Drug Guide
Quinidine Gluconate
Classification
Therapeutic: Antiarrhythmic agent
Pharmacological: Class Ia sodium channel blocker
FDA Approved Indications
- Treatment of atrial fibrillation and atrial flutter with rapid ventricular response
- Control of ventricular arrhythmias
Mechanism of Action
Blockade of fast sodium channels in cardiac myocytes, leading to slowed conduction and prolonged refractory period, thereby stabilizing cardiac rhythm.
Dosage and Administration
Adult: Initial dose typically 600-900 mg over 24 hours, titrated based on response and clinical assessment.
Pediatric: Not commonly used; consult specialist for pediatric dosing.
Geriatric: Start at lower doses; monitor closely due to increased risk of adverse effects.
Renal Impairment: Adjust dose based on renal function; monitor renal status.
Hepatic Impairment: Use with caution; no specific dose adjustment but monitor for toxicity.
Pharmacokinetics
Absorption: Variable; generally well absorbed orally.
Distribution: Widely distributed; crosses placenta, appears in breast milk.
Metabolism: Primarily hepatic via CYP enzymes.
Excretion: Renal and biliary excretion.
Half Life: Approx. 6-8 hours, but variable depending on patient factors.
Contraindications
- Complete heart block without pacemaker
- Torsades de pointes
- Uncontrolled heart failure
Precautions
- Use with caution in patients with systolic heart failure, in the elderly, and in hepatic impairment.
- Monitor EKG and blood counts regularly.
Adverse Reactions - Common
- Diarrhea (Occasional)
- Nausea (Rare)
- Gastrointestinal discomfort (Rare)
Adverse Reactions - Serious
- Torsades de pointes (a form of ventricular tachycardia) (Rare)
- Hypotension or bradycardia (Rare)
- Thrombocytopenia (Rare)
- Hemolytic anemia (Rare)
Drug-Drug Interactions
- Digitalis glycosides (may increase toxicity)
- Medicines that prolong the QT interval (risk of arrhythmias)
- CYP3A4 inhibitors and inducers
Drug-Food Interactions
- Avoid grapefruit juice; influences CYP metabolism
Drug-Herb Interactions
- St. John's Wort
Nursing Implications
Assessment: Monitor for arrhythmia control (ECG), blood counts, liver function, and electrolyte levels.
Diagnoses:
- Risk for imbalanced fluid volume
- Risk for arrhythmia
Implementation: Administer with food to reduce gastrointestinal upset; monitor cardiac rhythm regularly.
Evaluation: Assess for resolution of arrhythmias and monitor for adverse effects.
Patient/Family Teaching
- Inform about symptoms of arrhythmias or adverse effects.
- Encourage adherence to prescribed dosing and monitoring schedule.
- Advise to avoid grapefruit juice and certain other foods and medications.
Special Considerations
Black Box Warnings:
- Proarrhythmic effects, including Torsades de pointes
Genetic Factors: CYP2D6 poor metabolizers may have higher plasma levels.
Lab Test Interference: May cause false-positive urinary catecholamine tests.
Overdose Management
Signs/Symptoms: PVCs, ventricular tachycardia, bradycardia, hypotension, dizziness.
Treatment: Discontinue drug immediately, provide supportive care, correct electrolyte imbalances, administer magnesium sulfate for torsades, and perform cardioversion if necessary.
Storage and Handling
Storage: Store at room temperature, away from moisture and light.
Stability: Stable for the duration of the expiration date on the package.