Gabapentin is rapidly absorbed, reaching a peak in 2 to 4 hours. It binds to a leucine-amino acid protein in the gut and is actively absorbed. The bioavailability of gabapentin decreases with increase in dose. It is not metabolized, is not bound to plasma proteins, and is excreted unchanged in the urine.32

Effect of liver disease

Liver disease should not affect gabapentin because it is not hepatically metabolized and is not protein-bound.

Effect of GI disease

It is unknown whether GI disease affects the leucine-amino protein that is responsible for the active absorption of gabapentin.

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 (

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