Anti-epileptics (year 2) Flashcards
what is epilepsy?
not a diagnosis itself, is when an animal has recurrent epileptic seizures
what is an epileptic seizure?
transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
what are the phases of an epileptic seizure?
prodromal
aura
ictus
post-ictal
what happens during the prodromal phase of an epileptic seizure and how long before the seizure does it occur?
behaviour changes hours to days before the seizure
what it the aura phase of an epileptic seizure and how long before the seizure does it occur?
first part of the seizure which includes odd behavioural with autonomic signs that occurs hours to minutes before ictus
what is the ictus phase of an epileptic seizure?
this is the seizure and is involuntary muscle movements, twitches and changes in tone
what occurs during the post-ictal phase?
various post seizure signs such as disorientation, toileting issues and neurological deficits
what are the three ways seizures may present?
isolated seizures
cluster seizures
status epilepticus
what is an isolated seizure?
1 seizure in 24 hours
what is a cluster seizure?
2 or more seizures in 24 hours
what is stats epilepticus?
seizures lasting more than 5 minutes or not returning to normal between seizures
what is always the location of a seizure in the brain?
forebrain - telencephalon or diencephalon
what does it mean if the location of the epileptic seizure is generalised?
involves the whole of both hemispheres
what is the general reason epileptic seizures occur?
imbalances of excitation and inhibition of neurotransmission in the brain due to ion channel abnormalities
what does it mean if there are increased numbers of cells in an epileptic focus of pacemaker cells?
increased seizure frequency
what is the main excitatory neurotransmitter of the brain?
glutamate
what is the main inhibitory neurotransmitter of the brain?
GABA
what is kindling?
increased epileptic activity leads to increased numbers of pacemaker cells
what can status epilepticus lead to?
hyperthermia, hypertension, acidosis, organ failure, hypoglycaemia
what does treatment of epilepsy aim to do?
reduce seizure frequency and reduce severity of seizures
when would you consider the animal to have responded to treatment?
when they have had a 50% reduction in seizure activity
what are the 3 main modes of action of anti-epileptic drugs?
enhance GABA action
reduce glutamate action
modulate ion movement
what are the three main drugs used as anti-epileptics?
potassium bromide, phenobarbital, imeptoin
what is the main mode of action of potassium bromide, phenobarbital and imeptoin?
enhance action of GABA
phenobarbital has other modes of action as well as enhancing GABA action, what are these?
reduce glutamate action and reduce calcium channel activity
how is phenobarbital administered?
oral or IV solutions
where is phenobarbital metabolised?
liver - care taken as it can cause liver damage
where is phenobarbital excreted?
some excreted unchanged in the urine
is phenobarbital protein bound?
yes highly protein bound
how is potassium bromide administered?
orally but can cause gastric irritation so give with food
what species should you not give potassium bromide?
cats - causes irreversible allergic pneumonitis
how is potassium bromide excreted?
renal excretion
how is imepitoin administered?
orally
how is imepitoin metabolised?
hepatically
how is imepitoin excreted?
as metabolites and some unchanged in faeces
what presentation of epileptic seizures is imepitoin not recommended for?
cluster
name a drug that can be used for emergency seizure treatment
diazepam
