Quinidine

By

Generic Name: Quinidine Brand Name(s): Generics only. No brands available.

Uses

What is Quinidine used for?

Quinidine is used to treat or prevent many types of irregular heartbeats (heart arrhythmias such as atrial fibrillation). Quinidine can greatly improve your ability to perform normal activities by decreasing the number of irregular heartbeats you have. However, it may not stop all your irregular heartbeats completely. It works by blocking abnormal heartbeat signals.

Before and while you are using quinidine, your doctor may prescribe other medications (e.g., “blood thinners”/anticoagulants such as warfarin, beta blockers such as metoprolol) to shrink any blood clots in the heart and to slow your pulse.

How should I take Quinidine?

Take this medication by mouth with or without food with a full glass of liquid (8 ounces/240 milliliters) as directed by your doctor. This medication is best taken on an empty stomach, but taking it with food may help decrease stomach upset. Do not lie down for 10 minutes after taking this medication.

Do not crush or chew extended-release tablets. Doing so can release all of the drug at once, increasing the risk of side effects. Also, do not split the tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing.

There are different brands and forms of this medication available. Not all have identical effects. Do not change quinidine products without talking to your doctor or pharmacist.

Dosage is based on your medical condition and response to treatment. If you are taking regular-release quinidine for an irregular heartbeat, the manufacturer recommends that you take no more than 4 grams daily.

Avoid eating grapefruit or drinking grapefruit juice while being treated with this medication unless your doctor instructs you otherwise. Grapefruit juice can change the amount of certain medications in your bloodstream. Consult your doctor or pharmacist for more details.

Avoid large changes in your dietary salt intake while being treated with this medication unless your doctor instructs you otherwise. The amount of salt in your diet may affect the amount of quinidine absorbed by your system. 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 time(s) each day.

Tell your doctor if your condition does not improve or if it worsens.

How do I store Quinidine?

Quinidine is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Quinidine in the bathroom or the freezer. There may be different brands of Quinidine that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Quinidine down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Quinidine?

Before taking quinidine, tell your doctor or pharmacist if you are allergic to it; or to quinine; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: certain types of heart disease (e.g., incomplete or complete heart block without an artificial pacemaker, torsades-type irregular heartbeats, digitalis toxicity), very low blood pressure, history of easy bruising/bleeding (thrombocytopenic purpura) with use of quinine or quinidine, severe muscle weakness (myasthenia gravis), kidney disease, liver disease, a certain blood disorder (G6PD deficiency), asthma, current infection with fever.

Quinidine may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that require immediate medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using quinidine, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/”water pills”) or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using quinidine safely.

This drug may make you dizzy. Alcohol or marijuana can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana.

Before having surgery, tell your doctor that you are using this medication.

Older adults may be more sensitive to the side effects of this drug, especially dizziness and QT prolongation.

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.

Is it safe during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this Quinidine during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Quinidine. Quinidine is pregnancy risk category C according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown

Side effects

What side effects can occur from Quinidine?

Diarrhea, nausea, vomiting, loss of appetite, stomach pain/cramps, or a burning feeling in throat or chest (e.g., heartburn) may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

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 right away if you have any serious side effects, including: vision changes, eye pain, muscle pain, unusual sweating or shakiness (signs of low blood sugar), unexplained fever/signs of infection (e.g., persistent sore throat), easy bruising/bleeding, extreme tiredness, dark urine, persistent nausea/vomiting, yellowing eyes/skin, lupus-like symptoms (joint/muscle pain, chest pain).

Get medical help right away if you have any very serious side effects, including: severe dizziness, fainting, sudden change in heartbeat (faster/slower/more irregular).

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

One type of reaction (cinchonism) can occur after even a single dose of this drug. Contact your doctor of pharmacist promptly if you notice symptoms such as ringing in the ears, sudden hearing problems, headache, blurred vision, confusion. Your dosage may need to be adjusted.

Certain long-acting brands of quinidine may appear as a whole tablet in the stool. This is the empty shell left after the medicine has been absorbed by the body. It is harmless.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with Quinidine?

Some products that may interact with this drug include: large amounts of antacids (e.g., sodium bicarbonate), arbutamine, aripiprazole, atomoxetine, carbonic anhydrase inhibitors (e.g., acetazolamide), cisapride, etravirine, fingolimod, fosamprenavir, loperamide, certain macrolide antibiotics (e.g., erythromycin, clarithromycin), phenytoin, propafenone, quinupristin/dalfopristin, rifamycins (e.g., rifampin, rifabutin).

Other medications can affect the removal of quinidine from your body, which may affect how quinidine works. Examples include cobicistat, mifepristone, certain azole antifungals (including fluconazole, itraconazole, ketoconazole, posaconazole, voriconazole), certain protease inhibitors (such as nelfinavir, ritonavir, tipranavir), among others.

This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include aliskiren, codeine, digoxin, mefloquine, tricyclic antidepressants (such as desipramine, imipramine), among others.

Many drugs besides quinidine may affect the heart rhythm (QT prolongation), including artemether/lumefantrine, ranolazine, toremifene, antiarrhythmic drugs (such as amiodarone, disopyramide, dofetilide, dronedarone, ibutilide, procainamide, sotalol), antipsychotics (such as pimozide, thioridazine, ziprasidone), certain quinolone antibiotics (grepafloxacin, sparfloxacin), among others.

Quinidine is very similar to quinine. Do not use medications containing quinine while using quinidine.

Quinidine may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Quinidine?

Quinidine may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Quinidine?

Quinidine may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this Quinidine.

What is the dose of Quinidine for an adult?

Usual Adult Dose for Arrhythmias

Tablet (sulfate):100 to 600 mg/dose orally every 4 to 6 hours; begin at 200 mg/dose and titrate to desired effect (maximum daily dose: 3 to 4 g).

Extended Release: 324 to 648 mg (gluconate) orally every 8 to 12 hours or 300 to 600 mg (sulfate) orally every 8 to 12 hours.

IV: 800 mg of quinidine gluconate diluted to 50 mL and given at a rate not to exceed 1 mL/min.

Usual Adult Dose for Malaria

Test Dose: 200 mg quinidine sulfate tablet or quinidine gluconate IM injection to determine possibility of idiosyncratic reaction.

Dosage Regimen 1:

Loading dose: 24 mg/kg of quinidine gluconate diluted in 250 mL infused over 4 hours.

Maintenance dose: Start in 24 hours, 12 mg/kg of quinidine gluconate diluted in 250 mL over 4 hours every 8 hours for 7 days or until oral therapy.

Dosage Regimen 2:

Loading dose: 10 mg/kg of quinidine gluconate diluted in 250 mL over 1 to 2 hours.

Maintenance dose: 0.02 mg/kg/min of quinidine gluconate for up to 72 hours.

Omit quinidine loading dose if patient received more than 40 mg/kg of quinine in preceding 48 hours or mefloquine within preceding 12 hours.

Change to oral quinine once parasite density is less than 1% and patient can receive oral medication to complete treatment course; total duration of treatment (quinidine/quinine): 3 days in Africa or South America; 7 days in Southeast Asia; use in combination with doxycycline, tetracycline, or clindamycin.

Renal Dose Adjustments

If creatinine clearance is less than 10 mL/minute, administer 75% of normal dose.

Liver Dose Adjustments

Reduce maintenance dose by 50% and monitor serum levels closely.

Dialysis

Quinidine is slightly hemodialyzable (5%-20%). A 200 mg supplemental dose post hemodialysis dose is recommended. Quinidine is not removed by peritoneal dialysis.

Other Comments

Dosages exceeding 648 mg (gluconate) every 8 hours or 600 mg (sulfate) every 6 hours are not recommended except for patients with relatively large actual body weight.

What is the dose of Quinidine for a child?

Usual Pediatric Dose for Malaria

Test Dose: 200 mg quinidine sulfate tablet or quinidine gluconate IM injection to determine possibility of idiosyncratic reaction.

Dosage Regimen 1:

Loading dose: 24 mg/kg of quinidine gluconate diluted in 250 mL infused over 4 hours.

Maintenance dose: Start in 24 hours, 12 mg/kg of quinidine gluconate diluted in 250 mL over 4 hours every 8 hours for 7 days or until oral therapy.

Dosage Regimen 2:

Loading dose: 10 mg/kg of quinidine gluconate diluted in 250 mL over 1 to 2 hours.

Maintenance dose: 0.02 mg/kg/min of quinidine gluconate for up to 72 hours.

Omit quinidine loading dose if patient received more than 40 mg/kg of quinine in preceding 48 hours or mefloquine within preceding 12 hours.

Change to oral quinine once parasite density is less than 1% and patient can receive oral medication to complete treatment course; total duration of treatment (quinidine/quinine): 3 days in Africa or South America; 7 days in Southeast Asia; use in combination with doxycycline, tetracycline, or clindamycin.

How is Quinidine available?

Quinidine is available in the following dosage forms and strengths:

  • Injectable solution,
  • Oral tablet,
  • Oral tablet, extended release,
  • Compounding powder.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Quinidine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: April 21, 2018 | Last Modified: April 21, 2018

Want to live your best life?
Get the Hello Doktor Daily newsletter for health tips, wellness updates and more.
You might also like