Felis ISSN 2398-2950

Digoxin toxicity

Contributor(s): Barret Bulmer, Craig Devine

Introduction

  • Digoxin    Digoxin   is currently the only positive inotrope, negative chronotrope available. Its positive inotropic actions are via inhibition of the Na+/K+ ATPase and its negative chronotropic effects are via both direct and indirect sympatholytic/parasympathomimetic actions.
  • It is utilized most often in the management of systolic dysfunction, ie dilated cardiomyopathy    Heart: dilated cardiomyopathy (DCM)  , and may be used in the treatment of supraventricular arrhythmias, ie atrial fibrillation.
  • The development of more potent agents such as pimobendan   Pimobendan  , is likely to reduce reliance on this weak positive ionotrope for the support of systolic function in cats.
  • Although controversy exists over its use in additional conditions there is little debate that inappropriate or unmonitored digoxin administration may carry significant toxicity.
  • While digoxin has been utilized in the management of feline cardiovascular disease for decades, the incidence of digoxin toxicity is poorly documented. 
  • A report by Atkins et alshowed that a dose of 0.01mg/kg every 48 hours produced toxic serum levels in 50% of treated cats. This same group showed that the addition of frusemide   Furosemide  , sodium restricted diet and aspirin   Acetyl salicylic acid   predisposed normal cats to digoxin toxicity.
  • A trend toward utilizing lower doses of digoxin and careful monitoring serum digoxin concentrations will likely reduce the frequency and severity of digoxin intoxication.
    The long and very variable half-life of this drug along with its narrow therapeutic index in this species makes using digoxin in cats very difficult.

Potential toxicities

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Predisposing factors

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Treatment utilizing digoxin

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Recognition of digoxin toxicity

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Treatment of digoxin toxicity

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Further Reading

Publications

Refereed papers
  • Merrett D (2000)Digoxin therapy. Aust Vet J78(9), 612-15.
  • Rathore S S et al(2003)Association of serum digoxin concentration and outcomes in patients with heart failure. JAMA289(7), 871-878 PubMed.
  • Atkins C E et al(1990)Efficacy of digoxin for treatment of cats with dilated cardiomyopathy. JAVMA196, 1463-1469 PubMed.
  • Atkins C E et al(1989)Effects of compensated heart failure on digoxin pharmacokinetics in the cat. JAVMA195, 945-950 PubMed.
  • Atkins C E et al(1988) Effect of Aspirin, furosemide and commercial low salt diet on digoxin pharmacokinetic properties in normal cats. JAVMA193, 1264-1268 PubMed.

Other sources of information

  • Opie L H, Gersh B J (2001) Drugs for the Heart.5th edition, Philadelphia, W B Saunders. Chapter 6, pp 154-186.
  • Sisson D D & Kittleson M D (1999) Textbook of Canine and Feline Cardiology-Principles and Clinical Practice. 2nd edition, Philadelphia, W B Saunders. Chapter 12, pp 216-250.
  • Muir W W III, Sams R A, Moise N S (1999) Textbook of Canine and Feline Cardiology-Principles and Clinical Practice.2nd edition, Philadelphia, W B Saunders. Chapter 17, pp 307-330.
  • Kittleson M D, Kienle R D (1998) Small Animal Cardiovascular Medicine. St. Luis, Mosby Ltd. pp 159-166.
  • Snyder P S, Panciera D L & Volk L (1993)Digoxin pharmokinetics in dogs with experimental hypothyroidismProc Ann Vet Med Forum(Abstract).


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