Block 6 - AED drugs and anesthetics Flashcards
What is the MOA of gabapentin/pregabalin?
Block the alpha-2-delta subunit of P/Q-type calcium channels on the presynaptic membrane
this blocks the influx of calcium and prevents glutamate release
What is the MOA of phenytoin?
What other drugs have the same MOA?
blocks voltage gated sodium channels on the presynaptic membrane, preventing depolarization.
Carbamazepine
Oxcarbazepine
Fosphenytoin
What is the MOA of levetiracetam?
blocks the exocytosis machinery involved in glutamate release (SV2A inhibitor)
What is the MOA of felbamate?
NMDA receptor blocker
What is the MOA of perampanel?
AMPA receptor blocker
What is the MOA of retigabine?
Enhances the effects of Girk channels (KCNQ potassium channels), thereby hyperpolarizing the membrane on both the pre-synaptic and post-synaptic cell membranes
class 1b anti-rhythmic agents can be used to treat…
- partial seizures: sequester aberrant focal point neurons (carbamazepine and phenytoin)
- tonic-clonic (general) seizures: both used
- status epilepticus: phenytoin IV used at relatively large doses to sequester the AP propagations, particularly when GABA failure occurs from loss of chloride gradient
What are the side effects of class 1b anti-rhythmic agents?
nausea, headache, interactions with CYP
Give an example of a broad-spectrum cation channel blocker and explain how it works.
What is it typically used for?
What major risk is associated with it?
Lamictal (lamotrigine)
Blocks sodium channels, but not in the same manner as class 1b. It also blocks some calcium channels.
Tonic-clonic seizures (and others to a lesser extent)
Stevens-Johnson syndrome is a risk
Other than seizures, what can sodium channel blocker AEDs be used for?
Bipolar disorder
What are KCNQ enhancers used for? What is the major side effect?
Give an example of a KCNQ enhancer
Partial seizures
Retinal deformity and loss of visual acuity
Retigabine (ezogabine)
Where do voltage gated calcium channel regulatory subunit blockers bind?
On the alpha-2-delta-2 subunit, even though the site of action is the alpha-2-delta-1 subunit
Describe the mechanism of action of neurontin and lyrica. What are they used to treat?
They bind at the alpha-2-delta-2 subunit of axonal calcium channels on glutamate neurons and block the alpha-2-delta-1 subunit (no calcium influx)
they’re used to treat partial seizures, but they’re not first line
they can also be used for pain treatment
Where does keppra (levetiracetam) bind?
How does it work (MOA)?
Selectively binds to SV2A (a synaptic vesicle integral membrane protein)
It blocks glutamate release
Keppra is used to treat…
What are its side effects?
Partial seizures
Tonic/Clonic seizures
Status epilepticus
Side effect - sleepiness
Give an example of a drug that works as an AMPA channel blocker. What kind of antagonist is it?
Perampanel
Noncompetitive antagonist