The objective of this communication is to describe the changes in the metab
olic profile of valproic acid (VPA) from early to late childhood and adoles
cence. A cross-sectional study of 12 children and adolescents attending a n
eurological outpatients department, who were medicated with VPA, was carrie
d out. The proportions of daily dose excreted as VPA-glucuronide 3-oxo-VPA
and 4-OH-VPA were calculated by relating 24-h recovery of these metabolites
from urine to daily VPA dose. VPA, 3-oxo-VPA and 2-en-valproic acid (2-en-
VPA) were measured in trough serum samples. VPA and its metabolites were me
asured using a capillary gas chromatography method. The proportion of daily
dose recovered as VPA-glucuronide in children 10 years and younger was sma
ller than in older children (p < 0.05). There were no differences between a
ge groups in the recovery of the other measured metabolites. Lamotrigine (L
TG) comedication was also associated with a higher proportion of VPA dose r
ecovered as glucuronide (p < 0.01). LTG comedication had a stronger associa
tion with a higher proportion of dose being recovered as VPA-glucuronide on
multivariate analysis than did the age group (p = 0.001 versus p < 0.05).
In conclusion, older children and adolescents, when compared with younger c
hildren, and those comedicated with LTG excrete a higher proportion of VPA
dose as VPA-glucuronide. Copyright (C) 2000 John Wiley & Sons, Ltd.