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Quinidine sulfate

Pronunciation

Generic Name: quinidine sulfate (KWIN-ih-deen)
Brand Name: Generic only. No brands available.

Quinidine sulfate is associated with an increased risk of death when used to treat non-life-threatening irregular heartbeat. This risk may be greater if you have structural heart disease. Talk with your doctor for more information.


Quinidine sulfate is used for:

Treating and preventing certain abnormal heart rhythms.

Quinidine sulfate is an antiarrhythmic. It works by stabilizing the heart rhythm in conditions in which the heart is beating too fast or in an irregular rhythm (antiarrhythmic effect).

Do NOT use quinidine sulfate if:

  • you are allergic to any ingredient in quinidine sulfate
  • you have certain severe, uncontrolled, abnormal heart rhythms; muscle weakness due to myasthenia gravis; or you have previously developed unusual bruising while using quinidine sulfate or similar medicines
  • you are taking astemizole, codeine, cisapride, a class III antiarrhythmic medicine (eg, amiodarone), terfenadine, itraconazole, a ketolide antibiotic (eg, telithromycin), a macrolide antibiotic (eg, erythromycin), a nondepolarizing muscle relaxant (eg, pancuronium), a phenothiazine (eg, chlorpromazine), a phosphodiesterase type 5 inhibitor (eg, sildenafil), pimozide, a quinolone antibiotic (eg, ciprofloxacin), succinylcholine, terfenadine, or voriconazole

Contact your doctor or health care provider right away if any of these apply to you.

Before using quinidine sulfate:

Some medical conditions may interact with quinidine sulfate. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have a history of liver or kidney disease; congestive heart failure, heart block, QT prolongation, or other heart problems; low blood pressure; high or low blood calcium levels; decreased blood platelets; or digitalis intoxication

Some MEDICINES MAY INTERACT with quinidine sulfate. Tell your health care provider if you are taking any other medicines, especially any of the following:

  • Barbiturates (eg, phenobarbital), hydantoins (eg, phenytoin), nifedipine, or rifampin because the effectiveness of quinidine sulfate may be decreased
  • Amiloride, amiodarone, carbonic anhydrase inhibitors (eg, acetazolamide), cimetidine, itraconazole, ketoconazole, thiazide diuretics (eg, hydrochlorothiazide), verapamil, or voriconazole because side effects, such as increased risk of low blood pressure or heart conduction disturbances and racing heart rate, dizziness, or fainting, may occur
  • Arsenic, astemizole, cisapride, class III antiarrhythmics (eg, amiodarone), dofetilide, droperidol, haloperidol, HIV protease inhibitors (eg, indinavir), ketolide antibiotics (eg, telithromycin), macrolide antibiotics (eg, erythromycin), phenothiazines (eg, chlorpromazine), phosphodiesterase type 5 inhibitors (eg, sildenafil), pimozide, quinolones, streptogramins (eg, pristinamycin), terfenadine, or ziprasidone because the actions and side effects of quinidine sulfate and these medicines may be increased
  • Anticoagulants (eg, warfarin), aripiprazole, beta-adrenergic blockers (eg, metoprolol), digitoxin, digoxin, nondepolarizing muscle relaxants (eg, pancuronium), norepinephrine reuptake inhibitors (eg, atomoxetine), procainamide, propafenone, or succinylcholine because the actions or side effects of these medicines may be increased
  • Anticholinesterases (eg, pyridostigmine) or narcotic analgesics (eg, codeine) because the effectiveness of these medicines may be decreased

This may not be a complete list of all interactions that may occur. Ask your health care provider if quinidine sulfate may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use quinidine sulfate:

Use quinidine sulfate as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • It is best to take quinidine sulfate on an empty stomach at least 1 hour before or 2 hours after eating. If stomach upset occurs, you may take it with food to reduce stomach irritation.
  • Take quinidine sulfate with a full glass of water (8 oz/240 mL). Do not lie down for 30 minutes after taking quinidine sulfate.
  • Take quinidine sulfate regularly to receive the most benefit from it.
  • Continue to use quinidine sulfate even if you feel well. Do not miss any doses.
  • Eating grapefruit or drinking grapefruit juice may affect the amount of quinidine sulfate in your blood. Talk with your doctor before including grapefruit or grapefruit juice in your diet.
  • If you miss a dose of quinidine sulfate, take it as soon as possible. If it is almost time for our next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use quinidine sulfate.

Important safety information:

  • Quinidine sulfate may cause dizziness or blurred vision. Do not drive, operate machinery, or do anything else that could be dangerous until you know how you react to quinidine sulfate.
  • Quinidine sulfate may cause increased sensitivity to the sun. Avoid exposure to the sun, sunlamps, or tanning booths until you know how you react to quinidine sulfate. Use a sunscreen or protective clothing if you must be outside for a prolonged period.
  • Do not suddenly stop taking quinidine sulfate without checking with your doctor.
  • Before you have any medical or dental treatments, emergency care, or surgery, tell the doctor or dentist that you are using quinidine sulfate.
  • LAB TESTS, including heart function tests, may be performed to monitor your progress or to check for side effects. Be sure to keep all doctor and lab appointments.
  • Use quinidine sulfate with extreme caution in CHILDREN. Safety and effectiveness have not been confirmed.
  • PREGNANCY and BREAST-FEEDING: If you become pregnant, discuss with your doctor the benefits and risks of using quinidine sulfate during pregnancy. Quinidine sulfate is excreted in breast milk. Do not breast-feed while you are taking quinidine sulfate.

Possible side effects of quinidine sulfate:

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Blurred vision; diarrhea; heartburn; nausea; stomach discomfort; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); dark urine; dizziness or lightheadedness; fainting; fast, slow, or irregular heartbeat; headache; hearing changes or loss of hearing; mood or mental changes; pale stools; ringing in ears; severe or persistent stomach pain; vision changes; yellowing of the skin or eyes.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

If OVERDOSE is suspected:

Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include diarrhea; disturbed vision; fainting; fast or slow heartbeat; low blood pressure; ringing in the ears; trouble breathing; trouble walking.

Proper storage of quinidine sulfate:

Store quinidine sulfate between 59 and 86 degrees F (15 and 30 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep quinidine sulfate out of the reach of children and away from pets.

General information:

  • If you have any questions about quinidine sulfate, please talk with your doctor, pharmacist, or other health care provider.
  • Quinidine sulfate is to be used only by the patient for whom it is prescribed. Do not share it with other people.
  • If your symptoms do not improve or if they become worse, check with your doctor.
  • Check with your pharmacist about how to dispose of unused medicine.

This information should not be used to decide whether or not to take quinidine sulfate or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about quinidine sulfate. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to quinidine sulfate. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using quinidine sulfate.

Issue Date: April 2, 2014
Database Edition 14.2.1.001
Copyright © 2014 Wolters Kluwer Health, Inc.

Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.

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