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A. Causes [2]

  1. Most commonly due to elevated levels of digoxin in serum
    1. Drug overdose
    2. Drug interactions
    3. Precipitated by hypokalemia
    4. Progressive renal failure
  2. Ingestion of Digitalis or Related Cardiac Glycosides
    1. Foxglove plant (Digitalis purpurea)
    2. Wooly foxglove (Digitalis lanata)
    3. Ornamental oleander (Nerium oleander)
    4. Yellow oleander (Thevetia peruviana)
    5. Squill or sea onion (Uriginea maritima)
    6. Lily of the valley (Convallaria majalis)
    7. Ouabain (Strophanthus gratus)
    8. Determine serum digitoxin levels (rather than digoxin)
  3. Cardiac glycosides from skin of certain toads (found in some herbal remedies)

B. Symptoms

  1. Anorexia, Nausea, Vomiting, Diarrhea
  2. Blurred vision
    1. Color distortion
    2. Yellow halo around lights
    3. Photophobia
  3. Cardiac Conduction Anomalies
    1. Cardiac glycosides increase vasal (parasympathetic) activity
    2. Atrioventricular block
    3. Slow sinus rate (sinus bradycardia)
    4. Extrasystole (atrial and ventricular)
    5. Usually responds transiently to atropine
  4. Malignant Arrhythmias

C. Drug Interactions Affecting Digoxin Levels [3]

  1. Increases Digoxin Levels
    1. Quinidine
    2. Amiodarone
    3. Erythromycin
    4. Propafenone
    5. Verapamil
    6. Spironolactone
  2. Decreases Digoxin Levels
    1. Sulfasalazine
    2. Cholestyramine
    3. Antacids

D. Treatment

  1. Supportive care
  2. Stop digoxin
  3. Reduce Absorption
    1. Charcoal may be useful since digoxin undergoes significant enterohepatic recirculation
    2. Cholestyramine
  4. Maintain Serum K+ >4.5mEq (hypokalemia can precipitate severe arrhythmias)
  5. Normalize serum Na+, Mg2+
  6. Phenytoin (dilantin) or lidocaine may be used to treat arrhythmias
  7. Dixogin specific Fab fragments (see below)
  8. Dialysis is generally not helpful due to high volume of distribution

E. Indications for Anti-Digoxin Fab' Fragments (Digibind®) [4,5]

  1. Shock or Cardiac Arrest or Ventricular Tachycardia
  2. AV Block or Sinus Bradycardia unresponsive to atropine
  3. Digoxin Level >10ng/mL or ingestion of >10mg digoxin
  4. Hyperkalemia with any other signs of digoxin toxicity
  5. Impaired clearance of drug in renal failure - lower threshold for use of Fab'
  6. May also be effective for treatment of ingestion of yellow oleander [6]

References

  1. Brunner G, Zweiker R, Krejs GJ. 2000. Lancet. 356(9239):1406 (Case Report) abstract
  2. Newman LS, Feinberg MW, LeWine HE. 2004. NEJM. 351(6):594 (Case Discussion) abstract
  3. Krisanda TJ. 1992. Postgrad Med. 91(6):273 abstract
  4. Ujhelyi MR, Robert S, Cummings DM, et al. 1993. Ann Intern Med. 119(4):273 abstract
  5. Digibind. 1986. Med Let. 28(722):87
  6. Eddleston M, Rajapakse S, Jayaleth RS, et al. 2000. Lancet. 355(9208):967 abstract