium channel blockers. Anyone who takes these drugs should not drive, use machines, or do anything else that might be dangerous until they have found out how the drugs affect them.

People who usually have chest pain when they exercise or exert themselves may not have the pain when they are taking calcium channel blockers. This could lead them to be more active than they should be. Anyone taking this medicine should ask his or her physician how much exercise and activity is safe.

Some people get headaches that last for a short time after taking a dose of this medicine. This problem usually goes away during the course of treatment. If it does not, or if the headaches are severe, check with the physician who prescribed the medicine.

Patients taking certain calcium channel blockers may need to check their pulse regularly, as the drugs may slow the pulse too much. If the pulse is too slow, circulation problems may result. The physician who prescribed the medicine can show patients the correct way to check their pulse.

This medicine may cause the gums to swell, bleed, or become tender. If this problem occurs, check with a medical physician or dentist. To help prevent the problem, take care when brushing and flossing the teeth. Have regular dental check ups and cleanings.

Older people may be unusually sensitive to the effects of calcium channel blockers. This may increase the chance of side effects.

Special conditions

People with certain medical conditions or who are taking certain other medicines can have problems if they take calcium channel blockers. Before taking these drugs, be sure to let the physician know about any of these conditions:

Anyone who has had unusual reactions to calcium channel blockers in the past should let his or her physician know before taking the drugs again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

The effects of taking calcium channel blockers during pregnancy have not been studied in humans. However, in studies of laboratory animals, large doses of these drugs caused birth defects, stillbirth, and other problems when taken during pregnancy. Women who are pregnant or who may become pregnant should check with their physicians before using these drugs.

Some calcium channel blockers pass into breast milk, but there have been no reports of problems in nursing babies whose mothers were taking this medicine. However, women who need to take this medicine and want to breastfeed their babies should check with their physicians.

Calcium channel blockers may make heart or blood vessel disorders worse.

Effects of calcium channel blockers may be greater in people with kidney or liver disease, as their bodies are slower to clear the medicine from their systems.

Certain calcium channel blockers may also cause problems in people with a history of heart rhythm problems or with depression, Parkinson's disease, or other types of parkinsonism.

Before using calcium channel blockers, people with any of the medical problems listed here should make sure their physicians are aware of their conditions.

Taking calcium channel blockers with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

Side effects

Side effects are not common with this medicine, but some may occur. Minor discomforts, such as dizziness, lightheadedness, flushing, headache, and nausea, usually go away as the body adjusts to the drug and do not require medical treatment unless they persist or they are bothersome.

If any of the following side effects occur, check with the physician who prescribed the medicine as soon as possible:

• Breathing problems, coughing or wheezing
• Irregular, fast, or pounding heartbeat
• Slow heartbeat (less than 50 beats per minute)
• Skin rash
• Swollen ankles, feet, or lower legs.

Other side effects may occur. Anyone who has unusual symptoms after taking calcium channel blockers should get in touch with his or her physician.

Interactions

Calcium channel blockers may interact with a number of other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes calcium channel blockers should not take any other prescription or nonprescription (over-the-counter) medicines without first checking with his or her physician. Among the drugs that may interact with calcium channel blockers are:

• Diuretics (water pills). This medicine may cause low levels of potassium in the body, which may increase the chance of unwanted effects from some calcium channel blockers.
• Beta-blockers, such as atenolol (Tenormin), propranolol (Inderal), and metoprolol (Lopressor), used to treat high blood pressure, angina, and other conditions. Also, eye drop forms of beta blockers, such as timolol (Timoptic), used to treat glaucoma. Taking any of these drugs with calcium channel blockers may increase the effects of both types of medicine and may cause problems if either drug is stopped suddenly.
• Digitalis heart medicines. Taking these medicines with calcium channel blockers may increase the effects of the heart medicine.
• Medicines used to correct irregular heart rhythms, such as quinidine (Quinidex), disopyramide (Norpace), and procainamide (Procan, Pronestyl). Effects of these drugs may increase if used with calcium channel blockers.
• Anti-seizure medicines such as carbamazepine (Tegretol). Calcium channel drugs may increase the effects of these drugs.
• Cyclosporine (Sandimmune), a medicine that suppresses the immune system. Effects may increase if this medicine is taken with calcium channel blockers.

The list above does not include every drug that may interact with calcium channel blockers. Be sure to check with a physician or pharmacist before combining calcium channel blockers with any other prescription or nonprescription (over-the-counter) medicine.

Key Terms

Angina pectoris

A feeling of tightness, heaviness, or pain in the chest, caused by a lack of oxygen in the muscular wall of the heart.

Bipolar disorder

A severe mental illness in which a person has extreme mood swings, ranging from a highly excited state; sometimes with a false sense of well-being; to depression

Migraine

A throbbing headache that usually affects only one side of the head. Nausea, vomiting, increased sensitivity to light, and other symptoms often accompany migraine.

Further Reading

Gale Encyclopedia of Medicine. Gale Research, 1999.