Table 2.

Population parameters of the final pharmacokinetic model of the three antiepileptic drugs of the study: (a) levetiracetam, (b) lamotrigine, and (c) valproic acid.

A. Levetiracetam
	Parameter	SE	RSE (%)	p Value
Fixed effects
Ka	2.6	–	–
V	25.01	5.65	22.6
beta_V_logBW	1	–	–	<0.001
Cl	1.51	0.27	18.1
beta_Cl_logBW	0.75	–	–	<0.001
Between-subject variabilities
omega_V	0.84	0.16	19.1
omega_Cl	0.59	0.10	17.2
Correlations
corr_V_Cl	0.86	0.18	21.4
Residual error parameters
a	3.82	0.96	25.0
B. Lamotrigine
	Parameter	SE	RSE (%)	p-value
Fixed effects
Ka	1.57	–	–
V	5.15	1.18	22.9
beta_V_logBW	2.83	0.52	18.4	<0.001
Cl	0.15	0.02	13.3
beta_Cl_DailyDose	0.0056	0.0007	13.0	<0.001
beta_Cl_Regimen	–0.61	–0.13	22.2	<0.001
Between-subject variabilities
omega_V	0.32	0.07	23.4
omega_Cl	0.28	0.07	22.7
Residual error parameters
b	0.15	0.03	19.8
C. Valproic acid
	Parameter	SE	RSE(%)	p-Value
Fixed effects
Ka	1.68
V	15.61	4.84	31.0
beta_V_Age	0.07	0.016	23.3	0.032
beta_V_logBW	1	–	–	<0.001
Cl	0.12	0.013	10.4
beta_Cl_VA	0.0012	0.0001	9.7	<0.001
Between-subject variabilities
omega_V	0.33	0.081	24.5
omega_Cl	0.089	0.024	26.7
Residual error parameters
b	0.14	0.037	27.1

a, the constant component of the residual error model; b, the proportional component of the residual error model; beta_Cl_DailyDose, factor for the relationship between Cl and lamotrigine daily dose; beta_Cl_logBW, allometric exponent for the relationship between body weight and Cl; beta_Cl_Regimen, factor for the relationship between Cl and therapeutic regimen (whether existence of valproic acid); beta_V_Age, factor for the relationship between age and volume of distribution; beta_V_logBW, allometric exponent for the relationship between body weight and V; BW, body weight; Cl, clearance; corr_V_Cl, correlation coefficient between V and Cl; F, bioavailability fraction; omega_Cl, between-subject variability for Cl; omega_V, between-subject variability for V; V, volume of distribution.