INFLUENCE OF CONCURRENT ANTIEPILEPTIC MEDICATION ON THE PHARMACOKINETICS OF LAMOTRIGINE AS ADD-ON THERAPY IN EPILEPTIC CHILDREN

1 Lamotrigine is a new antiepileptic drug, chemically unrelated to cur rently used antiepileptic medication. Its pharmacokinetics can be infl uenced by concomitant antiepileptic medication. 2 This study was perfo rmed to assess the pharmacokinetic profile of lamotrigine in three gro ups of children treated with different types of comedication: drugs kn own to induce, to inhibit or to have no clinically significant influen ce on drug metabolism, respectively. 3 Thirty-one children aged 6 mont hs to 5 years were included and received a 2 mg kg(-1) single oral dos e. Lamotrigine plasma profiles were different between the three comedi cation groups. The half-lives (mean+/-s.d.) were: 7.7+/-1.8 h, 21.9+/- 6.8 h, 44.7+/-10.2 h in the 'inducer', 'other' and 'inhibitor' groups respectively. 4 Patients were then dosed to steady state, with the dos age adjusted on the basis of the single dose pharmacokinetics to achie ve a minimum plasma concentration between 1.5 and 3 mg l(-1). The mean minimum plasma concentration for the three groups was 2.54+/-1.28 mg l(-1) at steady state. 5 Dosage of lamotrigine can be optimised with k nowledge of the metabolic effects of antiepileptic comedication.