Cardioplen XL (Felodipine)

How does it work?

Cardioplen XL prolonged-release tablets contain the active ingredient felodipine, which is a type of medicine called a calcium channel blocker. This type of medicine acts on the heart and blood vessels. (NB. Felodipine is also available without a brand name, ie as the generic medicine.)

Felodipine works by slowing the movement of calcium through the muscle cells that are found in the walls of blood vessels. It does this by blocking 'calcium channels' in these muscle cells. Calcium is needed by muscle cells in order for them to contract, so by depriving them of calcium, felodipine causes the muscle cells to relax.

Felodipine acts specifically on the muscle cells in the walls of arteries, causing them to relax. This allows the arteries in the body to widen, an effect that has two main uses.

The relaxing and widening of the small arteries in the body decreases the resistance that the heart has to push against in order to pump the blood around the body. This reduces the pressure within the blood vessels. Felodipine can therefore be used to lower high blood pressure.

The widening effect on the small arteries in the heart also improves the blood and therefore oxygen supply to the heart. This feature means felodipine can be used in the management of angina. The chest pain of angina is caused by insufficient oxygen supply to the heart. As felodipine improves this oxygen supply, and also reduces the effort the heart has to make to pump blood, it is used to prevent angina attacks.

What is it used for?

  • High blood pressure (hypertension).
  • Angina (as a regular long-term treatment to prevent attacks).

How do I take it?

  • Cardioplen XL tablets are taken once a day, in the morning. The dose prescribed depends on the condition being treated and how well it is controlled. It is important to follow the instructions given by your doctor. These will be printed on the dispensing label your pharmacist has put on the packet of medicine.
  • Cardioplen XL tablets should be swallowed whole with a drink of water. They should not be broken, crushed or chewed.
  • The tablets can be taken either on an empty stomach or with a light meal. You should not take the tablets with a meal high in fat, as this can affect the rate of absorption of felopidine.
  • You should not drink grapefruit juice while you are taking this medicine, as it can increase the level of felodipine in your blood and thus increase the chance of getting side effects.


  • This medicine may cause fatigue and dizziness. You should take care when performing potentially hazardous activities, such as driving or operating machinery, until you know how this medicine affects you and are sure you can perform such activities safely.
  • If you experience any new chest pain after taking this medicine, or you think your angina is getting worse, you should not take a further dose until you have consulted your doctor.
  • This medicine should not be used to treat an attack of angina, as it won't work quickly enough.

Use with caution in

  • Elderly people.
  • Decreased liver function.
  • People with a serious defect in the heart's electrical message pathways, resulting in decreased function of the heart (2nd or 3rd degree heart block).
  • People with a history of heart failure or a weak heart (especially left ventricular failure).
  • People with a very fast heart rate (tachycardia).
  • Hereditary blood disorders called porphyrias.

Not to be used in

  • Allergy to other related calcium channel blockers (dihydropyridines), eg nifedipine, amlodipine.
  • Angina that is increasing in severity, duration or frequency and is not well controlled by medical treatment (unstable angina).
  • People with a condition called aortic stenosis, which is narrowing of the main artery from the heart through which blood is pumped to the rest of the body.
  • People who are having a heart attack or who have had a heart attack in the last month.
  • Failure of the heart to maintain adequate circulation of blood (cardiogenic shock).
  • Uncontrolled heart failure.
  • Pregnancy.
  • This medicine is not recommended for children.

This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • The safety of this medicine in pregnancy has not been established. It should not be taken by women who are pregnant, and women who could get pregnant should use an effective method of contraception to prevent pregnancy while taking this medicine. Seek further medical advice from your doctor.
  • This medicine may pass into breast milk in small amounts. As there is no information available about the effect of this medicine on newborn babies, it is recommended that this medicine is not used by breastfeeding mothers. Seek further medical advice from your doctor.

Label warnings

  • This medication is to be swallowed whole, not chewed.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

The following side effects may occur particularly at the start of treatment, when the dose is increased or when high doses are administered - they usually improve after a few days.

  • Flushing.
  • Headache.
  • Awareness of your heart beat (palpitations).
  • Dizziness.
  • Fatigue.
  • Ringing or other noise in the ears (tinnitus).

Other side effects reported with felodipine include:

  • Excessive fluid retention in the body tissues, resulting in swelling of ankles (oedema).
  • Worsening of angina chest pains (see warning section above).
  • Mild swelling of the gums (gingival hyperplasia). This can be avoided with careful dental hygiene; ask your doctor or dentist for advice.
  • Rash or itching.
  • Erectile dysfunction (impotence).
  • Fever.
  • Increased need to pass urine.
  • Faster than normal heart beat (tachycardia).
  • Fainting.
  • Pins and needles sensations.
  • Disturbances of the gut, such as nausea, vomiting, diarrhoea, constipation.
  • Low blood pressure.
  • Pain in the muscles or joints.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

Felodipine may have an additive effect with other medicines that decrease blood pressure, particularly other medicines used to treat high blood pressure (antihypertensives). If the combination of medicines lowers your blood pressure too much this could make you feel dizzy. If this happens to you, you should sit or lie down until the symptoms pass. If you frequently feel dizzy when taking felodipine in combination with other medicines that can lower blood pressure you should let your doctor know, as your doses may need adjusting. Other medicines that can decrease blood pressure include the following:

  • ACE inhibitors, eg enalapril
  • aldesleukin
  • alpha-blockers such as prazosin
  • alprostadil
  • angiotensin II receptor antagonists such as losartan
  • antipsychotics
  • benzodiazepines, eg temazepam, diazepam
  • baclofen
  • beta-blockers such as propranolol
  • other calcium-channel blockers, eg verapamil, nifedipine
  • clonidine
  • diazoxide
  • diuretics, eg furosemide, bendroflumethiazide
  • dopamine agonists, eg bromocriptine, apomorphine
  • hydralazine
  • levodopa
  • MAOI antidepressants, eg phenelzine
  • methyldopa
  • minoxidil
  • moxisylyte
  • moxonidine
  • nicorandil
  • nitrates, eg glyceryl trinitrate
  • tizanidine.

The following medicines may increase the breakdown of felodipine by the liver, which could make it less effective:

  • carbamazapine
  • phenobarbital
  • phenytoin
  • primidone
  • rifampicin
  • the herbal remedy St John's wort (Hypericum perforatum).

The following medicines may decrease the breakdown of felodipine by the liver, which could increase the risk of its side effects:

  • cimetidine
  • clarithromycin
  • erythromycin
  • itraconazole
  • ketoconazole
  • protease inhibitors for HIV infection, eg ritonavir, nelfinavir, saquinavir
  • telithromycin.

Felodipine may increase the blood level of the immunosuppressant medicine tacrolimus. If you are taking this medicine in combination with tacrolimus the level of tacrolimus in your blood should be monitored.

Felodipine may cause a small increase in the blood level of digoxin. This is not normally significant, but you should let your doctor know if you think you are experiencing any digoxin-related side effects after starting treatment with this medicine.

The following medicines may reduce the blood pressure lowering effect of this medicine:

  • corticosteroids, such as dexamethasone or prednisolone
  • oestrogens, such as those in the contraceptive pill
  • regular use of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, diclofenac or indomethacin (occasional painkilling doses are unlikely to have a significant effect).

Other medicines containing the same active ingredient

CabrenFelendil XL Felogen XL
Felotens XL Neofel XL Parmid XL

Felodipine modified-release tablets are also available without a brand name, ie as the generic medicine.