Nifedipine

GENERIC NAME: nifedipine

DRUG CLASS AND MECHANISM
Nifedipine belongs to a class of medications called calcium channel blockers (CCBs) that are used to treat angina (heart pain), high blood pressure, and abnormal heart rhythms. Other drugs in the same class include amlodipine (Norvasc), diltiazem (Cardizem LA, Tiazac), felodipine (Plendil), isradipine (Dynacirc), nicardipine (Cardene), nimodipine (Nimotop), and verapamil (Covera-HS, Veralan PM, Calan). Like other CCBs, nifedipine works by blocking the flow of calcium into the muscle cells surrounding the arteries that supply blood to the heart (coronary arteries) as well as other arteries of the body. Since the inflow of calcium is what causes the muscle cells to contract, blocking the entry of calcium relaxes the muscles and dilates (widens) the arteries. By dilating coronary arteries, nifedipine increases the flow of blood to the heart. This treats and prevents angina which occurs when     the flow of blood to the heart is not adequate to supply the heart with enough oxygen necessary to pump blood. Relaxing the muscles surrounding other arteries of the body lowers blood pressure and thereby reduces the pressure against which the heart must pump blood and function. This reduces the demand of the heart for oxygen--another mechanism by which CCBs treat and prevent angina. In addition, nifedipine slows conduction of the electrical current that travels through the heart that causes the muscle of the heart to contract. This effect can be used to correct abnormally rapid heartbeats.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Capsules:10 and 20 mg. Tablets: 30, 60, and 90 mg

PRESCRIBED FOR
Nifedipine is used for the treatment and prevention of angina resulting from either an increased workload on the heart (as with exercise) or spasm of the coronary arteries. It is used in the treatment of high blood pressure, to treat abnormally fast heart rhythms such as atrial fibrillation, and in the prevention of episodes of rapid heart rhythm originating from the atria of the heart.

It also is used to dilate blood vessels that go into spasm such as those causing Raynaud's phenomenon, a painful condition of the hands caused by spasm of the arteries supplying blood to the hands. Non-FDA approved uses include anal fissures (applied to the fissures), prevention of migraine headaches in adults, ureteral stones (as secondary therapy) and wound healing (applied to the skin).

DOSING
The usual dose for nifedipine capsules is 10 to 20 mg three times daily. It is important to swallow capsules whole. For extended release tablets, the usual dose is 30 or 60 mg once daily. The tablets should be swallowed whole and not bitten or cut in half. Nifedipine can be taken with or without food.

DRUG INTERACTIONS
In rare instances, congestive heart failure has been associated with nifedipine, usually in patients already on a beta blocker, for example, propranolol (Inderal), metoprolol (Lopressor), etc. Excessive lowering of blood pressure (hypotension) during initiation of nifedipine treatment can occur, especially in patients already taking another blood pressure lowering drug.

Generally, nifedipine is avoided in children.

Nifedipine decreases the elimination of digoxin (Lanoxin) by the kidneys which can increase digoxin blood levels in the blood and give rise to digoxin toxicity. It is important, therefore, to monitor blood levels of digoxin in order to avoid toxicity.

Nifedipine interferes with the breakdown of tacrolimus (Prograf) by the liver, which in turn causes elevated blood levels of tacrolimus and may increase the risk of toxicity from tacrolimus.

Nifedipine reduces the blood levels of quinidine (Quinaglute, Quinidex, Quinora) which may reduce the effectiveness of quinidine. Conversely, blood levels of nifedipine are increased by quinidine and may lead to side effects from nifedipine.

Cimetidine (Tagamet) interferes with breakdown by the liver of nifedipine and increases nifedipine blood levels. Therefore, cautious dosing is necessary when both medications are administered concurrently.

Nifedipine should not be taken with grapefruit juice since grapefruit juice (one glass, approximately 200 ml) inhibits the breakdown of nifedipine by the liver and increases the levels of nifedipine in the blood.

USES
This medication is used to prevent certain types of chest pain (angina). It may allow you to exercise more and decrease the frequency of angina attacks. Nifedipine belongs to a class of medications known as calcium channel blockers. It works by relaxing blood vessels so blood can flow more easily. This medication must be taken regularly to be effective. It should not be used to treat attacks of chest pain when they occur. Use other medications (such as sublingual nitroglycerin) to relieve attacks of chest pain as directed by your doctor. Consult your doctor or pharmacist for details.OTHER This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.This medication may also be used to treat a certain blood circulation disorder (Raynaud's syndrome).

HOW TO USE
Take this medication by mouth, usually 3 times daily with or without food or as directed by your doctor. Swallow this medication whole. Do not crush, chew, or break the capsule.The dosage is based on your medical condition and response to treatment. Your doctor may gradually increase your dose. Follow your doctor's instructions carefully.Avoid eating grapefruit or drinking grapefruit juice while taking this medication unless your doctor instructs you otherwise. Grapefruit can increase the amount of certain medications in your bloodstream. Consult your doctor or pharmacist for more details.Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day.Tell your doctor if your condition worsens (for example, your chest pain worsens or is more frequent).

SIDE EFFECTS
Dizziness, flushing, weakness, swelling ankles/feet, and headache may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.To reduce dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor immediately if any of these unlikely but serious side effects occur: fast/irregular/pounding heartbeat, fainting.Tell your doctor immediately if any of these rare but very serious side effects occur: vision changes.A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS
Before taking this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies.This medication should not be used if you have a certain medical condition. Before using this medicine, consult your doctor or pharmacist if you have: a certain heart problem (aortic stenosis).Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver problems, kidney problems.Before having surgery, tell your doctor or dentist that you are taking this medication.This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.This medication passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS
See also the How to Use section.Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first.Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: phenytoin, quinidine, tacrolimus.Other medications can affect the removal of nifedipine from your body, which may affect how nifedipine works. Examples include cimetidine, azole antifungals (such as itraconazole), macrolide antibiotics (such as erythromycin), rifamycins (such as rifabutin), St. John's wort, drugs used to treat seizures (such as carbamazepine), among others.Check the labels on all your medicines (such as cough-and-cold products, diet aids) because they may contain ingredients that could increase your heart rate and worsen chest pain (including caffeine, pseudoephedrine, phenylephrine). Ask your pharmacist about using these products safely.Cimetidine is a nonprescription drug that is commonly used to treat extra stomach acid. Because cimetidine may interact with nifedipine, ask your pharmacist about other products to treat extra stomach acid.This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

OVERDOSE
If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US National Poison Hotline at 1-800-222-1222. Canada residents can call a provincial poison control center.

MISSED DOSE
If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE
Store at room temperature between 59-77 degrees F (15-25 degrees C) away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.MEDICAL ALERT: Your condition can cause complications in a medical emergency. For enrollment information call MedicAlert at 1-800-854-1166 (USA) or 1-800-668-1507 (Canada).