Canis ISSN: 2398-2942

Therapeutics: anti-epileptics

Synonym(s): Anti-convulsants

Contributor(s): Kyle Braund, Lauren Trepanier

Anti-epileptics

Drugs to control epilepsy

  • Treatment should not follow a single seizure unless status epilepticus develops: investigation for underlying cause must precede diagnosis of idiopathic epilepsy Epilepsy: idiopathic.
  • Partial seizures more difficult to control than generalized, but no drug specifically indicated for either condition.
  • Aim to suppress seizures by maintaining effective concentration of drug in the brain, minimizing side-effects.
  • Drugs are mainly lipid soluble, distributed readily to all tissues so plasma levels reflect tissue concentrations.
  • Most drugs are liver enzyme inducers → enhance metabolism of themselves and other drugs.
  • Monitor patient regularly for hepatotoxicity with phenobarbital by checking bile acids every 6-12 months, withdrawal should always be gradual.
  • Phenobarbital Phenobarbital - drug of choice for canine epilepsy. Some neurologists use potassium bromide as a first line agentEpilepsy drug table.
  • Imepitoin Imepitoin - may have fewer side effects than phenobarbital.
  • Primidone Primidone. More hepatotoxic than Phenobarbital; not recommended.
  • Phenytoin sodium Phenytoin. Not useful in dogs due to short half-life.
  • Potassium bromidePotassium bromide.
  • Sodium valproateSodium valproate.
  • Zonisamide Zonisamide useful for refractory epilepsy in dogs.
  • Topiramate - can be used in combination with standard anticonvulsants in refractory cases.

Drugs for status epilepticus

  • Repeated seizures without periods of consciousness → emergency requiring prompt treatment or → brain damage and death.
  • If cause unknown, administer diazepamDiazepam or midazolamMidazolam both of which cross blood-brain barrier quickly.
  • Solvent (painful on IM injection) and oil-in-water preparations (painful and irritant on IV injection)
  • Alternatives are pentobarbitone sodium Pentobarbital , and phenobarbitone sodium Phenobarbital.

Further Reading

Publications

Refereed Papers

  • Recent references from VetMed Resource and PubMed.
  • Packer R M, Shihab N K, Torres B B, Volk H A (2015) Responses to successive anti-epileptic drugs in canine idiopathic epilepsy. Vet Rec 176 (8), 203 PubMed.
  • Podell M, Rusbridge C, Stein V, Tipold A, Volk H A (2015) International veterinary epilepsy task force consensus proposal: outcome of therapeutic interventions in canine and feline epilspy.  BMC Vet Res 11, 177 PubMed.
  • Peters R K, Schubert T, Clemmons R, Vickroy T (2014) Levetiracetam rectal administration in healthy dogs.  JVIM 28 (2), 504-509 PubMed.
  • Dewey C W  et al (2004) Zonisamide therapy for refractory idiopathic epilepsy in dogs.  JAAHA 40(4) 285-291 PubMed.

Other sources of information

  • Plumb D C (1999) Veterinary Drug Handbook. 3rd edn. Iowa State University Press, Ames Iowa.


ADDED