Pharmacokinetics of lamotrigine in paediatric and young adult epileptic patients--nonlinear mixed effects modelling approach.
OBJECTIVE
The purpose of the study was to examine and describe adjunctive lamotrigine (LTG) pharmacokinetics in paediatric and young adult patients using a nonlinear mixed effects modelling (NONMEM) approach.


METHODS
The study included 53 patients (age range 3-35 years) who were concomitantly treated with carbamazepine (CBZ) and/or valproic acid (VPA). A total of 70 blood samples corresponding to trough levels were available for analysis. Data were modelled, and the final model was evaluated using NONMEM and auxiliary software tools.


RESULTS
The final LTG population model included the effects of concomitant drugs and patient's weight (WT) which stratified the population into three groups: ≤25 kg, >25 to <60 kg and ≥60 kg. Based on the final model, the estimated LTG oral clearance (CL/F) for a typical patient weighing ≤25 kg, >25 to <60 kg or ≥60 kg who was concomitantly treated with CBZ was estimated to be 3.28, 4.23, or 7.15 l/h, respectively. If a patient was concomitantly treated with CBZ + VPA, the CL/F decreased on average by 69.5 % relative to LTG + CBZ co-therapy. VPA was found to decrease the LTG CL/F by 87.6 % compared to co-therapy with only CBZ.


CONCLUSIONS
The LTG population pharmacokinetic model developed in this study may be a reliable method for individualising the LTG dosing regimen in paediatric and young adult patients on combination therapy during therapeutic drug monitoring.
Medicines and Medical Devices Agency of Serbia, Belgrade, Serbia.
Branka
B
Brzaković
Katarina
K
Vučićević
Sandra Vezmar
SV
Kovačević
Branislava
B
Miljković
Milica
M
Prostran
Žarko
Ž
Martinović
Milena
M
Pokrajac
D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000097:blood / Q000493:pharmacokinetics*; D002220:Carbamazepine / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004347:Drug Interactions; D016903:Drug Monitoring; D004827:Epilepsy / Q000378:metabolism*; D005260:Female; D006801:Humans; D000077213:Lamotrigine; D008297:Male; D008954:Models, Biological; D017711:Nonlinear Dynamics; D014227:Triazines / Q000097:blood / Q000493:pharmacokinetics*; D014635:Valproic Acid / Q000627:therapeutic use; D055815:Young Adult
D000927:Anticonvulsants; D014227:Triazines; D002220:Carbamazepine; D014635:Valproic Acid; D000077213:Lamotrigine