Adalat LA (nifedipine)

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How does it work?

Adalat LA tablets contain the active ingredient nifedipine, which is a type of medicine called a calcium channel blocker. This type of medicine acts on the heart and blood vessels.

Nifedipine 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, nifedipine causes the muscle cells to relax.

Nifedipine 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. Nifedipine can therefore be used to lower high blood pressure.

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

Adalat LA tablets are a 'long-acting' or 'modified-release' form of nifedipine. This means that they are designed to release the nifedipine slowly and continuously over 24 hours, producing a steady blood level of the medicine throughout the day. The tablets are designed to be taken once a day, at the same time each day (preferably in the morning). They must be swallowed whole with water and not broken, chewed or crushed, as this would damage the modified-release action.

What is it used for?

- High blood pressure
- Prevention of angina attacks.

Warning!

- Blood pressure lowering medicines can occasionally make you feel dizzy or weary. If you are affected, you should take care when driving or operating machinery.
- You should not drink grapefruit juice while you are taking this medicine, as it can increase the level of the medicine in your blood and thus increase its effect on your blood pressure. This could make you feel dizzy. If you have been regularly drinking grapefruit juice, this effect can last for at least three days after your last drink.
- If you experience any chest pain after taking this medicine you should not take a further dose until you have consulted your doctor.
- This medicine must not be used to treat an attack of angina.
- There are several different brands of long-acting or slow-release nifedipine available in the UK (see end of factsheet).

These can usually be identified because their names end in XL, MR, LA, SR and so on. The way that the nifedipine is released from different brands can vary and this means that different brands can have different clinical effects. For this reason, it is important that you always take the same brand of nifedipine. You should make sure you know which brand you take and check that you have been given the correct one each time your medicine is dispensed. (Your pharmacist will usually ask you, or call your doctor if this is not written on your prescription).
- The outer membrane of Adalat LA tablets will pass through your gut without being digested and may be visible in your stools. This is normal.

Use with caution in

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- Elderly people
- People having kidney dialysis
- Heart failure
- Poor functioning of one chamber of the heart (left ventricular dysfunction)
- Very low blood pressure (hypotension)
- Diabetes.

Not to be used in

- Decreased liver function
- History of any narrowing or blockage in the foodpipe, stomach or intestines
- Inflammatory bowel disease such as ulcerative colitis or Crohn's disease
- People who have had a surgical procedure called an ileostomy (where the small intestine is attached to the abdominal wall to a bag outside the body), after surgical removal of the rectum and part or all of the colon (proctocolectomy)
- Allergy to related calcium channel blockers (dihydropyridines), eg amlodipine, felodipine, nicardipine
- Angina not well controlled by medical treatment
- Narrowing of the main artery coming from the heart (aortic stenosis)
- Failure of the heart to maintain adequate circulation of blood (cardiogenic shock)
- People who have had a heart attack in the last month
- Hereditary blood disorders called porphyrias.
- This medicine is not recommended for children.

This medicine should not be used if you are allergic to one or 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.

- This medicine should not normally be used during pregnancy as its safety has not been established. However, it is occasionally used to control high blood pressure in pregnant women, in which case any possible risk to the foetus from the medicine needs to be weighed against the possible risk of uncontrolled high blood pressure in the mother.

Seek medical advice from your doctor.
- This medicine passes into breast milk in amounts that are probably too small to be harmful to the nursing infant. However, since the medicine does pass into breast milk, the manufacturer recommends that it should not used by breastfeeding mothers. Seek medical advice from your doctor.

Label warnings

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

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