Anti-Epileptic Drugs Flashcards
Name the classes of anti-epileptic drugs
Na channel blockers
GABA potentiators
Ca channel blockers
GABA-transaminase inhibitors
Increased GABA production drugs
Levetiracetam
Name some Na channel blockers
Carbamazepine - partial
Phenytoin - status epilepticus and generalised
Lamotrigine - partial
Sodium valproate - generalised
Name some Ca channel blockers
Ethosuximide - absence
Sodium valproate - absence
Name some GABA potentiators
Barbiturates - phenobarbital - generalised
Benzodiazepines - midazolam - generalised
Benzodiazepines - lorazepam - acute treatment of seizures
Name some GABA-transaminase inhibitors
Vigabatrin
Name some increased GABA production drugs
Gabapentin
How does levetiracetam act to control epilepsy
Levetiracetam binds to synaptic vesicles to inhibit pre-synaptic Ca channel activity and prevent neurotransmitter release from pre-synaptic neurone to prevent an action potential from starting in the post-synpatic neurone
When should anti-epileptics be considered
If there is an unprovoked seizure as well as:
- Neurological deficit
- EEG shows unequivocal epileptic activity
- Risk of further seizure
- Imaging reveals structural abnormality
If an AED cannot be tolerated by a patient, how would you change the drug to a new one
Keep the old drug on while a new drug is started at initial dose
Slowly increase new drug until it reaches middle of recommened therapeutic range
Once in the middle, can slowly withdrawl old drug
Name some adverse effects of AEDs
Dizziness, fatigue, ataxia, diplopia
Levetiracetam - irritability, behaviour change
Gabapentin - irritability, behaviour change, weight gain
Topiramate - weight loss, anorexia, metabolic acidosis, language dysfunction
Sodium valporate - weight gain
Carbamazepine - weight gain
Lamotrigine - tics, insomnia
Are teratogenic -> careful during pregnancy
What teratogenic effects does sodium valproate have on a foetus and what can be done to try and prevent this
Sodium valproate causes decreased serum folate resultling in neural tube defects, craniofacial and skeletal abnormalities
Also causes developmental disorders after birth
Must start folate tablets before pregnancy to try and prevent this
Only used if no other alternative though must counsel on risks and contraception
Which patients have an increased risk of seizure if taken off their AED
Patients with epilepsy during childhood
Patients on >1 AED
Myoclonic or tonic-clonic seizures
Abnormal EEG within the year
Known underlying brain damage
When should cessation of AEDs be thought about and how should an AED be taken off
Cessation fo AEDs can be considered if patient is seizure free for at least 2yrs
Must gradually taper off AEDs to avoid recurrent seizures and avoid anxiety/restlessness
If >1 drug then withdraw one at a time with a month in between removing the next
Describe phenytoin, its therapeutic window and when it is given
Phenytoin is an anticonvulsant and cardiac depressant - can be given as additional agent to stop a seizure
Has a narrow therapeutic window -> requires therapeutic drug monitoring
Give loading dose -> drug -> check after few hours, then a few days and then every 3-12mths
Name some adverse effects of phenytoin
Nausea
CNS dysfunction - confusion, nystagmus, ataxia
Decreased consciousness
Coma
Congential malformations, e.g. cleft lip/palate, congenital heart defects
