BMA Concise Guide to Medicine & Drugs

Nifedipine

Brand names Adalat, Adipine, Coracten, Fortipine LA, Hyolar Retard 20, Nifedipress MR, Tensipine MR, Valni, and others

Used in the following combined preparations Beta-Adalat, Tenif

QUICK REFERENCE

Drug group Anti-angina drug and antihypertensive drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Nifedipine belongs to a group of drugs known as calcium channel blockers (see Anti-angina drugs), which interfere with conduction of signals in the muscles of the heart and blood vessel walls.

Nifedipine is given as a regular medication to help prevent angina attacks but is not used to treat acute attacks. The drug can be used safely by asthmatics, unlike some other anti-angina drugs (such as beta blockers).

Nifedipine is also widely used to reduce high blood pressure and is often helpful in improving circulation to the limbs in disorders such as Raynaud’s disease.

Like other drugs of its class, it may cause blood pressure to fall too low, and occasionally causes disturbances of heart rhythm. In rare cases, angina worsens as a result of taking nifedipine, and another drug must be substituted.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, capsules, SR tablets, SR capsules.

Frequency and timing of doses 3 x daily; 1–2 x daily (SR preparations).

Adult dosage range 15–90mg daily.

Onset of effect 30–60 minutes.

Duration of action 6–24 hours.

Diet advice Nifedipine should not be taken with grapefruit juice.

Storage Keep in original container at room temperature out of the reach of children. Protect from light.

Missed dose Take as soon as you remember, or when needed. If your next dose is due within 3 hours, take a single dose now and skip the next.

Stopping the drug Do not stop taking the drug without consulting your doctor; sudden withdrawal may make angina worse.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may cause dizziness. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

Nifedipine can cause a variety of minor adverse effects. Common side effects include headache; dizziness, especially on rising, which may be due to reduced blood pressure; flushing; ankle swelling; and palpitations. More rarely, there may be frequency in passing urine and a rash. If any of these effects are severe, discuss with your doctor. Patients with angina may notice an increase in the severity or frequency of attacks. If so, the drug should be stopped and medical advice should be sought immediately; it may be necessary to adjust the dosage or change to a different drug.

INTERACTIONS

General note Nifedipine may interfere with the beneficial effects of drugs such as carbamazepine, ciclosporin, magnesium (by injection), tacrolimus, and theophylline. Consult your doctor or pharmacist.

Antihypertensive drugs Nifedipine may increase the effects of these drugs.

Phenytoin and rifampicin These drugs may reduce the effects of nifedipine.

Digoxin Nifedipine may increase the effects and toxicity of digoxin.

Grapefruit juice may block breakdown of nifedipine, increasing its effects.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have liver or kidney problem.

· You have heart failure.

· You have had a recent heart attack.

· You have aortic stenosis.

· You have diabetes.

· You have porphyria.

· You are taking other medicines.

Pregnancy May inhibit labour but the small risk to the baby has to be weighed against the risk to the mother of uncontrolled hypertension. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk but only in amounts that are probably too small to harm your baby. Discuss with your doctor.

Infants and children Not recommended.

Over 60 Increased likelihood of adverse effects. Reduced dose may therefore be necessary.

Driving and hazardous work Avoid such activities until you have learned how nifedipine affects you because the drug can cause dizziness as a result of lowered blood pressure.

Alcohol Avoid. Alcohol may increase the blood-pressure-lowering effects of nifedipine.

Surgery and general anaesthetics Nifedipine may interact with some general anaesthetics causing a fall in blood pressure. Discuss this with your doctor or dentist before any surgery.

PROLONGED USE

No problems expected.