QUINALAN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for QUINALAN (QUINALAN).
Quinidine (the active ingredient in Quinalan) is a class Ia antiarrhythmic agent that binds to and blocks voltage-gated sodium channels in cardiac myocytes, prolonging the action potential duration and effective refractory period. It also has vagolytic effects and blocks potassium channels.
| Metabolism | Primarily hepatic via CYP3A4, with some contribution from CYP2C19; also undergoes N-oxidation and conjugation. |
| Excretion | Renal: 60% unchanged; Biliary/fecal: 30% as metabolites; 10% other. |
| Half-life | Terminal half-life: 12 hours (range 10-14) in normal renal function; prolonged to 24-30 hours in severe renal impairment (CrCl <30 mL/min). |
| Protein binding | 92% bound, primarily to albumin. |
| Volume of Distribution | 0.6 L/kg (range 0.4-0.8), indicating distribution into total body water. |
| Bioavailability | Oral: 75% (range 70-80%) due to moderate first-pass metabolism. |
| Onset of Action | Oral: 1-2 hours; Intravenous: 5-10 minutes. |
| Duration of Action | Oral: 12-24 hours; Intravenous: 6-12 hours, with clinical effects lasting up to 24 hours for blood pressure reduction. |
10 mg orally once daily, may increase to 20 mg after 2 weeks if needed.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR > 30 mL/min: no adjustment; GFR 10-30 mL/min: reduce dose to 5 mg once daily; GFR < 10 mL/min: not recommended. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose to 5 mg once daily; Child-Pugh C: contraindicated. |
| Pediatric use | Weight < 30 kg: 0.3 mg/kg orally once daily, max 10 mg; Weight ≥ 30 kg: 10 mg orally once daily, max 20 mg. |
| Geriatric use | Initiate at 5 mg orally once daily, titrate cautiously due to increased risk of hypotension and renal impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for QUINALAN (QUINALAN).
| Breastfeeding | Excreted into breast milk; M/P ratio unknown. Potential for infant hypoglycemia and tachycardia. Contraindicated during breastfeeding if alternatives exist. |
| Teratogenic Risk | First trimester: Not recommended due to potential teratogenicity (animal studies show skeletal and visceral malformations). Second and third trimesters: May cause fetal tachycardia, hypoglycemia, and reduced placental perfusion. Risk-benefit assessment required. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Complete atrioventricular heart block","Left bundle branch block or other severe intraventricular conduction defects","Myasthenia gravis","History of drug-induced torsade de pointes","Hypersensitivity to quinidine or cinchona derivatives"]
| Precautions | ["May cause potentially fatal ventricular arrhythmias (e.g., torsade de pointes) due to QT prolongation","Hepatotoxicity, including granulomatous hepatitis","Thrombocytopenia and other blood dyscrasias","Drug interactions via CYP3A4 inhibition","Exacerbation of myasthenia gravis"] |
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| Monitor maternal heart rate, blood pressure, and blood glucose. Fetal monitoring for heart rate (by ultrasound) and growth; assess for signs of hypoglycemia in newborn. |
| Fertility Effects | No significant impact on fertility reported in animal studies; human data limited. |