Zarontin

Pharmacokinetics

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

Effect of liver disease

Because of the extensive liver metabolism, significant impairment of liver function may decrease the clearance of ethosuximide.

Effect of GI disease

The effects of GI disease on ethosuximide are unknown.

Adapted from: Garnett WR. Gastrointestinal and hepatic disease. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;63-74. 
With permission from Elsevier (www.elsevier.com). 

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Reviewed By: 
Steven C. Schachter, MD
on: 
Monday, March 1, 2004