Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CIN-QUIN vs NORPACE CR
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 Ia antiarrhythmic agent; decreases myocardial excitability and conduction velocity, and prolongs refractory period by blocking sodium channels.
Treatment of atrial fibrillation and flutter,Paroxysmal supraventricular tachycardia,Ventricular arrhythmias,Maintenance of sinus rhythm after cardioversion
Treatment of documented life-threatening ventricular arrhythmias (e.g., sustained ventricular tachycardia),Off-label: prevention of atrial fibrillation recurrence, maintenance of sinus rhythm in atrial flutter
Quinine sulfate 648 mg (two 324 mg capsules) orally every 8 hours for 7 days, in combination with doxycycline, tetracycline, or clindamycin.
Disopyramide controlled-release: 200 mg orally every 12 hours; maximum 400 mg/day.
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: 6-12 hours (normal renal function); prolonged to 12-20 hours in renal impairment. In coronary artery disease, half-life may be extended due to reduced clearance.
Metabolized primarily by CYP3A4 to active metabolites (3-hydroxyquinidine and quinidine-N-oxide).
Primarily hepatic via CYP3A4; also excreted renally.
Primarily hepatic metabolism; renal excretion of unchanged drug <20%. Biliary/fecal excretion accounts for ~30% of total clearance.
Renal (50-57% unchanged), hepatic metabolism (30-40%), fecal (<10%). Dose adjustment required for Cr Cl <40 m L/min.
Approximately 70-80% bound, primarily to alpha-1-acid glycoprotein and, to a lesser extent, albumin.
30-50% bound to albumin, alpha-1-acid glycoprotein, and lipoproteins.
Apparent volume of distribution (Vd) is 1.5-2.5 L/kg, indicating extensive tissue distribution.
0.6-1.2 L/kg; larger Vd in heart failure (up to 2.0 L/kg) due to reduced tissue binding.
Oral bioavailability is approximately 80% in healthy subjects; may be reduced in patients with malaria due to impaired absorption.
Oral immediate-release: 70-80%; extended-release: 60-70% (first-pass metabolism). IV: 100%.
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: 200 mg loading dose, then 100 mg every 12 hours. GFR 15-30 m L/min: 200 mg loading dose, then 100 mg every 24 hours. GFR <15 m L/min: 200 mg loading dose, then 100 mg every 48-72 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 B or C: Reduce dose by 50% and titrate carefully; monitor ECGs.
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.
Not recommended for pediatric use; safety and efficacy not established.
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 lower dose (e.g., 100 mg every 12 hours of controlled-release) due to increased risk of anticholinergic effects and renal impairment; monitor renal function and QT interval.
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.
May cause widening of QRS complex and prolongation of QT interval, increasing risk of torsade de pointes and sudden death. Avoid use with other drugs that prolong QT interval. Use only for life-threatening arrhythmias.
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
Can worsen arrhythmias (proarrhythmic); monitor ECG, electrolytes; adjust dose in renal/hepatic impairment; avoid in patients with pre-existing QT prolongation, hypokalemia, or bradycardia.
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), cardiogenic shock, congenital QT prolongation, concurrent use of other QT-prolonging drugs, hypersensitivity to disopyramide.
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.
Avoid grapefruit juice as it may increase disopyramide levels. High-fat meals may delay absorption but do not significantly affect overall bioavailability; take consistently with or without food.
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.
FDA Pregnancy Category C. First trimester: Evidence of teratogenicity in animal studies (increased fetal resorption and skeletal abnormalities) but no adequate human studies. Second and third trimesters: May cause fetal bradycardia, hypoglycemia, and preterm labor due to beta-blockade effects; avoid use unless benefit outweighs risk.
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 human breast milk; M/P ratio approximately 0.5-1.0. Limited data suggests low infant exposure but potential for hypoglycemia and bradycardia; caution advised. American Academy of Pediatrics considers disopyramide compatible with breastfeeding with monitoring.
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.
No formal dosing guidelines established. Pregnancy may alter pharmacokinetics (increased volume of distribution and clearance), potentially requiring dose adjustments. Therapeutic drug monitoring is recommended to maintain trough disopyramide levels between 2-5 mcg/m L. Due to proarrhythmic risks, use lowest effective dose and monitor closely.
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 CR (disopyramide phosphate) is a Class Ia antiarrhythmic with strong anticholinergic effects; monitor for urinary retention, constipation, and dry mouth. It has negative inotropic effects and should be avoided in patients with compensated heart failure or cardiomyopathy. Dosage adjustment required in renal impairment (Cr Cl <40 m L/min). Therapeutic drug monitoring recommended (target 2-5 mcg/m L).
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.
Do not crush or chew extended-release tablets; swallow whole.,Take at regular 12-hour intervals to maintain steady drug levels.,Avoid driving or operating machinery until you know how this medication affects you (may cause dizziness or blurred vision).,Report signs of hypoglycemia (sweating, shakiness) in diabetic patients, as disopyramide can lower blood sugar.,Maintain adequate fluid intake to prevent constipation.,Inform all healthcare providers you are taking this medication, especially before surgery or dental procedures.
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 CR, 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 CR is a Antiarrhythmic (Class Ia) that works by Class Ia antiarrhythmic agent; decreases myocardial excitability and conduction velocity, and prolongs refractory period by blocking sodium channels.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CIN-QUIN and NORPACE CR 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 CR is: Disopyramide controlled-release: 200 mg orally every 12 hours; maximum 400 mg/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 CIN-QUIN and NORPACE CR 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 CR is classified as Category C. FDA Pregnancy Category C. First trimester: Evidence of teratogenicity in animal studies (increased fetal resorption and skeletal abnormalities) but no adequate human studies. Secon. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.