Calcium-channel blockers Q&As
Published by Bupa's health information team, September 2009.
Answers to questions about calcium-channel blockers
This section contains answers to common questions about this topic. Questions have been suggested by health professionals, website feedback and requests via email.
- What is the different between XL and SR forms of a drug?
- I have forgotten to take a tablet - what should I do?
- Can I carry on taking my calcium-channel blocker if I become pregnant?
What is the difference between XL and SR forms of a drug?
XL forms of calcium-channel blockers last for longer than SR forms. This means you need to take them less often.
Explanation
Some types of tablets or capsules are designed specifically to be broken down slowly in your body, so that the medicine takes longer to get into your bloodstream. This means your body receives a steady, continuous dose of the medicine, and its effects last for longer than those of an ordinary tablet. Different forms may release the active medicine into your bloodstream at different rates.
These medicines may have letters after their brand name to show that they are slow-release forms, such as SR, MR, CR, XL or LA, or the term Retard. Diltiazem and nifedipine are examples of calcium-channel blockers that have a number of different slow-release forms.
SR means sustained release. These tablets/capsules have been modified to release the medicine over a few hours, for example, the medicine might be in granule form rather than powder form. They are usually taken twice daily. Different brands of medicine may use the terms MR (modified release), CR (controlled release) or Retard.
XL means extended release. These medicines are designed to stay in your body even longer - usually over 24 hours. This means you may only have to take your medicine once a day. Different brands of medicine may use the term LA (long-acting) instead of XL.
These slow-release medicines should be swallowed whole and not chewed, crushed or broken up, as this makes their slow-release mechanism ineffective. It can be dangerous if all the medicine is released into your body at once.
You should not use a different brand from the one that has been prescribed for you, as different brands can be released into your body at a slightly different rate.
Sources
- Adizem-SR. Electronic medicines compendium. www.emc.medicines.org.uk, accessed 30 May 2009
- Joint Formulary Committee. British National Formulary. 57th ed. London: British Medical Association and the Royal Pharmaceutical Society of Great Britain, 2009:113-118
I have forgotten to take a tablet - what should I do?
This depends on the exact type of calcium-channel blocker you are taking, and how late you are with taking your medicine.
Explanation
You should check the patient information leaflet in the medicine packet to find out what you need to do if you miss a dose of your medicine. Usually, you will just need to take your medicine as soon as you remember it. But if it's nearly time for your next dose, you should miss a dose, and just take the next dose at the normal time. Never take a double dose to make up for one that you have forgotten, as it can be dangerous to have a high level of the medicine in your body.
With some medicines, you shouldn't take the missed tablet/capsule if your next dose is due within the next eight hours or the next 12 hours. All medicines are different, so it's important that you check the patient information leaflet.
You should never stop taking your calcium-channel blockers unless your doctor tells you to. Calcium-channel blockers need to be stopped gradually because stopping them suddenly can cause pain and tightness in your chest.
Sources
- Electronic medicines compendium. www.emc.medicines.org.uk, accessed 30 May 2009
- Joint Formulary Committee. British National Formulary. 57th ed. London: British Medical Association and the Royal Pharmaceutical Society of Great Britain, 2009:113
Can I carry on taking my calcium-channel blocker if I become pregnant?
You may need to stop taking your calcium-channel blocker if you become pregnant. However, talk to your GP before stopping any medicines - he or she will tell you if you need to change your medicine.
Explanation
Some calcium-channel blockers are not advised for women who are pregnant. You should tell your GP if you are trying for a baby or have become pregnant.
Diltiazem can be harmful to your unborn baby. It shouldn't be taken while you are pregnant or if you're trying for a baby. Your doctor might prescribe a difference medicine instead. Other calcium-channel blockers, such as nifedipine and verapamil, are also thought to be best avoided while pregnant, but you may need to keep taking them for your own health. If you are taking these medicines, your GP will weigh up the risk of harm to your baby against your need for the medicine.
If you usually take calcium-channel blockers for high blood pressure and want to try for a baby or become pregnant, your GP may suggest switching you to a different type of medicine, such as a beta-blocker or a medicine called methyldopa.
You may also need to carry on taking alternative medicines to calcium-channel blockers while you are breastfeeding, as the medicines can get into your breast milk.
Sources
- Electronic medicines compendium. www.emc.medicines.org.uk, accessed 29 May 2009
- Joint Formulary Committee, British National Formulary. 57th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 2009; 113-118
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
Calcium-channel blockers factsheet
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