• Nifedipine may be used to treat angina.
• Nifedipine works by inhibiting the influx of calcium ions across cardiac (heart) and smooth muscle causing relaxation of these muscles and dilation (widening). The exact way nifedipine works in angina is not known; however, experts believe it helps prevent spasm of the coronary artery and reduces how hard the heart has to work to pump blood around the body, lowering its oxygen requirements. Nifedipine does not change levels of calcium in the blood.
• Nifedipine belongs to a class of medicines called calcium channel blockers (sometimes called calcium channel antagonists).

• Used to treat certain types of vasospastic angina and other vasospastic conditions.
• Also used in the treatment of chronic stable angina in patients intolerant of, or not adequately controlled by, beta-blockers or nitrates.
• Has a quick onset of effect.
• Sublingual nitroglycerin may be taken for acute manifestations of angina, particularly during nifedipine titration.
• Although no "rebound" effect has been seen on discontinuation of nifedipine, it is suggested that the dose be withdrawn gradually under a doctor's supervision.
• Generic nifedipine is available.

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Dizziness, light-headedness, flushing, headache, weakness, nausea, heartburn, and muscle cramps or tremor. Nervousness, palpitations, cough, and nasal congestion may also be reported.
• Excessive and poorly tolerated hypotension (low blood pressure) is experienced by some people. The risk is greater during initial therapy or upwards dose titration and may be more common in those already taking beta-blockers. Nifedipine capsules should not be used to reduce blood pressure quickly as this may be fatal.
• The dosage of nifedipine must be established by slow titration as excessive dosages can result in hypotension, preferably over a 7 to 14 day period. Dosages of greater than 120mg/day are rarely necessary and more than 180 mg/day is not recommended.
• Peripheral edema (fluid retention in the lower limbs) occurs in one in ten people prescribed nifedipine. Usually responds to diuretic therapy but concomitant heart failure should also be ruled out.
• Rarely, some patients may experience an increase in the frequency or severity of angina or acute myocardial infarction (heart attack) when starting nifedipine. The risk is greater in those with severe obstructive coronary artery disease.
• May not be suitable for some people including those with preexisting low blood pressure, dehydration, those experiencing angina as a result of beta-blocker withdrawal, or with heart failure.
• May interact with grapefruit juice and grapefruit products and several drugs including beta-blockers, digoxin, cimetidine, fentanyl, and phenytoin. See prescribing information for a full list of drug interactions.
• Animal studies report that nifedipine causes birth defects in rats and rabbits. There have been no controlled studies in humans.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

• May be taken with or without food. Take exactly as directed by your doctor.
• Do not take nifedipine with any grapefruit juice or other products made using grapefruit (such as marmalade).
• Your blood pressure may need to be carefully monitored during the initial administration and titration of nifedipine. Tell your doctor if you feel dizzy, particularly when going from a sitting or lying down position to standing. Dizziness may increase your risk of falls.
• May alter the results of some laboratory tests and increase bleeding time. Tell other health professionals that you are taking nifedipine.
• Do not stop taking nifedipine suddenly. Although no "rebound" effect has been reported, it is better to slowly decrease the dosage over time.
• Your doctor may advise you to take sublingual nitroglycerin during the initial administration of nifedipine. Follow his/her advice.
• Talk to your doctor if you develop edema, angina pain, are pregnant or become pregnant, or develop any other worrying side effects.

• Nifedipine is quickly absorbed when taken orally and peak blood levels occur in approximately 30 minutes. It is relatively short-acting and needs to be taken three times a day.

Medicines that interact with nifedipine may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with nifedipine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with nifedipine include:

• anticonvulsants, such as carbamazepine, divalproex, or fosphenytoin
• antifungal agents, such as itraconazole or ketoconazole
• anti-inflammatory medications such as adalimumab
• antipsychotics, such as aripiprazole
• antivirals such as atazanavir, darunavir, delavirdine
• alfentanil
• amiodarone
• baclofen
• beta-blockers, such as atenolol, bisoprolol, labetalol, or metoprolol (may increase the risk of congestive heart failure, severely low blood pressure, or angina exacerbations)
• bupropion
• buspirone
• calcium-containing medications
• cancer medications
• cimetidine
• cisapride
• clonidine
• corticosteroids, such as budesonide or dexamethasone
• cyclosporine
• digoxin (may elevate digoxin levels)
• ginseng
• ginkgo
• levodopa
• metformin
• rifampin
• medications that reduce high cholesterol, such as atorvastatin, lovastatin or simvastatin
• nitroglycerin
• NSAIDs, such as diclofenac, ibuprofen, and indomethacin, may decrease the blood pressure-lowering capabilities of nifedipine
• other heart medications, such as diltiazem, or flecainide
• opioids, such as alfentanil, buprenorphine, or codeine
• pimozide
• quinidine
• St John's wort
• tacrolimus
• warfarin and other coumarin anticoagulants.

Nifedipine should not be administered with grapefruit juice or grapefruit products because this results in an approximately 2-fold increase in nifedipine levels.

Note that this list is not all-inclusive and includes only common medications that may interact with nifedipine. You should refer to the prescribing information for nifedipine for a complete list of interactions.