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Cardiac glycosides

Last updated: October 23, 2020

Summary

Cardiac glycosides are drugs that inhibit the Na+/K+- ATPase found on the outer cell surface. Digoxin is the only drug of this class that is commonly used in clinical settings. The main indications for digoxin treatment are atrial fibrillation and heart failure in treatment-resistant cases. Because cardiac glycosides have a narrow therapeutic index, close monitoring of serum concentrations is necessary. Typical symptoms of cardiac glycoside poisoning are nausea, vomiting, blurry vision, and cardiac arrhythmias. Overdose can quickly become life-threatening and swift treatment is vital. The first-line treatment for cardiac glycoside poisoning is administration of digoxin-specific antibodies.

Overview

  • Drugs: digoxin, ouabain
  • Mechanism: inhibition of the cardiac and neuronal Na+/K+- ATPase
  • Onset of effect
    • Oral: 0.5–2 h
    • IV: 15–30 min
  • Half-life: 36–40 hours
  • Protein binding: 20–40%
  • Elimination: renal

References:[1][2][3][4]

Pharmacodynamics

Cardiac glycosides inhibit Na+/K+-ATPase, increasing cardiac contractility and decreasing AV conduction and heart rate!

Cardiac glycoside poisoning

Etiology

Clinical features

Diagnostics

Treatment

Digoxin has a narrow therapeutic index! Serum concentrations of cardiac glycosides must be monitored closely because overdoses can have severe consequences!

You better visit a hospital directly!”: Yellow blurry vision and halos are the signs of digoxin poisoning.

References:[2][4]

Indications

References:[3][5]

Contraindications

References:[5]

We list the most important contraindications. The selection is not exhaustive.

Interactions

References

  1. Katzung B,Trevor A. Basic and Clinical Pharmacology. McGraw-Hill Education ; 2014
  2. Levine M, O'Connor A, Traub SJ, Burns MM, Grayzel J. Digitalis (Cardiac Glycoside) Poisoning. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/digitalis-cardiac-glycoside-poisoning.Last updated: February 7, 2017. Accessed: July 21, 2017.
  3. Giardina E-G, Sylvia L, Olshansky B, Downey BC. Treatment with Digoxin: Initial Dosing, Monitoring, and Dose Modification. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-with-digoxin-initial-dosing-monitoring-and-dose-modification.Last updated: June 8, 2017. Accessed: July 21, 2017.
  4. Goldberger AL, Traub SJ, Downey BC. Cardiac Arrhythmias due to Digoxin Toxicity. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/cardiac-arrhythmias-due-to-digoxin-toxicity.Last updated: August 28, 2015. Accessed: July 21, 2017.
  5. UpToDate. Digoxin: Drug Information. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/digoxin-drug-information.Last updated: January 1, 2017. Accessed: July 21, 2017.
  6. Le T, Bhushan V, Sochat M, Petersen M, Micevic G, Kallianos K. First Aid for the USMLE Step 1 2014. McGraw-Hill Medical ; 2014
  7. WebMD. Digoxin (Rx). Digoxin (Rx). New York, NY: WebMD. http://reference.medscape.com/drug/lanoxin-digoxin-342432. Updated: July 1, 2016. Accessed: July 21, 2017.
  8. WebMD. Digitek (Digoxin Tablets) Drug. Digitek (Digoxin Tablets) Drug. New York, NY: WebMD. http://www.rxlist.com/digitek-drug.htm#medguide. Updated: February 23, 2017. Accessed: July 21, 2017.
  9. Patel V. Digitalis Toxicity. In: Rottman JN, Digitalis Toxicity. New York, NY: WebMD. https://emedicine.medscape.com/article/154336. Updated: January 4, 2017. Accessed: May 15, 2018.