Phase Function Change Effect on Drug AEDs most affected
Absorption Gastric pH Up Minimal  
Gastrointestinal motility Down Minimal  
Splanchnic blood flow Down Minimal  
Distribution Percentage of body fat Up Down All
Serum albumin Down Up (short term) PHT, VPA, CBZ
Metabolism Hepatic mass Down Up All except GP
Hepatic blood flow Down Up All except GP
Excretion Renal blood flow Down Up GP, PHB
Glomerular filtration Down Up GP, PHB

CBZ=carbamazepine; GP=gabapentin; LTG=lamotrigine; PHB=phenobarbital; PHT=phenytoin; VPA=valproate

Adapted from: Bromfield EB. Epilepsy and the elderly. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 233-254. With permission from Elsevier (

Authored By: 
EB Bromfield
Reviewed By: 
Steven C. Schachter MD
Monday, May 31, 2004