Anti-epileptic drugs Flashcards
What is an epileptic seizure defined as?
‘A transient occurrence of signs and/or symptoms due to abnormal or excessive or synchronous neuronal activity in the brain’
What are the 4 phases of a seizure?
- Prodromal phase
- Aura
- Ictus
- Post-ictal phase
What occurs during the prodromal phase of a seizure?
Before the seizure begins
Animal exhibits behavioural changes such as whining and hiding
Hours to days before seizure
What behaviour can be seen from an animal in the aura phase?
Pacing, barking, salivating
Which phase is the seizure proper? What occurs in this phase?
Ictus
Involuntary muscle movements, twitches and changes in tone
What occurs in the post-ictal phase?
Consists of a period of time in which the animal may be disorientated, shows changes in appetite, thirst and toileting
1 seizure in 24 hours is called?
An isolated seizure
What is a cluster of seizures?
2 or more seizures within 24 hours
When seizures last over 5 minutes or there are multiple seizures without returning to normal this is called?
Status epilepticus
Where are epileptic seizures localised in the brain?
Forebrain
Compare a focal and a generalised seizure
Focal - specific site in the cerebrum
Generalised - involving the whole of both hemispheres
What are the signs of a focal seizure?
Motor abnormalities
Facial twitching
Unprovoked aggression
What are the signs of a generalised seizure?
Loss of consciousness
Bilateral convulsions
What is the primary cause of seizures in the brain?
Imbalance of excitation and inhibition in the neurotransmission
What is the role of AEDs?
They cannot cure seizures/epilepsy as this is not a disease in its own right
They can reduce/suppress seizure activity and reduce the progression of clinical signs
Seizures can be life-threatening
What are the 3 broad categories of MOA anti-epileptic drugs?
- Enhance the action of GABA
- Suppress the action of glutamate
- Modulate the movement of cations
What are the aims of AEDs?
- Reduce frequency of seizures
- Reduce severity of seizures
- Minimise side effects of drugs
What is classified as a response to treatment?
50% or more reduction in seizure activity
Give 4 examples of first-line AEDs
- Phenobarbital
- Potassium bromide
- Imepitoin
- Diazepam
How do first line AEDs work?
Enhances GABA induced chloride ion conductance
How is phenobarbital administered?
Orally or IV
Which first line AED is not suitable for use in cats?
Potassium bromide
How does Imepitoin act as a first line AED?
Acts as a partial agonist at the benzodiazepine site of the GABA receptor, which potentiates the action of GABA
Which of the first line AEDs reaches a steady state first?
Imepitoin
Which AED can be used for emergency treatment but not chronic management?
Diazepam
Give some examples of add-on AEDs
Gabapentin
Pregabalin
Levetiracetam
Zonisamide
What are the possible functions of Add on AEDs?
Enhance the action of GABA
Decrease glutamate release
