title: Lamotrigine: single-dose pharmacokinetics and initial 1 week experience in refractory epilepsy.
abstract: Twenty-three residential patients on chronic antiepileptic drugs (AEDs) were entered into an open study of 4 weeks duration. Baseline variables and seizure frequency were determined in the first week. All patients received a single dose of lamotrigine in the second week to determine single-dose pharmacokinetic parameters. Twenty patients then received daily or twice daily lamotrigine for a week. Post-treatment seizure frequency was observed for a further week. Patients taking liver enzyme inducing antiepileptic drugs showed a mean lamotrigine plasma elimination half-life (T1/2) of 14 h (+/- 7) (T1/2 of normal volunteers = 24 h) and those taking sodium valproate and an inducing AED showed a mean lamotrigine T1/2 of 30 h (+/- 10). The plasma concentrations of co-administered sodium valproate, phenytoin, carbamazepine, phenobarbitone and primidone were not altered by 1 week lamotrigine dosing. There was a significant reduction in complex partial seizures in the treatment week compared with baseline. Some patients showed a marked increase in seizure frequency on stopping lamotrigine. There was an increase in reports of drowsiness during lamotrigine administration, but there were no clinically significant changes in any safety measure.
mesh_terms: D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000493:pharmacokinetics* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004361:Drug Tolerance; D004827:Epilepsy / Q000188:drug therapy / Q000378:metabolism*; D005260:Female; D006801:Humans; D000077213:Lamotrigine; D008297:Male; D008875:Middle Aged; D014227:Triazines / Q000493:pharmacokinetics* / Q000627:therapeutic use
chemical_list: D000927:Anticonvulsants; D014227:Triazines; D000077213:Lamotrigine