Dosing & Uses
Dosage Forms & Strengths
- Test Dose: 200 mg PO quinidine sulfate several hr before full dosage
- AFib: 300-400 mg PO q6hr
- PSVT: 400-600 mg PO q2-3hr until paroxysm terminated
- Atrial/Ventr Premature Contractions: 200-300 mg PO TID/QID
- Maint: 200-400 mg PO TID/QID or 600 mg of SR PO q8-12hr
- No more than 3-4 g/d
- 324-660 mg PO q8-12hr
- Maint: 648 mg PO q12hr OR 324-660 mg PO q8hr
- PSVT:400 - 600 mg PO q2-3hr until paroxysm is terminated
- IV: usu <5 mg/kg (but may need up to 10 mg/kg) at 0.25 mg/kg/min
Quinidine Sulfate: 300-600 mg OR 10 mg/kg PO q8hr x 5-7 days
- Load: 10 mg/kg diluted in 5 mL/kg NS IV over 1-2 hr, THEN continuous IV infusion of 0.02 mg/kg/min for 72 hr or until parasitemia is reduced to 1% or until oral therapy can be started OR
- Load: 24 mg/kg diluted in 250 mL NS IV infusion over 4 hours
- Maint: after another 4 hr, 12 mg/kg IV infusion over 4 hours q8hr x3 & parasitemia is reduced to less than 1% & oral therapy can be started
- PO: 324-972 mg PO q8-12hr x5-7 days
Pseudobulbar Affect (Off-Label)
Excessive laughing or crying, or involuntary emotional expression affects 20-50% of patients with ALS
30 mg PO bid (administer with dextromethorphan)
Other Indications & Uses
Cardioversion or chronic therapy for atrial fib/flutter, PSVT, malaria
Off-label: prevention of atrial, AV junctional & ventricular premature complexes in adults; paroxysmal atrial tach or AV junctional rhythm, paroxysmal VTach, pseudobulbar affect
Dosage Forms & Strengths
Quinidine Gluconate: 2-10 mg/kg IV q3-6hr PRN
Quinidine Sulfate: 30 mg/kg/day or 900 mg/sq. meter/day PO given in 5 divided doses OR 15-60 mg/kg/day divided q6hr PO
Test Dose: 2 mg/kg PO quinidine sulfate
CDC recommends same wt-based dosing as for adults
Serious - Use Alternative
Significant - Monitor Closely
Stomach cramping (22%)
QTc prolongation (modest prolongation common; excessive prolongation rare & indicates toxicity) (>10%)
Bitter taste (>10%)
Upper GI distress (>10%)
Palpitation (7%), new or worsened arrhythmias (proarrhythmic effect),
Sleep disturbance (3%)
Frequency Not defined
Hypersensitivity rxns (eg, fever, hemolytic/aplastic anemia, respiratory arrest, agranulocytosis)
Systemic lupus erythematosus may occur if taking quinidine for prolonged period of time
Black Box Warnings
Antiarrhythmic drugs have not been shown to enhance survival in non-life-threatening ventricular arrhythmias and they may increase mortality. The mortality risk increases with structural heart disease.
Quinidine may increase mortality in treatment of atrial fibrillation or atrial flutter
Hypersensitivity to quinidine or cinchona alkaloids
Absence of atrial activity, aberrant impulses or abnormal rhythm due to escape mechanisms, complete AV block or AV dissociation, digoxin tox, wide QRS, history of torsades, long QT syndrome, thrombocytopenia, myasthenia gravis, contraindicated w/pregnancy (neonatal thrombocytopenia) and lactation
Drugs or conditions that prolong QT interval
In non-life-threatening ventricular arrhythmias, mortality associated with quinidine was consistently greater than that associated with any of a variety of alternative antiarrhythmics
Acute rheumatic fever, acute thyrotoxicosis, bradycardia, CHF, hypoK or hypoMg, hypotension, incomplete AV block, sick sinus syndrome, subacute bacterial endocarditis, syncope, concomitant use of digoxin, liver dz, renal impairment, pregnancy/lactation
Electrolyte imbalances d/t severe N/V, diarrhea, eating disorders
IV admin requires continuous cardiac & blood pressure monitoring
Low salt diet may incr blood concs
Dose should be adjusted within range to achieve desired therapeutic effects within therapeutic plasma concentration and in absence of toxic SE
Avoid grapefruit juice
Very high dosages may induce abortion in pregnant women d/t oxytocic effect
Ext rel not recommended in children
Pregnancy & Lactation
Pregnancy Category: C
Lactation: crosses into breast milk, use extreme caution (AAP Committee states compatible w/ nursing)
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Half-Life: 6-8 hr
Onset: PO: 1-3 hr
Duration: 6-8 hr
Peak Plasma Time: PO, conv: 1-2 hr PO, ext rel: 3-5 hr
Bioavailability: sulfate 70%; gluconate 70-80%
Protein Bound: ~80%
Vd: 2-3 L/kg
Metabolism: liver via hepatic P450 enzyme CYP3A4
Metabolites: 3-hydroxyquinidine & 2-quinidinone (some have antiarrhythmic effects)
Dialyzable: HD: yes; PD: no
Enzymes inhibited: CYP2D6
Mechanism of Action
Class IA (membrane stabilizing) antiarrhythmic agent; inhibits recovery after repolarization resulting in decreasing myocardial excitability & conduction velocity
Direct membrane depressant that decreases conduction velocity, prolongs refractoriness, decreases automaticity and reduces repolarization abnormalities
Additive: diazepam, ranitidine, verapamil
Additive: alkalines, amiodarone, furosemide, iodide
Dilute 800 mg quinidine gluconate (10 mL) to 50 mL w/ D5W
Minimize use of PVC tubing
IV Administration: see dosing
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