Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CIN-QUIN vs NORPACE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Cin-Quin (quinidine) is a class Ia antiarrhythmic agent that blocks sodium channels, prolonging the effective refractory period and slowing conduction velocity. It also has anticholinergic and alpha-adrenergic blocking properties.
Class Ic antiarrhythmic agent; blocks voltage-gated sodium channels, slowing conduction velocity and prolonging refractory periods in cardiac tissue.
Treatment of atrial fibrillation and flutter,Paroxysmal supraventricular tachycardia,Ventricular arrhythmias,Maintenance of sinus rhythm after cardioversion
Treatment of documented life-threatening ventricular arrhythmias, such as sustained ventricular tachycardia,Off-label: Atrial fibrillation, atrial flutter, supraventricular tachycardia
Quinine sulfate 648 mg (two 324 mg capsules) orally every 8 hours for 7 days, in combination with doxycycline, tetracycline, or clindamycin.
150 mg orally every 6 hours (maximum 300 mg per dose), extended-release formulation 300 mg every 12 hours.
Terminal elimination half-life is approximately 4-5 hours in healthy volunteers; prolonged to 8-12 hours in severe malaria or hepatic impairment.
Terminal elimination half-life: 6-8 hours (normal renal function); prolonged in renal impairment (up to 24 hours).
Metabolized primarily by CYP3A4 to active metabolites (3-hydroxyquinidine and quinidine-N-oxide).
Extensively metabolized in the liver primarily by CYP2D6; also involves CYP1A2 and CYP3A4 to a minor extent. Active metabolite: desethylnorpace.
Primarily hepatic metabolism; renal excretion of unchanged drug <20%. Biliary/fecal excretion accounts for ~30% of total clearance.
Renal: 40-60% unchanged; biliary/fecal: minor (10-20%).
Approximately 70-80% bound, primarily to alpha-1-acid glycoprotein and, to a lesser extent, albumin.
80-90%, primarily to alpha-1-acid glycoprotein and albumin.
Apparent volume of distribution (Vd) is 1.5-2.5 L/kg, indicating extensive tissue distribution.
1.8-3.6 L/kg; large, indicating extensive tissue distribution.
Oral bioavailability is approximately 80% in healthy subjects; may be reduced in patients with malaria due to impaired absorption.
Oral: 80-90%.
No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (GFR <10 m L/min), reduce dose by one-third to one-half (e.g., 324 mg every 8 hours) and monitor for toxicity.
GFR 30-50 m L/min: 150 mg every 12-24 hours; GFR 15-29 m L/min: 150 mg every 24-48 hours; GFR <15 m L/min (not on dialysis): 150 mg every 48 hours or 100 mg every 24 hours.
No specific guidelines for Child-Pugh classification; use with caution in severe hepatic impairment (Child-Pugh C) and consider dose reduction by 50% based on clinical response and monitoring of serum levels.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 25-50% with monitoring; Child-Pugh Class C: contraindicated or use with extreme caution.
For malaria: quinine sulfate 10 mg/kg (base) orally every 8 hours for 7 days (maximum 650 mg/dose) in combination with a second agent.
<1 year: 10-30 mg/kg/day divided every 6 hours; 1-4 years: 10-30 mg/kg/day divided every 6 hours; 4-12 years: 10-30 mg/kg/day divided every 6 hours; 12-18 years: 150-300 mg every 6 hours. Maximum 800 mg/day.
No specific dose adjustments recommended, but start at lower end of dosing range (e.g., 324 mg every 8 hours) due to age-related renal function decline and increased risk of QT prolongation.
Initiate at 100 mg every 6 hours; consider lower doses due to age-related renal decline; monitor for anticholinergic effects and QT prolongation.
Quinidine has been associated with thrombocytopenic purpura and may exacerbate arrhythmias (proarrhythmia). It should be used with caution in patients with severe heart disease or preexisting arrhythmias.
None
May cause QT prolongation and torsades de pointes, especially in patients with hypokalemia, hypomagnesemia, or bradycardia,Cinchonism (tinnitus, hearing loss, blurred vision, nausea) may occur at high doses,Hepatic toxicity and hypersensitivity reactions (including thrombocytopenia),Monitor serum potassium and magnesium levels,Avoid use with other drugs that prolong QT interval
Proarrhythmic effects (e.g., new or worsened arrhythmias, torsades de pointes),Heart failure exacerbation,Hepatic impairment,Renal impairment,Electrolyte disturbances (hypokalemia, hypomagnesemia),Conduction disturbances (e.g., QT prolongation, heart block)
Hypersensitivity to quinidine or cinchona alkaloids,Complete AV block without pacemaker,Myasthenia gravis,Digitalis toxicity,History of drug-induced torsades de pointes or QT prolongation
Pre-existing second- or third-degree AV block unless pacemaker is present,Cardiogenic shock,Severe heart failure,QTc interval > 450 ms,Concomitant use of other QT-prolonging drugs,Hypersensitivity to disopyramide or any component
Avoid grapefruit and grapefruit juice (increases quinidine exposure). Limit caffeine intake as quinidine may enhance its effects. Maintain adequate potassium and magnesium intake; hypokalemia and hypomagnesemia increase arrhythmia risk.
Grapefruit juice may increase disopyramide levels; avoid concurrent intake. High-fat meals may delay absorption; take consistently with or without food. Avoid excessive alcohol, which can exacerbate hypotension and arrhythmias.
CIN-QUIN (quinine) is contraindicated in pregnancy due to teratogenicity. First trimester: risk of congenital malformations (e.g., auditory nerve hypoplasia, limb defects). Second and third trimesters: may cause fetal hypoxia and hypoglycemia; avoid use for malaria prophylaxis. Only in severe falciparum malaria when no alternative exists.
First trimester: No evidence of increased risk of congenital malformations in human studies, but animal studies are insufficient. Second and third trimesters: Risk of fetal bradycardia, QT prolongation, and neonatal depression at delivery. Disopyramide may stimulate uterine contractions, increasing risk of preterm labor.
Quinine is excreted into breast milk in small amounts. M/P ratio approximately 0.2-0.5. Limited data suggest low risk to infant; however, monitor for signs of cinchonism (e.g., fever, rash, restlessness).
Disopyramide is excreted in breast milk with an M/P ratio of approximately 1:1.1. The relative infant dose is about 2–10% of the maternal weight-adjusted dose. Monitor infant for bradycardia, QT changes, and hypoglycemia. Alternative agents preferred unless benefit outweighs risk.
Pregnancy increases clearance and volume of distribution of quinine; dose adjustments are not well-defined. For severe malaria, standard dosing (600 mg oral quinine sulfate every 8 hours for 7 days) is used, but therapeutic drug monitoring is recommended.
Increased renal clearance and volume of distribution in pregnancy may reduce disopyramide serum concentrations. Therapeutic drug monitoring recommended; dose adjustments may be required to maintain efficacy, but empirical increases are not routinely recommended due to risk of uterine contractions and fetal effects. Plasma protein binding is unchanged.
Cin-Quin is a brand of quinidine, a class Ia antiarrhythmic. Monitor QTc interval; risk of torsades de pointes. Avoid in patients with myasthenia gravis due to neuromuscular blocking effects. Use with caution in hepatic impairment. Can cause cinchonism (tinnitus, headache, nausea).
NORPACE (disopyramide) is a Vaughan Williams Class Ia antiarrhythmic with negative inotropic effects; avoid in patients with heart failure or reduced LVEF. Monitor QRS and QT intervals; torsades de pointes risk. Adjust dose in renal impairment. Anticholinergic side effects (dry mouth, urinary retention, blurred vision) are common.
Take exactly as prescribed; do not skip doses or double up.,Report any rapid or irregular heartbeat, fainting, or severe dizziness.,Avoid grapefruit juice as it can increase quinidine levels.,Do not use with over-the-counter products containing quinine or quinidine.,Tell your doctor if you have liver disease, myasthenia gravis, or low potassium/magnesium.,Quinidine can cause diarrhea; contact your doctor if persistent.,You may experience ringing in the ears or blurred vision; notify your prescriber.
Take exactly as prescribed; do not miss doses or double up.,Avoid driving if you experience blurred vision or dizziness.,Report chest pain, shortness of breath, fainting, or rapid heartbeat immediately.,May cause dry mouth; sugarless gum or candy can help.,Avoid alcohol and grapefruit juice without consulting your doctor.,Do not stop abruptly; gradual tapering may be needed.
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 CIN-QUIN vs NORPACE, answered by our medical review team.
CIN-QUIN is a Antiarrhythmic (Class Ia) that works by Cin-Quin (quinidine) is a class Ia antiarrhythmic agent that blocks sodium channels, prolonging the effective refractory period and slowing conduction velocity. It also has anticholinergic and alpha-adrenergic blocking properties.. NORPACE is a Antiarrhythmic (Class Ia) that works by Class Ic antiarrhythmic agent; blocks voltage-gated sodium channels, slowing conduction velocity and prolonging refractory periods in cardiac tissue.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CIN-QUIN and NORPACE depend on the specific clinical indication. These are both Antiarrhythmic (Class Ia) agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CIN-QUIN is: Quinine sulfate 648 mg (two 324 mg capsules) orally every 8 hours for 7 days, in combination with doxycycline, tetracycline, or clindamycin.. The standard adult dose of NORPACE is: 150 mg orally every 6 hours (maximum 300 mg per dose), extended-release formulation 300 mg every 12 hours.. 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 CIN-QUIN and NORPACE 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. CIN-QUIN is classified as Category C. CIN-QUIN (quinine) is contraindicated in pregnancy due to teratogenicity. First trimester: risk of congenital malformations (e.g., auditory nerve hypoplasia, limb defects). Second . NORPACE is classified as Category C. First trimester: No evidence of increased risk of congenital malformations in human studies, but animal studies are insufficient. Second and third trimesters: Risk of fetal bradyca. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.