Published by Bupa's health information team, September 2009.
This factsheet is for people who are taking calcium-channel blockers or who would like information about them.
Calcium-channel blockers work on the muscle cells of the heart and arteries. They are medicines to treat high blood pressure and chest pain (angina). For more information about these conditions, see Related topics.
Your doctor may prescribe calcium-channel blockers if you have:
One type of calcium-channel blocker (verapamil) is sometimes used to prevent cluster headaches (severe headaches usually affecting the area around one eye or temple).
If you have angina, your doctor will normally only prescribe a calcium-channel blocker if beta-blockers (a different type of heart medicine) didn't work well enough on their own or there is a reason why you can't take them.
There are three main types of calcium-channel blockers.
Individual calcium-channel blockers work in different ways. So one that is taken to treat a certain condition may not be suitable for another.
Your heart is controlled by special cells that generate electrical impulses, acting like pacemakers. These impulses flow from cell to cell within the heart and are converted into chemical signals.
One of these chemical signals is a rising level of calcium inside a muscle cell. This causes the muscle to contract.
Calcium-channel blockers slow down the amount of calcium that can get into heart muscle cells and so reduce the amount of contraction.
The arteries that carry blood from your heart to the rest of your body have walls that contain a special type of muscle, called smooth muscle, which controls the width of the arteries.
As the level of calcium inside muscle cells increases, the muscle contracts and the artery narrows. This raises your blood pressure because your blood is squeezed into a smaller space.
When calcium channels are blocked, the muscle cells in the blood vessels relax, causing the arteries to widen (this is called vasodilation). This helps to lower blood pressure. Calcium-channel blockers also prevent angina by widening the arteries that supply the heart (coronary arteries).
Calcium-channel blockers are only available on prescription. They usually come as tablets or capsules that you take once or twice a day. Long-acting versions, which are sometimes called 'modified release', are also available.
You should make sure that you always have a prescription for the same brand of calcium-channel blocker as different brands can be absorbed into your body slightly differently.
Do not stop taking a calcium-channel blocker suddenly because this may make angina worse. Your doctor will tell you how to reduce your calcium-channel blockers gradually, if you need to stop taking them.
Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.
Your doctor may not prescribe calcium-channel blockers if you are pregnant or breastfeeding, if you have recently had a heart attack or have certain other conditions, or if you are taking beta-blockers. Talk to your doctor for more advice.
This section does not include every possible side-effect of calcium-channel blockers. Read the patient information leaflet that comes with your medicine for more information.
Calcium-channel blockers can cause a drop in your blood pressure. This can make you feel dizzy when you stand up. To prevent this, make sure you get up slowly when you stand up from a lying or sitting down position, and stay next to your chair or bed until you're sure that you are not feeling dizzy. You should not drive or do anything else that needs you to be alert until you know how you react to your medicine.
Calcium-channel blockers can also slow your heart down (especially the drugs called verapamil and diltiazem) and cause headaches, constipation, flushing and fluid retention.
Check with your doctor or pharmacist before you take any other medicines or herbal remedies at the same time as a calcium-channel blocker.
You should not eat grapefruit or drink grapefruit juice while taking some calcium-channel blockers, as this can affect how this medicine is absorbed by your body. Check with your doctor or your pharmacist.
The main types of calcium-channel blockers are shown in the table.
All medicines have a generic name. Many medicines also have one or more brand name. Generic names are written in lower case, whereas brand names start with a capital letter.
| Generic names | Examples of common brand names |
|---|---|
amlodipine |
Istin, Exforge (in combination with valsartan) |
diltiazem |
Tildiem, Adizem-SR, Adizem-XL, Angitil SR, Angitil XL, Calcicard CR, Dilcardia SR, Dilzem SR, Dilzem XL, Slozem, Tildiem LA, Tildiem Retard, Viazem XL, Zemtard |
felodipine |
Plendil |
isradipine |
Prescal |
lacidipine |
Motens |
lercanidipine |
Zanidip |
nicardipine |
Nicardipine, Cardene, Cardene SR |
nifedipine |
Adalat, Adalat LA, Adalat Retard, Adipine MR, Adipine XL, Coracten SR, Coracten XL, Fortipine LA 40, Hypolar Retard 20, Nifedipress MR, Tensipine MR, Valni XL |
nimodipine |
Nimotop |
verapamil |
Cordilox, Securon, Half Securon SR, Securon SR, Univer, Verapress MR, Vertab SR 240 |
See our answers to common questions about calcium-channel blockers, including:
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: September 2009
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