Felis ISSN 2398-2950

Warfarin

Synonym(s): Coumadin

Contributor(s): Mark Rishniw

Introduction

Name

  • Warfarin.

Class of drug

  • Vitamin K antagonist.
  • Indirect anticoagulant.

Description

Chemical name

  • 3-(alpha-acetonylbenzyl)-4-hydroxycoumarin.

Molecular formula

  • C19H15NaO4.

Physical properties

  • Racemic mix of S-warfarin and R-warfarin.

Storage requirements

  • In light-resistant containers.
  • At room temperature.
  • Powder for injection should be used immediately after reconstituting.

Uses

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Indications

Thromboembolic disorders
  • These may be seen as part of several disorders including glomerulonephritis and feline myocardial disease.

Administration

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Pharmocokinetics

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Precautions

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Interactions

with other drugs

  • Warfarin is highly protein bound and therefore its activity may increase if serum protein levels drop or drugs which are themselves protein-bound are administered concomitantly. In particular, the following apply:

Drugs enhancing the anticoagulant effect of warfarin

Drugs reducing the anticoagulant effect of warfarin

  • Spironolactone.
  • Barbiturates including primidone   Primidone  .
  • Corticosteroids.
  • Griseofulvin   Griseofulvin  .

with diagnostic tests

  • International normalized ratio is 2-3.
  • PIVKA.

Adverse Reactions

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Further Reading

Publications

Refereed papers

  • Smith S Aet al(2000)Pharmacodynamics of warfarin in cats.J Vet Pharmacol Ther23(6), 329-337.
  • Smith S Aet al(2000)Pharmacodynamics of warfarin in cats.J Vet Pharmacol Ther23(6), 339-344.

Other sources of information

  • Based onSmall Animal Formulary.Tennant, Bryn (1999) 3rd edn. Cheltenham: BSAVA.

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