Table 4.5

Main mode of action of AEDs and seizure efficacy spectrum

AEDMain mode of actionBroad spectrum
CarbamazepineBlocks voltage-dependent Na+ channels (¬Na+)No
ClobazamIncreases inhibition by GABA (/GABA)No
ClonazepamIncreases inhibition by GABA (/GABA)No
EthosuximideBlocks T-type Ca2+ channels (¬Ca2+)No
GabapentinMultiple (modifies Ca2+ channels and neurotransmitter release)No
LamotrigineBlocks voltage-dependent Na+ channels (¬Na+)Yes
Levetiracetam*Novel. Binds to synaptic vesicle protein SV2AYes
OxcarbazepineBlocks voltage-dependent Na+ channels (¬Na+)No
PhenobarbitoneMultiple (¬Na+;¬Ca2+; /GABA; ¬Glutamate)Yes
PhenytoinBlocks voltage-dependent Na+ channels (¬Na+)No
TiagabineIncreases inhibition by GABA (/GABA)- potent inhibitor of GABA uptake into neurons and glial cellsNo
TopiramateMultiple (¬Na+;¬Ca2+;/GABA; ¬Glutamate)Yes
ValproateMultiple (¬Na+;¬Ca2+;/GABA; ¬Glutamate)Yes
VigabatrinIncreases inhibition by GABA (/GABA)- selective and irreversible GABA-transaminase inhibitor thus increasing whole-brain levels of GABANo
ZonisamideMultiple (¬Na+;¬Ca2+)Yes

The main mechanisms of action of the available antiepileptic drugs61 are thought to be


blockading voltage-dependent ion channels (sodium, potassium and calcium channels)


increasing the activity of the inhibitory GABA (gamma-aminobutyric acid)-ergic system and


decreasing the activity of the excitatory glutamatergic system


Levetiracetam possesses a mechanism of action distinct from that of all other AEDs.62 It has been recently shown that the synaptic vesicle protein SV2A is the binding site of levetiracetam in the brain and that levetiracetam acts by modulating the function of SV2A (figure 12.21, page 436). 62

From: Chapter 4, Principles of Therapy in Epilepsies

Cover of The Epilepsies
The Epilepsies: Seizures, Syndromes and Management.
Panayiotopoulos CP.
Oxfordshire (UK): Bladon Medical Publishing; 2005.
Copyright © 2005, Bladon Medical Publishing, an imprint of Springer Science+Business Media.

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