Canis ISSN: 2398-2942

Phenytoin

Synonym(s): Diphenylhydantoin

Contributor(s): Kyle Braund

Introduction

Name

  • Phenytoin sodium.

Class of drug

  • Anticonvulsant

Description

Chemical name

  • 5,5-diphenyl-2,4-imidazolidinedione.

Molecular formula

  • C15H12N2O2.

Physical properties

  • Capsules.
  • Suspension.
  • Tablets.

Uses

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Indications

  • It is used to control most forms of epilepsy Epilepsy: idiopathic in human medicine.
  • Metabolized very rapidly in dogs such that very high doses need to be given often , whereas cats metabolize the drug very slowly and toxicity easily develops.
  • These undesirable pharmacokinetc properties make it a secondary agent in veterinary medicine.
  • Its use in the cat cannot be recommended.

Administration

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Pharmocokinetics

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Precautions

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Interactions

with other drugs



Many interactions are reported in the human literature. This list includes only those which may be of veterinary significance

Drugs increasing plasma concentration of phenytoin
Drugs decreasing effect of phenytoin (absorption, effects or plasma concentration)
  • Antacids.
  • Antineoplastic drugs.
  • Barbiturates.
  • Calcium.
  • Nitrofurantoin Nitrofurans
Drugs increasing plasma concentration of phenytoinDrugs decreasing effect of phenytoin (absorption, effects or plasma concentration)
  • Antacids.
  • Antineoplastic drugs.
  • Barbiturates.
  • Calcium.
  • Nitrofurantoin Nitrofurans

Adverse Reactions

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Further Reading

Publications

Other sources of information

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

ADDED