Epilepsy Flashcards
What is epilepsy
seizures due to an unregulated neuronal discharge in the brain
What are the types of seizures
Remain in 1 place
-Focal seizures
-Localised structural abnormality
Waves of activity spread from the focal centre
-generalised seizures
-Chain reactions of depolarisations and synaptic activity
Seizure symptoms dependent on area affected - focal v generalised
Aura
What causes seizures
Imbalance between inhibitory (GABA) and excitatory activity (Glutamate)
Neurones in focal area sudden depolarizations
what Ca2 channel do absence seizures involve
T-type voltage-gated Ca2+channels
What mechanisms are targeted for drugs for epilepsy
Enhanced GABA transmission
Inhibition of Na+ channels
Inhibition of Ca2+ channels
What can inhibiting GABA cause
excitatory pathways = seizures!
What is GABAa
Ligand gated ion channel
What antiepileptic drugs can work at the GABAa channel
Modulatory site- benzos and barbituates
- they potentiate the opening of the channel (open time and increase Cl going in, increasing effects) eg
- clobazepam lorazepam
- barbituates also enhance hyperpolarization enhancing effect of GABA eg: phenobarbital
What drugs change GABA metabolism
Vigabatrin- GABA transaminase inhibitor which usually breaks down GABA to glutamate. Blocks therefore more GABA available for use
Valproate- increases no. of GABA in brain
What drugs inhibit GABA reuptake
Tiagabine is a GABA reuptake (GAT1) inhibitor
Therefore increases no. of GABA following synaptic release
What drugs act at voltage gated Na channels
Blocks action potentials from ongoing
eg:
valproate
phenytoin
carbamazepine
lamotrigine
Use-dependant= works at cells that are repetitively firing
Block inactivated site of voltage gated Na channels. Therefore slows recovery.
What drugs work at (inhibit) voltage gated Ca2+ channels
Ttype ca channel blockers for ansence seizures
-ethosuxamide
-valproate
Gabapentin can also help as decreases activity of P/Q type Ca2+
Where does levetiracetam bind
Synaptic vesicle protein SV2A
Drugs that inhibit glutamate receptors
phenobarbital
Topiramate (blocks AMPA receptors)
Perampanel
