Lec 44 Antiepileptic Drugs Flashcards
(57 cards)
What are the main types of seizures?
- partial = begin locally
- –> simple
- –> complex
- –> sexondarily generalized
- generalized with or without convulsions
- –> absence
- –> myoclonic
- –> tonic
- –> clonic
- –> tonic-clonic
- –> atonic
What is use of narrow-spectrum anti-epileptic drugs?
- effective in partial seizures [including secondarily generalized]
- less effective in primary generalized tonic-clonic seizures
- not useful for myoclonic or absence
What is use of broad spectrum anti-epileptic drugs?
- effective in partial
- effective in generalized [primary or secondary]
use narrow-spectrum or broad spectrum drugs for myoclonic or absence seizures?
broad spectrum!!! narrow spectrum not useful and may even worsen
Why are some particular brain regions more likely to become epileptic foci?
- because of intrinsic burst firing or automaticity characteristics of the cell types
- because of close packing of neurons in sheets
What are some anti-epileptic drugs that inhibit Na channels?
- carbamazepine
- lamotrigine
- phenytoin
- topiramate
- valproate
What is first line drug of choice for simple focal seizure?
carbamazepine
What is first line drug of choice for complex focal seizure?
carbamazepine
What are the 3 first line options for generalized tonic-clonic seizure?
- phenytoin
- carbamazepine
- valproic acid
phrase for remembering the 4 broad spectrum anti-epileptics we need to learn?
Lamb values a top clone
- lamotrigine
- valproate
- topiramate
- clonazepam
What is the first line for absence seizures?
ethosuximide
What is the first line of acute vs prophylaxis status epilepticus?
prophylaxis = phenytoin acute = benzodiazepines
Which Na channels are likely to be inhibited first by AEDs?
preferentially inhibit channels that are open with high freq/burst firing
What is mech of action of benzodiazepines?
- increase activity of GABA-A receptors
What is mech of phenobarbital [barbiturate]?
- increase activity of GABA-A receptors
What is mech of topiramate?
blocks NA channels AND increases GABA-A receptor action
What is mech of action tiagabine?
increases synaptic levels of GABA by blocking GABA reuptake
What is mech of action gabapentin?
- may increase release of GABA
- may also inhibit high voltage activated Ca channels or Na channels
What is function of T-type Ca channels? what type of epilepsy are they associated wtih?
- exist in thalamocortical neurons and involved in generating sleep spindles
excess firing through T-type Ca leads to absence seizure
Which 4 types of drugs can be used to treat absence epilepsy?
- ethosuximide = first line
- valproate
- lamotrigine
- clonazepam = less used
What drug inhibits N/P type Ca channels?
lamotrigine
When do you start treatment for status epilepticus? What is initial treatment?
treat ASAP to protect against neuronal damage
initial = benzodiazepine [lorazepam, etc] PLUS fosphenytoin or phenytoin to prevent recurrence
What are refractory treatments for status epilepticus if cannot be controlled with standard benzo + phenytoin?
- give phenobarbital or valporate IV
- if not controlled in 1 hr, give general anesthesia
What is induction of elimination?
if drug A increases expression of enzyme –> drug B is eliminated at higher rate
