Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
QUINORA vs CARDIOQUIN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Quinora (quinidine) is a Class Ia antiarrhythmic agent that blocks sodium channels, prolonging the action potential duration and effective refractory period. It also exhibits anticholinergic and negative inotropic effects.
Class IA antiarrhythmic agent; blocks sodium channels, slows phase 0 depolarization, prolongs action potential duration, and increases effective refractory period. Also exhibits anticholinergic and negative inotropic effects.
Treatment of atrial fibrillation and flutter,Ventricular arrhythmias,Off-label: Management of malaria (as quinine derivative)
Conversion and prevention of atrial fibrillation/flutter,Suppression of ventricular arrhythmias,Maintenance of sinus rhythm after cardioversion
325 mg orally every 4 to 6 hours as needed, not to exceed 4 g/day.
Quinidine gluconate extended-release: 324-648 mg orally every 8-12 hours. Quinidine sulfate immediate-release: 200-400 mg orally every 6 hours. Quinidine sulfate extended-release: 300-600 mg orally every 8-12 hours. Maximum dose: 3-4 g/day.
5-7 hours; prolonged in hepatic impairment (up to 12-15 hours) and in elderly patients.
Terminal elimination half-life: 6-8 hours in patients with normal renal function. Prolonged in renal impairment (up to 16-40 hours) and heart failure, requiring dose adjustment.
Primarily hepatic via CYP3A4; also metabolized by CYP2C9 and CYP2E1. Active metabolites include 3-hydroxyquinidine. Renal excretion of unchanged drug accounts for 10-20% of clearance.
Primarily hepatic via CYP3A4; also metabolized by CYP2D6 to active metabolite (3-hydroxyquinidine).
Primarily hepatic (biliary) excretion into feces (~80-90%); renal excretion of unchanged drug accounts for ~10-20%.
Renal: 60-80% as unchanged drug and metabolites (primarily hydroxylated metabolites). Biliary/fecal: 20-40%.
90-95% bound to plasma proteins (primarily albumin and alpha-1-acid glycoprotein).
80-90% bound, primarily to alpha-1-acid glycoprotein (AAG) and albumin.
2.5-3.5 L/kg; extensive tissue distribution with high affinity for cardiac muscle.
Vd: 2-3 L/kg. Large Vd indicates extensive tissue distribution, with high affinity for myocardial tissue.
Oral: ~70-80% (first-pass metabolism reduces bioavailability; food may decrease rate but not extent).
Oral: 70-85% (may be reduced in heart failure). Intravenous: 100%.
GFR 30-50 m L/min: reduce dose by 25%; GFR <30 m L/min: avoid use or prolong dosing interval to every 8 hours.
Cr Cl 30-50 m L/min: administer 75% of normal dose every 8-12 hours. Cr Cl 10-29 m L/min: administer 50% of normal dose every 8-12 hours. Cr Cl <10 m L/min: administer 30% of normal dose every 8-12 hours. Hemodialysis: administer after dialysis on dialysis days.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use.
Child-Pugh Class A: no adjustment necessary. Child-Pugh Class B: reduce dose by 25% and monitor QT interval. Child-Pugh Class C: reduce dose by 50% and monitor QT interval closely.
10-15 mg/kg/dose orally every 4-6 hours; maximum 60 mg/kg/day.
For supraventricular tachyarrhythmias: Quinidine sulfate 15-60 mg/kg/day orally divided every 6 hours; Quinidine gluconate 15-60 mg/kg/day orally divided every 8-12 hours. Maximum single dose: 400 mg. Maximum daily dose: 3 g.
Start at lowest effective dose; consider 325 mg every 6-8 hours due to increased risk of accumulation.
Initiate at lower doses (e.g., quinidine sulfate 200 mg orally every 8-12 hours) and titrate slowly due to decreased renal function and increased risk of QT prolongation and cinchonism. Monitor serum creatinine, QT interval, and quinidine levels. Adjust dose based on renal function.
May cause potentially fatal ventricular arrhythmias (e.g., torsades de pointes) due to QT prolongation. Reserve for patients with life-threatening arrhythmias. Monitor ECG and serum electrolytes. Discontinue if QT interval >50% baseline or QRS duration increases >25%.
May cause fatal arrhythmias (e.g., torsade de pointes, ventricular fibrillation) especially in patients with structural heart disease, hypokalemia, or bradycardia.
May cause cinchonism (tinnitus, headache, visual disturbances). Risk of QT prolongation and torsades de pointes, especially in patients with hypokalemia, bradycardia, or structural heart disease. Hemolytic anemia may occur in G6PD deficiency. Can exacerbate heart failure due to negative inotropic effects. Drug interactions: hepatic enzyme inducers/inhibitors, other QT-prolonging drugs.
Risk of proarrhythmia; monitor ECG, electrolytes, hepatic/renal function; avoid in QT prolongation; may cause cinchonism (tinnitus, hearing loss, visual disturbances); caution in myasthenia gravis, heart failure, and hepatic impairment.
History of QT prolongation or torsades de pointes with quinidine. Myasthenia gravis (due to anticholinergic effects). Complete AV block without pacemaker. Known hypersensitivity (including thrombocytopenia). Major contraindication in malaria caused by Plasmodium falciparum with severe adverse reactions.
Complete AV block without pacemaker,Long QT syndrome,Myasthenia gravis,Hypersensitivity to quinine/quinidine,Cardiogenic shock,Digitalis toxicity
Grapefruit juice increases quinidine levels; avoid concurrent use. Food does not affect absorption significantly; take with or without food. High-fat meals may delay absorption.
Avoid grapefruit and grapefruit juice; they inhibit CYP3A4 metabolism, increasing quinidine levels. Take with food to reduce gastrointestinal upset, but avoid high-potassium foods (e.g., bananas, oranges, spinach) if potassium levels are low.
In first trimester, associated with increased risk of spontaneous abortion and congenital anomalies including cardiovascular and neural tube defects. Second and third trimester exposure may cause premature closure of ductus arteriosus, oligohydramnios, and neonatal renal impairment.
Quinidine, the active ingredient in CARDIOQUIN, is classified as FDA Pregnancy Category C. First trimester: Limited data, but animal studies have shown teratogenic effects at high doses. Second and third trimesters: No adequate well-controlled studies; potential risk of fetal tachycardia, thrombocytopenia, and neonatal coagulopathy. Use only if potential benefit outweighs risk.
Excreted into breast milk; M/P ratio unknown. Due to risk of serious adverse reactions in nursing infants including kernicterus in neonates with G6PD deficiency, contraindicated during breastfeeding.
Quinidine is excreted into breast milk with a milk-to-plasma ratio of approximately 0.7-0.9. Limited data suggest low risk to nursing infant, but monitor for arrhythmias, cinchonism, and thrombocytopenia. Use with caution.
Increased volume of distribution and renal clearance during pregnancy may require dose increase; therapeutic drug monitoring recommended to maintain efficacy.
Increased volume of distribution and renal clearance in pregnancy may require dose adjustments. Monitor serum quinidine levels and titrate to therapeutic effect. Lower starting doses may be needed due to altered protein binding.
Quinora (quinidine) is a class Ia antiarrhythmic; monitor for QT prolongation and torsades de pointes. Use with caution in heart failure, renal impairment, and hepatic dysfunction. Check serum potassium and magnesium levels before initiation. Watch for cinchonism (tinnitus, headache, blurred vision) at high doses. Avoid use with other QT-prolonging drugs. Therapeutic drug monitoring is recommended (target 2-6 mcg/m L).
Cardioquin (quinidine) is a class Ia antiarrhythmic. Monitor QRS and QT intervals; risk of torsades de pointes, especially with hypokalemia or hypomagnesemia. Coadministration with digoxin requires digoxin dose reduction due to decreased clearance. Avoid in patients with myasthenia gravis, as it can exacerbate weakness. Use with caution in hepatic impairment.
Take exactly as prescribed; do not skip doses or double up if missed.,Report any signs of allergic reaction (rash, fever, difficulty breathing) or unusual bleeding/bruising.,Avoid grapefruit juice as it may increase quinidine levels.,Contact your doctor if you experience dizziness, fainting, or palpitations.,Do not stop abruptly; taper as directed to avoid rebound arrhythmias.,Tell all healthcare providers you are taking quinidine.
Take exactly as prescribed; do not skip doses or stop without consulting your doctor.,Report any fainting, rapid heartbeat, or chest pain immediately.,Avoid grapefruit and grapefruit juice; they increase quinidine levels and risk of side effects.,Limit alcohol intake; it may increase side effects like dizziness and drowsiness.,Notify all healthcare providers you are taking quinidine.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about QUINORA vs CARDIOQUIN, answered by our medical review team.
QUINORA is a Antiarrhythmic Agent that works by Quinora (quinidine) is a Class Ia antiarrhythmic agent that blocks sodium channels, prolonging the action potential duration and effective refractory period. It also exhibits anticholinergic and negative inotropic effects.. CARDIOQUIN is a Antiarrhythmic Agent that works by Class IA antiarrhythmic agent; blocks sodium channels, slows phase 0 depolarization, prolongs action potential duration, and increases effective refractory period. Also exhibits anticholinergic and negative inotropic effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between QUINORA and CARDIOQUIN depend on the specific clinical indication. These are both Antiarrhythmic Agent agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of QUINORA is: 325 mg orally every 4 to 6 hours as needed, not to exceed 4 g/day.. The standard adult dose of CARDIOQUIN is: Quinidine gluconate extended-release: 324-648 mg orally every 8-12 hours. Quinidine sulfate immediate-release: 200-400 mg orally every 6 hours. Quinidine sulfate extended-release: 300-600 mg orally every 8-12 hours. Maximum dose: 3-4 g/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between QUINORA and CARDIOQUIN in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. QUINORA is classified as Category C. In first trimester, associated with increased risk of spontaneous abortion and congenital anomalies including cardiovascular and neural tube defects. Second and third trimester exp. CARDIOQUIN is classified as Category C. Quinidine, the active ingredient in CARDIOQUIN, is classified as FDA Pregnancy Category C. First trimester: Limited data, but animal studies have shown teratogenic effects at high . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.