Pharm

Disopyramide

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Disopyramide, Norpace

  • See Also
  1. Antiarrhythmic
  2. Ventricular Tachycardia
  3. Quinidine
  4. Procainamide
  • Indications
  1. Life-Threatening Ventricular Arrhythmia (e.g. Ventricular Tachycardia)
    1. Disopyramide is rarely indicated (other options preferred)
  2. Atrial Fibrillation Rhythm Control (maintain sinus rhythm)
  • Contraindications
  1. QT Prolongation
  2. Torsades de Pointes history
  3. Cardiogenic Shock
  4. Second or Third Degree AV Block
  • Precautions
  1. Proarrhythmic
    1. Consider starting while in hospital on telemetry monitoring
  2. Higher mortality in structural heart disease (Systolic Dysfunction, Myocardial Infarction)
  • Mechanism
  1. Similar to other Class 1A anti-arrhythmics (e.g. Quinidine, Procainamide)
  2. Class 1A anti-arrhythmic
    1. Blocks the fast Sodium channel in cardiac cell membranes within atrial and ventricular tissues
    2. Slows the rate and amplitude of phase 0 depolarization
      1. Prolongs the Action Potential (decreases cell excitability and conduction velocity)
  3. Cardiac depressant
    1. Directly decreases the rate of phase 4, diastolic cell depolarization and automaticity
  4. Potassium Channel Blocker
    1. Prolongs QT Interval
    2. Increases refractory period
  5. Potent Anticholinergic activity
    1. May increase AV Node conduction
  • Adverse Effects
  1. Lupus Like Syndrome
  2. Hypersensitivity Reaction
  • Safety
  1. Considered safe in Lactation
  2. Pregnancy Category C
  • Metabolism
  1. Of ingested medication, 50% is hepatic metabolized and 50% is excreted unchanged
  • Dosing
  • Adult
  1. Precautions
    1. Start 6 hours after last dose of Class 1A anti-arrhythmics (e.g. Quinidine, Procainamide)
    2. Wait 6 hours before giving first XR formulation after transitioning from immediate Disopyramide
  2. Ventricular Arrhythmia
    1. Disopyramide 400 to 800 mg orally divided every 6 hours (immediate release) or 12 hours (XR)
  3. Atrial Fibrillation Rhythm Control (maintain sinus rhythm)
    1. Disopyramide 400 to 750 mg orally divided every 6 hours (immediate release) or 12 hours (XR)
  4. Renal Impairment
    1. Creatinine Clearance 40 to 60 ml/min: 400 mg/day in divided doses
    2. Creatinine Clearance 30 to 40 ml/min: 100 mg every 8 hours
    3. Creatinine Clearance 15 to 30 ml/min: 100 mg every 12 hours
    4. Creatinine Clearance <15 ml/min: 100 mg every 24 hours
  5. Other maximum dosing (use immediate release products for these conditions)
    1. Indications to limit dose to 400 mg/day in divided doses
      1. Significant liver disease
    2. Indications to limit dose to 100 mg/day divided every 6 to 8 hours
      1. Cardiomyopathy
  • Resources
  1. Disopyramide (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=11a68e26-d2e4-48f6-ba0f-9bdd5778f25a
  • References
  1. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 74-5
  2. Hamilton (2020) Tarascon Pocket Pharmacopoeia