quinidine (Rx)

Brand and Other Names:Quinaglute, Quinidex, more...quinidine gluconate
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Dosing & Uses


Dosage Forms & Strengths


  • 200mg (as sulfate)
  • 300mg (as sulfate)

tablet, extended-release

  • 300mg (as sulfate)
  • 324mg (as gluconate)

injectable solution

  • 80mg/mL (as gluconate) - discontinued from U.S. market


Quinidine Sulfate

  • Test Dose: 200 mg PO quinidine sulfate several hr before full dosage
  • Atrial fibrillation: 300-400 mg PO q6hr
  • PSVT: 400-600 mg PO q2-3hr until paroxysm terminated
  • Atrial/Ventricular Premature Contractions: 200-300 mg PO q6-8hr
  • Maint: 200-400 mg PO q6-8hr or 600 mg of SR PO q8-12hr
  • No more than 3-4 g/day

Quinidine Gluconate

  • 324-660 mg PO q8-12hr
  • Maintenance: 648 mg PO q12hr OR 324-660 mg PO q8hr
  • PSVT: 400 - 600 mg PO q2-3hr until paroxysm is terminated
  • IV: Usual <5 mg/kg (but may need up to 10 mg/kg) at 0.25 mg/kg/min


Quinidine gluconate for injection is no longer available in the U.S.

Quinidine Gluconate

  • Regimen I
  • Load: 24 mg/kg diluted in 250 mL NS IV infusion over 4 hours  
  • Maintenance: Follow by 12 mg/kg IV infusion over 4 hours q8hr beginning 8 hr after initiation of loading dose except in patients able to swallow the same doses of quinidine are administered using 300 mg quinidine sulfate tablets
  • Regimen II
  • Load: 10 mg/kg diluted in 5 mL/kg NS IV over 1-2 hr  
  • Maintenance: Follow by 0.02 mg/kg/min continuous IV infusion; in patients able to swallow oral quinine is administered every 8 hr to give as much quinine as patient received in quinidine q8hr
  • PO regimen: 300 mg quinidine or 650 mg quinine PO q8hr for 3 days (Africa and South America) or 7 days (Southeast Asia) or until parasitemia is reduced to 1%

Dosage Modifications

Hepatic impairment: Not studied

Renal impairment

  • CrCl <10 mL/min: Administer 75% of normal dose
  • CrCl ≥10 L/min: Dose adjustment not necessary

Pseudobulbar Affect (Off-Label)

Excessive laughing or crying, or involuntary emotional expression affects 20-50% of patients with ALS

30 mg PO bid (administer with dextromethorphan)

Dosage Forms & Strengths


  • 200mg (as sulfate)
  • 300mg (as sulfate)

tablet, controlled-release

  • 300mg (as sulfate)
  • 324mg (as gluconate)

injectable solution

  • 80mg/mL


Quinidine sulfate: 30 mg/kg/day or 900 mg/m²/day PO given in 5 divided doses OR 15-60 mg/kg/day divided q6hr PO

Test dose: 2 mg/kg PO quinidine sulfate; test dose not to exceed 200 mg


Quinidine gluconate for injection is no longer available in the U.S.

Load: 10 mg/kg diluted in 5 mL/kg NS IV over 1-2 hr

Maintenance: Follow by 0.02 mg/kg/min continuous IV infusion; in patients able to swallow oral quinine is administered every 8 hr to give as much quinine as patient received in quinidine q8hr

PO regimen: 650 mg quinine PO q8hr for 3 days (Africa and South America) or 7 days (Southeast Asia) or until parasitemia is reduced to 1%



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            Adverse Effects


            Diarrhea (35%)

            Stomach cramping (22%)

            Lightheadedness (15%)

            QTc prolongation (modest prolongation common; excessive prolongation rare & indicates toxicity) (>10%)

            Anorexia (>10%)

            Bitter taste (>10%)

            Diarrhea (>10%)

            Upper GI distress (>10%)

            Nausea (>10%)

            Vomiting (>10%)


            Syncope (1-8%)

            Palpitation (7%), new or worsened arrhythmias (proarrhythmic effect),

            Headache (7%)

            Fatigue (7%)

            Angina (6%)

            Rash (5%)

            Weakness (5%)

            Sleep disturbance (3%)

            Nervousness (2%)

            Tremor (2%)

            Incoordination (1%)

            Blurred vision



            Frequency Not defined





            Night blindness

            Hypersensitivity reactions (eg, fever, hemolytic/aplastic anemia, respiratory arrest, agranulocytosis)

            Systemic lupus erythematosus may occur if taking quinidine for prolonged period of time



            Black Box Warnings

            In patients with various non-life-threatening ventricular arrhythmias, mortality associated with use of quinidine reported to be consistently greater than that associated with use of any of a variety of alternative antiarrhythmic; mortality risk increases with structural heart disease.

            In the case of quinidine used to prevent or defer recurrence of atrial flutter/fibrillation, the drug may increase mortality


            Hypersensitivity to quinidine or cinchona alkaloids

            Myasthenia gravis, thrombocytopenia or developed thrombocytopenic purpura during prior therapy with quinidine or quinine

            Heart block >1st degree

            Idioventricular conduction delays, including patients in complete atrioventricular block (except when artificial pacemaker present)

            Patients adversely affected by anticholinergic activity

            Drugs or conditions that prolong QT interval


            Use caution in acute rheumatic fever, acute thyrotoxicosis, CHF, subacute bacterial endocarditis, syncope

            Electrolyte imbalances due to severe N/V, diarrhea, eating disorders may occur; use caution

            IV administration requires continuous cardiac & blood pressure monitoring

            Dose should be adjusted within range to achieve desired therapeutic effects within therapeutic plasma concentration and in absence of toxic SE

            Avoid grapefruit juice

            Very high dosages may induce abortion in pregnant women due to oxytocic effect

            Extended-release not recommended in children

            When quinidine is administered to patients with atrial flutter/fibrillation, the desired pharmacologic reversion to sinus rhythm may (rarely) be preceded by a slowing of atrial rate with a consequent increase in rate of beats conducted to ventricles; the resulting ventricular rate may be very high (greater than 200 beats per minute) and poorly tolerated; this hazard may be decreased if partial atrioventricular block is achieved prior to initiation of quinidine therapy, using conduction-reducing drugs such as digitalis, verapamil, diltiazem, or a β-receptor blocking agent

            In patients with sick sinus syndrome, quinidine has been associated with marked sinus node depression and bradycardia

            Renal or hepatic dysfunction causes the elimination of quinidine to be slowed, while congestive heart failure causes a reduction in quinidine's apparent volume of distribution. Any of these conditions can lead to quinidine toxicity if dosage is not appropriately reduced

            Because quinidine opposes atrial and A-V nodal effects of vagal stimulation, physical or pharmacological vagal maneuvers undertaken to terminate paroxysmal supraventricular tachycardia may be ineffective in patients receiving quinidine

            In patients without implanted pacemakers who are at high risk of complete atrioventricular block(eg, those with digitalis intoxication, second-degree atrioventricular block, or severe intraventricular conduction defects), quinidine should be used only with caution

            Proarrhythmic effects

            • As with other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs QT interval, and can lead to torsades de pointes, a life-threatening ventricular arrhythmia; the risk of torsades is increased by bradycardia, hypokalemia, hypomagnesemia, or high serum levels of quinidine, but may appear in absence of any of these risk factors
            • The best predictor of this arrhythmia appears to be the length of QTc interval; quinidine should be used with extreme care in patients who have preexisting long-QT syndromes, who have histories of torsades de pointes of any cause, or who have previously responded to quinidine (or other drugs that prolong ventricular repolarization) with marked lengthening of the QT c interval


            • Quinidine-induced thrombocytopenia is an immune-mediated disorder characterized by a drug-dependent antibody that is itself nonreactive, but when soluble drug is present at pharmacologic concentrations, binds tightly to specific platelet membrane glycoproteins, causing platelet destruction
            • Serologic testing for quinidine-specific antibody is commercially available and may be useful for identifying specific cause of thrombocytopenia in individual cases; testing is important because a patient with quinidine-dependent antibodies should not be re-exposed to quinidine
            • Typically, a patient with immune thrombocytopenia will have taken drug for about 1 week or inter­mittently over a longer period of time (possibly years) before presenting with petechiae or bruising
            • Systemic symptoms, such as lightheadedness, chills, fever, nausea, and vomiting, often may precede bleeding events; thrombocytopenia may be severe; patients should have risk/benefit reevaluated in order to continue treatment with quinidine; if drug is stopped, symptoms usually resolve within 1 or 2 days and platelet count returns to normal in less than 1 week
            • If quinidine is not stopped, there is a risk of fatal hemorrhage; the onset of thrombocytopenia may be more rapid upon re-exposure

            Drug interaction overview

            • Interactions with coadministered drugs can alter serum concentration and activity of quinidine, leading either to toxicity or to lack of efficacy if dose of quinidine is not appropriately modified
            • Diltiazem significantly decreases clearance and increases t1/2 of quinidine, but quinidine does not alter the kinetics of diltiazem
            • Drugs that alkalinize urine (carbonic-anhydrase inhibitors, sodium bicarbonate, thiazide diuretics) reduce renal elimination of quinidine
            • By pharmacokinetic mechanisms not well understood, quinidine levels are increased by coadministration of amiodarone or cimetidine
            • Very rarely, and again by mechanisms, not under­stood, quinidine levels are decreased by coadministration of nifedipine
            • Hepatic elimination of quinidine may be accelerated by coadministration of drugs ( phenobarbital, phenytoin, rifampin) that induce production of cytochrome P450 IIIA4; perhaps because of competition for P450 IIIA4 metabolic pathway, quinidine levels rise when ketoconazole is coadministered
            • Coadministration of propranolol usually does not affect quinidine pharmacokinetics, but in some studies, the β-blocker appeared to cause increases in peak serum levels of quinidine, decreases in quinidine's volume of distribution, and decreases in total quinidine clearance
            • The effects (if any) of coadministration of other beta-blockers on quinidine pharmacokinetics have not been adequately studied; hepatic clearance of quinidine is significantly reduced during coadministration of verapamil, with corresponding increases in serum levels and half-life
            • The rate and extent of quinidine absorption may be affected by changes in dietary salt intake; a decrease in dietary salt intake may lead to an increase in plasma quinidine concentrations

            Pregnancy & Lactation


            There are no adequate and well-controlled studies in pregnant women

            Animal reproductive studies have not been conducted


            Lactation: crosses into breast milk, use extreme caution (AAP Committee states compatible with nursing)

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.



            Mechanism of Action

            Class IA (membrane stabilizing) antiarrhythmic agent; inhibits recovery after repolarization resulting in decreasing myocardial excitability & conduction velocity

            Direct membrane depressant that decreases conduction velocity, prolongs refractoriness, decreases automaticity and reduces repolarization abnormalities


            Bioavailability: Sulfate 70%; gluconate 70-80%

            Peak Plasma Time: 2 hr (sulfate); 3-6 hr (gluconate)

            Onset: PO: 1-3 hr

            Duration: 6-8 hr


            Vd: 2-3 L/kg (adults); 0.5 L/kg (heart failure)

            Protein Bound: 80-88% (adults); 50-70% (newborns)


            Metabolism: Liver via hepatic P450 enzyme CYP3A4

            Metabolites: 3-hydroxyquinidine and 2-quinidinone (some have antiarrhythmic effects)

            Enzymes inhibited: CYP2D6


            Half-Life: 6-8 hr (adults); 3-4hr (children)

            Clearance: 3-5 mL/min/kg (adults); 1-2.5 mL/min/kg (children)

            Excretion: Urine (15-25%); feces (5%)

            Dialyzable: HD: Yes; PD: No



            Oral Administration

            May take with or without food



            quinidine gluconate oral
            324 mg tablet

            Copyright © 2010 First DataBank, Inc.


            Patient Handout

            Patient Education
            quinidine gluconate oral

            QUINIDINE - ORAL


            COMMON BRAND NAME(S): Quinidex

            WARNING: Before taking this drug for treatment of an irregular heartbeat, you should discuss your risks and benefits of treatment with your doctor or pharmacist. This drug should be used only in carefully selected patients. Many heart drugs like quinidine (antiarrhythmics) are very effective, but they can rarely cause new serious (possibly fatal) irregular heartbeats.

            USES: This medication 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 (such as "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 TO USE: Before starting this drug, the manufacturer recommends that you take a test dose (usually a smaller amount than your regular dose) to determine whether you are allergic to it. Consult your doctor or pharmacist for details.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 at least 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. Swallow the tablets whole.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.

            SIDE EFFECTS: Diarrhea, nausea, vomiting, loss of appetite, stomach pain/cramps, or a burning feeling in throat or chest (such as heartburn) may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor 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: nausea/vomiting that doesn't stop, vision changes, eye pain, muscle pain, signs of low blood sugar (such as unusual sweating, shakiness), signs of infection (such as sore throat that doesn't go away, fever, chills), easy bruising/bleeding, extreme tiredness, dark urine, yellowing eyes/skin, aching/swollen joints.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.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 or at www.fda.gov/medwatch.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 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 (such as 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 (cannabis) 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 (cannabis).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 (see above).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.Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: large amounts of antacids (such as sodium bicarbonate), arbutamine, aripiprazole, atomoxetine, etravirine, fingolimod, fosamprenavir, loperamide, certain macrolide antibiotics (such as erythromycin, clarithromycin), phenytoin, propafenone, quinupristin/dalfopristin, rifamycins (such as rifampin, rifabutin).Other medications can affect the removal of quinidine from your body, which may affect how quinidine works. Examples include cobicistat, mifepristone, ritonavir, certain azole antifungals (including fluconazole, itraconazole, ketoconazole, posaconazole, voriconazole), certain protease inhibitors (such as nelfinavir, 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.

            OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe dizziness/fainting, hallucinations, seizures.

            NOTES: Do not share this medication with others.Lab and/or medical tests (such as complete blood count, liver/kidney function, quinidine blood levels, EKG) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

            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. Take your next dose at the regular time. Do not double the dose to catch up.

            STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications 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.

            MEDICAL ALERT: Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).

            Information last revised November 2022. Copyright(c) 2022 First Databank, Inc.

            IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.



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            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
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