Absorption of ethosuximide is more complete and faster from the syrup than from the capsule dosage form. Ethosuximide is extensively distributed throughout the body but is not bound to plasma proteins.
There is no first-pass metabolism but the drug is extensively metabolized in the liver to inactive metabolites.19 CYP3A4 is the main isoenzyme involved in the metabolism of ethosuximide, although CYP2E also has an important role and CYP2B may be involved.20-21
Because of the extensive liver metabolism, significant impairment of liver function may decrease the clearance of ethosuximide.
The effects of GI disease on ethosuximide are unknown.
Reviewed March 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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