A succinimide anticonvulsant, used mainly in absence seizures.
Generic availability.
Oral agent with 93% bioavailability.
Hepatic metabolism by CYP3A4, CYP2E1 enzymes.
Half-life of 53 hours.
Excretion by renal mechanism of 20%.
The first choice drug for treating absence seizures.
Therapeutic Range: 40-100 µg/mL, with potentially toxic serum concentration: >100 µg/mL.
Available as capsules or syrup.
Affects neuronal excitability including blockage of T-type Ca2+ channels, and may effect drugs of other classes of ion channel.
Subsequent experiments on recombinant T-type channels in cell lines demonstrated conclusively that ethosuximide
Blocks all T-type Ca2+ channel isoforms.
The decrease in Na+ current is responsible for the anti-absence properties.
Valproates can either decrease or increase the levels of ethosuximide.
Combinations of valproates and ethosuximide have a greater effect than either drug alone.
It may elevate serum phenytoin levels.