Differential cognitive effects of carbamazepine and gabapentin.
OBJECTIVE
The cognitive effects of the newer antiepileptic drugs (AEDs) compared with the older standard AEDs are uncertain.


METHODS
We directly compared the cognitive effects of carbamazepine (CBZ) and gabapentin (GBP) in 35 healthy subjects by using a double-blind, randomized crossover design with two 5-week treatment periods. During each treatment condition, subjects received either GBP, 2,400 mg/day, or CBZ (mean, 731 mg/day) adjusted to a dose to achieve midrange standard therapeutic blood levels (mean, 8.3 microg/ml). Subjects were tested at the end of each AED treatment period and in four drug-free conditions [two pretreatment baselines and two post-treatment washout periods (1 month after each AED)]. The neuropsychological test battery included 17 measures yielding 31 total variables.


RESULTS
Direct comparison of the two AEDs revealed significantly better performance on eight variables for GBP, but none for CBZ. Comparison of CBZ and GBP to the nondrug average revealed significant statistical differences for 15 (48%) of 31 the variables. Pairwise follow-up analyses of the 15 variables revealed significantly better performance for nondrug average on 13 variables compared with CBZ, and on four compared with GBP. GBP was better than nondrug average on one variable.


CONCLUSIONS
Although both CBZ and GBP produced some effects, GBP produced significantly fewer untoward cognitive effects compared with CBZ at the dosages used in this study.
Meador
K J
KJ
Department of Neurology, Medical College of Georgia, Augusta 30912, USA. KMEADOR@NEURO.MCG.EDU
Loring
D W
DW
Ray
P G
PG
Murro
A M
AM
King
D W
DW
Nichols
M E
ME
Deer
E M
EM
Goff
W T
WT
D000085:Acetates / Q000494:pharmacology* / Q000627:therapeutic use; D000293:Adolescent; D000328:Adult; D000588:Amines; D000927:Anticonvulsants / Q000494:pharmacology* / Q000627:therapeutic use; D001288:Attention / Q000187:drug effects; D002220:Carbamazepine / Q000494:pharmacology* / Q000627:therapeutic use; D003071:Cognition / Q000187:drug effects*; D018592:Cross-Over Studies; D003509:Cyclohexanecarboxylic Acids; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004569:Electroencephalography / Q000187:drug effects / Q000706:statistics & numerical data; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D000077206:Gabapentin; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D000927:Anticonvulsants; D003509:Cyclohexanecarboxylic Acids; D002220:Carbamazepine; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin