CIN-QUIN
Clinical safety rating
cautionComprehensive clinical and safety monograph for CIN-QUIN (CIN-QUIN).
Comprehensive clinical and safety monograph for CIN-QUIN (CIN-QUIN).
Treatment of atrial fibrillation and flutterParoxysmal supraventricular tachycardiaVentricular arrhythmiasMaintenance of sinus rhythm after cardioversion
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.
| Metabolism | Metabolized primarily by CYP3A4 to active metabolites (3-hydroxyquinidine and quinidine-N-oxide). |
| Excretion | Primarily hepatic metabolism; renal excretion of unchanged drug <20%. Biliary/fecal excretion accounts for ~30% of total clearance. |
| Half-life | Terminal elimination half-life is approximately 4-5 hours in healthy volunteers; prolonged to 8-12 hours in severe malaria or hepatic impairment. |
| Protein binding | Approximately 70-80% bound, primarily to alpha-1-acid glycoprotein and, to a lesser extent, albumin. |
| Volume of Distribution | Apparent volume of distribution (Vd) is 1.5-2.5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is approximately 80% in healthy subjects; may be reduced in patients with malaria due to impaired absorption. |
| Onset of Action | Intravenous: 15-30 minutes; oral: 1-3 hours. |
| Duration of Action | Clinical effect persists for 6-8 hours after intravenous dose; oral administration provides coverage for 8-12 hours. |
| Molecular Weight | 324.42 |
Quinine sulfate 648 mg (two 324 mg capsules) orally every 8 hours for 7 days, in combination with doxycycline, tetracycline, or clindamycin.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (GFR <10 mL/min), reduce dose by one-third to one-half (e.g., 324 mg every 8 hours) and monitor for toxicity. |
| Liver impairment | 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. |
| Pediatric use | 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. |
| Geriatric use | 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. |
| 1st trimester | Avoid. Toxicity data limited; potential for fetal harm. |
| 2nd trimester | Use only if clearly needed. Monitor for maternal arrhythmias. |
| 3rd trimester | Use with caution near term; risk of neonatal arrhythmias. |
Clinical note
Comprehensive clinical and safety monograph for CIN-QUIN (CIN-QUIN).
| Placental transfer | Quinidine crosses the placenta readily; fetal serum concentrations can reach those in maternal serum. |
| Breastfeeding | Quinidine is excreted into breast milk in small amounts (milk:plasma ratio about 0.5). While considered compatible with breastfeeding, monitor infant for potential adverse effects such as arrhythmias or cinchonism. |
| Lactation Rating | L3 - Moderately Safe |
| Teratogenic Risk | 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. |
| Fetal Monitoring | Maternal: serum quinine levels (therapeutic range 8-15 mg/L), glucose (risk of hypoglycemia), ECG for QTc prolongation. Fetal: ultrasound for growth and amniotic fluid volume; fetal heart rate monitoring during administration for preterm labor (if used as abortifacient). |
| Fertility Effects | Quinine has no known direct effect on fertility in males or females. Theoretical risk due to interference with DNA replication, but no clinical data indicate significant impairment. |
■ FDA Black Box Warning
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.
| Serious Effects |
Myasthenia gravisHypersensitivity to quinidine or cinchona alkaloidsAtrioventricular block (complete or high-grade) without a pacemakerThrombocytopenic purpura with previous quinidine therapy
| Precautions | 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 |
| Food/Dietary | 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. |
| Clinical Pearls | 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). |
| Patient Advice | 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. |
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