| Mechanism of Action of Antiseizure Drugs | • Enhancement of GABAergic
(inhibitory) transmission
• Diminution of excitatory (usually
glutamatergic) transmission
• Modification of ionic conductances |
| Mechanism of Action PHENYTOIN | • alters Na+, K+ and Ca2+ conductance, membrane potentials, and the concentrations of amino acids and the
neurotransmitters norepinephrine, acetylcholine, and GABA
• blocks sustained high-frequency repetitive firing of action potentials
• Inhibits calcium influx across the cell membrane (inhibits glutamate release, enhances GABA release) |
| Mechanism of Action CARBAMAZEPINE | • blocks high frequency firing of
neurons through action on VG
Na+ channels
• decreases synaptic release of
glutamate |
| Mechanism of Action PHENOBARBITAL | • enhancement of inhibitory processes
and diminution of excitatory
transmission
• binds to an allosteric site on the
GABAA receptor, and enhances the
GABA-receptor mediated current by
prolonging the openings of the
chloride channels |
| Mechanism of Action PRIMIDONE | similar to phenytoin but converted
to phenobarbital |
