Quinidine

Aka: Quinidine, Quinaglute

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II. Indications

  1. Multifocal Atrial Tachycardia
  2. Atrial Fibrillation Chemical Cardioversion
    1. Time to Cardioversion: 3-6 hours
    2. Conversion Rate: 38-86%
    3. Chronic Efficacy: 47-60%
  3. Life Threatening Malaria

III. Contraindications

  1. Complete AV Block
  2. Left Bundle Branch Block

IV. Mechanism

  1. Class Ia Antiarrhythmic (Sodium Channel Blocker, lengthens Action Potential duration)
  2. Similar activity as with Procainamide and Disopyramide
  3. Decreases the automaticity of ectopic foci
  4. Outside of nodes, increases heart refractory period including accessory pathways
  5. Decreases conduction velocity in the atria, HIs Bundle and Purkinje Fibers
    1. Paradoxically may increase AV Nodal conduction in rapid atrial rates due to Anticholinergic activity
    2. Results in QRS Widening and QTc Prolongation

V. Precautions

  1. Consider initial hospital-based telemetry monitoring when starting Quinidine

VI. Dosing: Arrhythmia

  1. Primarily oral route (IV risks Hypotension, pain with IM Injection)
  2. Adult
    1. Quinidine Gluconate extended-release 324 to 648 mg orally every 8 to 12 hours
    2. Quinidine Sulfate immediate-release 200 to 400 mg orally every 6 to 8 hours
    3. Quinidine Sulfate extended-release 300 to 600 mg orally every 8 to 12 hours
  3. Child
    1. Quinidine Sulfate immediate-release
      1. Start (Test Dose): 2 mg/kg up to 200 mg
      2. Target: 15 to 60 mg orally every 6 hours

VII. Dosing: Life-Threatening Malaria

  1. Load Quinidine Gluconate 10 mg/kg (up to max 600 mg) IV over 1 to 2 hours
  2. Maintain Quinidine Gluconate 0.02 mg/kg/min for >= 24 hours
  3. Transition to oral quinine or similar when Parasitemia <1%

VIII. Pharmacokinetics

  1. Protein Bound: 90%
  2. Hepatic metabolism with renal excretion

IX. Adverse Effects

  1. Common
    1. Gastrointestinal (Nausea, Vomiting, Diarrhea)
  2. Serious
    1. Proarrhythmic
      1. Torsades de Pointes (Quinidine prolongs QTc)
      2. Ventricular increased response to Atrial Tachycardia
    2. Thrombotic Thrombocytopenic Purpura
    3. Mortality is increased when used in non-lethal Arrhythmia and comorbid CAD, CHF
    4. Cinchonism
      1. Neural, Retinal, and auditory toxicity related to Quinolones

X. Drug Interactions

  1. Quinidine increased metabolism with decreased effects
    1. Phenobarbital
    2. Phenytoin
  2. Quinidine potentiates other drugs
    1. Digoxin
    2. Vasodilators (increased risk of Hypotension)
    3. Warfarin

XI. Safety

  1. Pregnancy Category C
  2. Considered safe in Lactation

XII. Resources

  1. Quinidine Sulfate Tablet (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b0d6341b-d880-4f0b-8844-bc788c03004a
  2. Quinidine Gluconate Extended Release (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ad2ad985-cca2-25b5-e053-2995a90a402f

XIII. References

  1. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 74-5
  2. Hamilton (2020) Tarascon Pocket Pharmacopoeia

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