Drugs for Epilepsy

Question 1

Lamotrigine

Answer 1

• voltage gated sodium channel blocker
• only work when channel is in open or fast-inactivated state
• neurons in epileptic state are more often in open state, and bind sodium channel blockers better
• decreases excitation

Question 2

carbamazepine

Answer 2

• voltage gated sodium channel blocker
• only work when channel is in open or fast-inactivated state
• neurons in epileptic state are more often in open state, and bind sodium channel blockers better
• decreases excitation

Question 3

phenytoin

Answer 3

• voltage gated sodium channel blocker
• only work when channel is in open or fast-inactivated state
• neurons in epileptic state are more often in open state, and bind sodium channel blockers better
• zero order kinetics, risk of toxicity!
• CYP450 inducer, and gingival hyperplasia
• decreases excitation

Question 4

topiramate

Answer 4

• voltage gated sodium channel blocker AND AMPA receptor blocker AND GABA-A receptor agonist
• only work when channel is in open or fast-inactivated state
• neurons in epileptic state are more often in open state, and bind sodium channel blockers better
• decreases excitation

Question 5

valproic acid

Answer 5

• voltage gated sodium channel blocker
• AND enhances Glutamic Acid Decarboxylase to produce more GABA
• AND inhibits SSD from metabolizing GABA
• only work when channel is in open or fast-inactivated state
• neurons in epileptic state are more often in open state, and bind sodium channel blockers better
• decreases excitation AND increases inhibition

Question 6

lacosamide (zonisamide/rufinamide)

Answer 6

• voltage gated sodium channel blocker
• works during both the fast inactivated and slow inactivated
• (zonisamide is also a T-type Ca blocker)
• decreases excitation

Question 7

perampanel

Answer 7

• AMPA receptor blocker on post-synaptic cell

- decreases excitation

Question 8

felbamate

Answer 8

• NMDA receptor blocker on post-synaptic cell

- decreases excitation

Question 9

ethosuxamide

Answer 9

• T-type Ca channel blocker
• only used for absence/petit mal seizures
• decreases excitation

Question 10

levetiracetam

Answer 10

• inhibit SV2A vesicle protein
• prevents release of glutamate by preventing fusion of the vesicle
• decreases excitation

Question 11

brivaracetam

Answer 11

• inhibit SV2A vesicle protein
• prevents release of glutamate by preventing fusion of the vesicle
• decreases excitation

Question 12

gabapentin

Answer 12

• blocks α2δ subunit of the T-type Ca channel
• AND enhances Glutamic Acid Decarboxylase to produce more GABA
• decreases excitation AND increases inhibition

Question 13

pregabalin

Answer 13

• blocks α2δ subunit of the T-type Ca channel
• AND enhances Glutamic Acid Decarboxylase to produce more GABA
• decreases excitation AND increases inhibition

Question 14

ezogabine

Answer 14

• OPENS K+ channel on both pre and post synaptic neurons
• makes K+ leave cells, polarizing them
• at high doses, it can also act as a post-synaptic GABA receptor agonist
• decreases excitation

Question 15

tiagabine

Answer 15

• blocks GAT1 on pre-synaptic GABAergic neurons
• prevents reuptake of GABA
• increases inhibition by GABA

Question 16

vigabatrin

Answer 16

• inhibits GABA-T enzyme in pre-synaptic neurons
• prevents the breakdown of GABA
• risk of bilateral concentric vision loss, D/C after 3 months. must complete training course to Rx
• increases inhibition by GABA

Question 17

lorazepam
diazepam
clobazam
clonazepam

Answer 17

• bind to allosteric site on Cl- channel WITH GABA to potentiate effect
• increases inhibition

Question 18

barbiturates

Answer 18

• GABA independent
• bind to allosteric site on Cl- channel WITHOUT GABA to potentiate effect
• increases inhibition

Question 19

cannabidiol

Answer 19

• does not appear to bind to CBD receptors

- used specifically for Dravet syndrome and Lennox-Gastaut syndrome

Question 20

patient presents with status epilepticus:

Answer 20

1. give lorazepam

2. give levetiracetam