Calcium channel blockers – By Dr.Harold Gunatillake

Calcium channel blockers
By Dr.Harold Gunatillake FRCS, FIACS, FICS, AM (Sing), MBBS. – Health writer

Do you know what calcium channel blockers are?
Most of you may be on a calcium channel blocker, prescribed by your
family physician, without your knowledge, for High Blood Pressure (essential
hypertension).

They are also called calcium antagonists, given for the treatment of a variety of conditions, such as high blood pressure, migraine and Raynaud’s disease (peripheral arterial spasm).

Calcium is required by the heart muscles and other blood vessels for efficient contraction movement. So blocking such a mechanism or inhibiting transport of calcium into cells will lower the blood pressure and widen blood vessels by affecting the muscle cells in the arterial walls, especially those of the coronary arteries. These calcium antagonists also tend to slow the heart rate which is also beneficial in situations where not only the blood pressure but also the heart rate needs to be slowed down for efficient muscle contractions and prevent premature aging of the muscle cells of the heart. By such action, the blood pressure is lowered chest pain (angina) is relieved and also corrects irregular heartbeat.

Some calcium channel blockers are available in short-acting forms and other long-acting forms. The quick-acting ones act quickly and the effects last only a few hours, while the long-acting medications are slowly released to provide a longer-lasting effect.

Examples of calcium channel blocking medication available include:
• Amlodipine (Norvasc)
• Diltiazem (Cardizem)
• Felodipine (Plendil)
• Isradipine (DynaCirc SR)
• Nifedipine (Adalat CC)
• Nisoldipine (Sular)
• Verapamil ( Calan Verelan

These drugs are normally prescribed in combination with other antihypertensive drugs. These calcium channel blockers are beneficial to prevent or improve symptoms in a variety of conditions, including
• High blood pressure
• Chest pain due to angina
• Migraine headaches
• Brain aneurysm complications
• Irregular heart beats
• Circulatory conditions like Raynaud’s disease

Effect on kidneys
Studies suggest that calcium channel blockers do not worsen the progression of renal disease but may rather provide benefit when systemic blood pressure has been tightly normalized.

Side effects of these medications are:
• Constipation-(beware of verapamil). Increase your fiber content and
drink plenty of water)
• Headache-(due to widening of arteries)
• Rapid heart rate
• Rash
• Drowsiness
• Flushing- (due to widening and relaxing of arteries)
• Nausea
• Swelling of legs and feet (pitting edema due to water retention).
Serious side effects are rare, and it is not wise to stop calcium-channel blockers without speaking to your doctor.

Most people who take these medications have no side –effects, or only
minor ones.

These channel blockers should not be taken with grapefruit as they can reduce your liver’s ability to eliminate calcium channel blockers from your body, allowing the medications to build up in your body.

Rebound effect
Some people who suddenly stop taking a calcium-channel blocker have a ‘rebound’ flare up of angina. Therefore, it is best not to stop taking these drugs without first consulting a doctor.

Check your blood pressure weekly until it is stable. Early high blood pressure has no early signs or symptoms as the body gets accustomed to the slow rising of the blood pressure. Most heart attacks and stroke are preventable if your blood pressure is taken care of.

Hope this article will be useful.
Stay safe