Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
TIKOSYN vs QUINORA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Selective class III antiarrhythmic agent; blocks cardiac potassium channels (IKr), prolonging action potential duration and effective refractory period.
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.
Conversion of atrial fibrillation/atrial flutter to normal sinus rhythm,Maintenance of normal sinus rhythm in patients with symptomatic atrial fibrillation/atrial flutter
Treatment of atrial fibrillation and flutter,Ventricular arrhythmias,Off-label: Management of malaria (as quinine derivative)
500 mcg orally twice daily for atrial fibrillation/flutter conversion and maintenance of sinus rhythm.
325 mg orally every 4 to 6 hours as needed, not to exceed 4 g/day.
10 hours (terminal) in patients with normal renal function; prolonged to up to 42 hours in severe renal impairment; clinically relevant for dosing interval adjustment.
5-7 hours; prolonged in hepatic impairment (up to 12-15 hours) and in elderly patients.
Primarily metabolized by CYP3A4; also undergoes N-dealkylation and glucuronidation; renal excretion of unchanged drug (20-30%) and metabolites.
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.
Renal: 80% as unchanged drug; biliary/fecal: 20% (metabolites and minor parent drug).
Primarily hepatic (biliary) excretion into feces (~80-90%); renal excretion of unchanged drug accounts for ~10-20%.
96% bound to plasma proteins (primarily albumin).
90-95% bound to plasma proteins (primarily albumin and alpha-1-acid glycoprotein).
3 L/kg (range 2-4 L/kg), indicating extensive tissue distribution, particularly to cardiac tissue.
2.5-3.5 L/kg; extensive tissue distribution with high affinity for cardiac muscle.
>90% after oral administration (approximately 93% with low first-pass metabolism).
Oral: ~70-80% (first-pass metabolism reduces bioavailability; food may decrease rate but not extent).
Cr Cl > 60 m L/min: 500 mcg BID. Cr Cl 40-60 m L/min: 250 mcg BID. Cr Cl < 40 m L/min: contraindicated.
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.
No formal Child-Pugh based adjustment; use caution in severe hepatic impairment due to limited data.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 50%; Child-Pugh Class C: avoid use.
Safety and efficacy not established in pediatric patients.
10-15 mg/kg/dose orally every 4-6 hours; maximum 60 mg/kg/day.
Adjust based on renal function per Cr Cl; monitor QTc interval closely due to increased risk of toxicity.
Start at lowest effective dose; consider 325 mg every 6-8 hours due to increased risk of accumulation.
Tikosyn can cause life-threatening ventricular arrhythmias (e.g., torsade de pointes) and must be initiated in a hospital setting with continuous ECG monitoring and dose adjustment based on creatinine clearance and QTc interval.
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%.
QTc prolongation; hypokalemia; hypomagnesemia; renal impairment; bradycardia; concurrent use of other QT-prolonging drugs; drug interactions with CYP3A4 inhibitors.
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.
Baseline QTc > 440 msec (500 msec in ventricular conduction abnormalities); severe renal impairment (Cr Cl < 20 m L/min); concurrent use of verapamil, cimetidine, ketoconazole, trimethoprim, or other drugs that prolong QT; congenital long QT syndrome; history of torsade de pointes; hypersensitivity to dofetilide.
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.
Grapefruit juice inhibits CYP3A4, increasing dofetilide levels and risk of arrhythmia; avoid grapefruit and grapefruit juice. High-potassium foods (e.g., bananas, oranges, spinach) are generally safe but must be consumed consistently to avoid electrolyte fluctuations. Avoid excessive licorice intake which can cause hypokalemia.
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.
Pregnancy Category C. Animal studies have shown fetal toxicity (increased fetal loss, reduced fetal weight) at maternally toxic doses. No adequate and well-controlled studies in pregnant women. Potential fetal risks in all trimesters; use only if benefit justifies risk.
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.
Not recommended. It is unknown if TIKOSYN is excreted in human milk. M/P ratio not available. Potential for serious adverse reactions in nursing infants; discontinue nursing or drug.
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.
Dosing adjustments not specifically defined for pregnancy. Use standard dosing based on renal function and QTc interval. However, due to potential pharmacokinetic changes in pregnancy (increased volume of distribution, altered clearance), monitor drug levels (if available) and adjust dose cautiously, targeting therapeutic QTc effect.
Increased volume of distribution and renal clearance during pregnancy may require dose increase; therapeutic drug monitoring recommended to maintain efficacy.
TIKOSYN (dofetilide) is a class III antiarrhythmic indicated for maintenance of sinus rhythm in patients with atrial fibrillation/flutter. Requires inpatient initiation with continuous ECG monitoring due to risk of torsade de pointes. Dosing is based on creatinine clearance and QTc interval; must not exceed 500 mcg twice daily. Drug interactions via CYP3A4 and renal clearance are critical; avoid verapamil, cimetidine, ketoconazole, and trimethoprim. Hypokalemia and hypomagnesemia must be corrected before use.
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).
You must be hospitalized for the first 3 days of treatment to monitor your heart rhythm.,Do not take any new medications, including over-the-counter drugs or herbal supplements, without consulting your doctor.,Report any fainting, lightheadedness, or palpitations immediately.,Take your dose exactly as prescribed, usually twice daily with or without food.,Do not skip doses or double up if you miss a dose; call your doctor if you miss more than one dose.,Avoid grapefruit juice and grapefruit products while on this medication.,Your kidney function will be checked regularly; keep all lab appointments.,Inform all healthcare providers that you are taking TIKOSYN.
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.
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 TIKOSYN vs QUINORA, answered by our medical review team.
TIKOSYN is a Antiarrhythmic Agent that works by Selective class III antiarrhythmic agent; blocks cardiac potassium channels (IKr), prolonging action potential duration and effective refractory period.. 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between TIKOSYN and QUINORA 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 TIKOSYN is: 500 mcg orally twice daily for atrial fibrillation/flutter conversion and maintenance of sinus rhythm.. The standard adult dose of QUINORA is: 325 mg orally every 4 to 6 hours as needed, not to exceed 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 TIKOSYN and QUINORA 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. TIKOSYN is classified as Category C. Pregnancy Category C. Animal studies have shown fetal toxicity (increased fetal loss, reduced fetal weight) at maternally toxic doses. No adequate and well-controlled studies in pr. 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. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.