Bovis ISSN 2398-2993

Phenylbutazone

Synonym(s): Bute

Contributor(s): Vetstream Ltd, Louise Cox-O’Shea , Andrea Tarr

Introduction

Name

  • Phenylbutazone.
Prohibited for use in food producing animals!

Class of drug

  • Non-steroidal anti-inflammatory drug (NSAID).

Description

Chemical name

  • 4-butyl-1,2-diphenyl-pyrazolidine-3,5-dione.

Molecular formula

  • C19H20N2O2.

Molecular weight

  • 308.374 g/mol.

Physical properties

  • Lipophilic.

Storage requirements

  • Room temperature.

Uses

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Indications

  • Inflammation, pain and pyrexia.
Prohibited for use in food producing animals!Can cause severe toxic reactions and fatal life threatening blood dyscrasias!

Administration

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Pharmocokinetics

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Precautions

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Interactions

With other drugs

  • Phenylbutazone is extensively bound to plasma proteins; it may displace other drugs that are highly protein-bound, or it may itself be displaced to produce an increase in non-bound pharmacologically active concentrations which can lead to toxic effects.
  • Concurrent therapy with other therapeutic agents should be undertaken with caution due to the risk of metabolic interactions.
    • There is evidence to indicate that the pharmacokinetics of penicillin and gentamicin products may be affected by concurrent administration of products containing phenylbutazone with a possible reduction of therapeutic efficacy, since tissue penetration may be reduced.
  • The distribution of other drugs given concurrently may also be affected.
  • Phenylbutazone induces hepatic microsomal enzyme activity.
  • Concurrent use of other NSAIDs or corticosteroids increases the risk of gastrointestinal adverse effects Anti-inflammatory drugs: overview.

Drugs that may affect phenylbutazone

  • Barbiturates -may affect metabolism.
  • Cardiac glycosides - may increase metabolism and decrease effect.
  • Chloramphenicol - decreased metabolism.
  • Colestyramine - decreased enteral absorption.
  • Corticosteroids, other NSAIDs and sulfonamides - displacement from plasma proteins and increased effect.​

Drugs that may be affected by phenylbutazone

  • Methotrexate - decreased excretion.
  • Penicillins- altered half-life and tissue penetration.
  • Phenytoin - decreased metabolism.
  • Sulfonylureas - increased hypoglycemic effect.
  • Levothyroxine - falsely low plasma-total levothyroxine.
  • Warfarin - increased anticoagulant effect.

Withdrawal Period

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Adverse Reactions

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Anderson D E, Edmondson M A (2013) Prevention and Management of Surgical Pain in Cattle. Vet Clin North Am Food Anim Pract 29(1),157-184 PubMed.
  • Authie E C et al(2010) Effect of an endurance-like exercise on the disposition and detection time of phenylbutazone and dexamethasone in the horse: Application to medication control. Equine Vet J 42(3), 240-247 PubMed.
  • Sabate D, Homedes J, Salichs M, Sust M & Monreal L (2009) Multicentre, controlled, randomised and blinded field study comparing efficacy of suxibuzone and phenylbutazone in lame horses. Equine Vet J 41(7), 700-705 PubMed.
  • Conwell R & Stratford C (2008) Right dorsal colitis. Vet Rec 13(8), 7-10.
  • Lees P Maitho T E, Ayliffe T, Taylor J B O (1988) Pharmacokinetics, metabolism and excretion of phenylbutazone in cattle following intravenous, intramuscular and oral administration. Res Vet Sci  44(1), 57-67 PubMed.
  • Eberhardson B, Olsson G, Appelgren L, Jacobsson S O (1979) Pharmacokinetic studies of phenylbutazone in cattle. J Vet Pharm Therap 2(1), 31-37.

Other sources of information

  • Plumb's Veterinary Drug Handbook.
  • Food and Drug Administration. DEPARTMENT OF HEALTH AND HUMAN SERVICES. (2003) New Animal Drugs; Phenylbutazone; Extralabel Animal Drug Use; Order of Prohibition.
  • Derived fromThe Veterinary Formulary. 4th edn (1998) Bishop, Y (Ed.). British Veterinary Association and Royal Pharmaceutical Society.

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