Equis ISSN 2398-2977

Phenobarbital

Synonym(s): Phenobarbitone

Contributor(s): Mark Senior

Introduction

Name

  • Phenobarbital.

Class of drug

  • Barbiturate.
  • Anti-epileptic.

Description

Chemical name

  • 5-ethyl-5-phenyl-2,4,6(1H,3H,5H)-pyrimidinetrione.
  • 5-ethyl-5-phenylbarbituric acid.

Molecular formula

  • C12H12N2O3.

Physical properties

  • Tablets.
  • Elixir.
  • Injection.

Storage requirements

  • In a dry environment.
  • <25°C.

Uses

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Indications

  • Control of seizures in suckling and weanling foals.
  • Epilepsy.

Use of phenobarbital for this indication is unauthorized in the UK.

Administration

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Pharmacokinetics

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Precautions

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Interactions

with other drugs

  • Chloramphenicol, metronidazole and progestogens - phenobarbital causes reduced plasma concentration of the interacting drug.
  • Griseofulvin - increased griseofulvin metabolism.
  • Phenytoin and sodium valproate - increased sedation.
  • Warfarin - reduced anticoagulant effect.
  • Antacids - reduced fenobarbital absorption.
  • Corticosteroids and corticotropin - increased risk of potassium loss; increased corticosteroid metabolism.
  • Phenothiazine derivatives - antagonism of the anticonvulsant effect.

Adverse Reactions

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Further Reading

Publications

Refereed papers

Other sources of information

  • Derived from The Veterinary Formulary (1998) 4th edn. Ed: Bishop Y. British Veterinary Association and Royal Pharmaceutical Society.

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