title: Levetiracetam in children with refractory epilepsy: lack of correlation between plasma concentration and efficacy.
abstract: OBJECTIVE
  The goals of this study are to evaluate the efficacy and tolerability of levetiracetam (LEV) as add-on therapy in children with refractory epilepsies and to determine the value of LEV blood level monitoring in this population.
  
  
  METHODS
  Sixty-nine children (39 males and 30 females) treated with LEV between 2006 and 2007 were selected. Their medical files were reviewed for LEV efficacy and tolerability. In a subgroup of children currently taking LEV, plasma concentrations were determined by high performance liquid chromatography by ultraviolet detection (HPLC-UV) method and correlated with the given dose per kilo as well as clinical response.
  
  
  RESULTS
  Fifty-one patients (74%) had a more than 50% reduction in seizure frequency with 16 patients (23%) becoming seizure free on LEV. Eighteen (26%) patients had a less than 50% reduction in seizure frequency. Adverse events due to LEV ranged from mild to moderate in only 18 patients (26%). The most frequently observed were drowsiness, behavioral difficulties, increase in seizure frequency and headaches. The majority (60.5%) of the responders received doses between 10 and 50mg/kg/day and had a plasma concentration (PC) between 5 and 40microg/ml. However, we found no clear correlation between PC and efficacy.
  
  
  CONCLUSIONS
  Levetiracetam given twice a day in children with refractory epilepsy reduces seizure frequency in all types of epilepsy. In children, LEV is a broad spectrum anticonvulsant with a favourable safety profile.
authors: Department of Physiology, University of Montreal, C.P. 6128, succursale Centre-ville, Montréal, Québec, Canada. patricia.giroux@umontreal.ca
authors: Patricia C
authors: PC
authors: Giroux
authors: Milagros
authors: M
authors: Salas-Prato
authors: Yves
authors: Y
authors: Théorêt
authors: Lionel
authors: L
authors: Carmant
mesh_terms: D000293:Adolescent; D000927:Anticonvulsants / Q000378:metabolism / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004827:Epilepsy / Q000097:blood* / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D000077287:Levetiracetam; D008297:Male; D010889:Piracetam / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics / Q000627:therapeutic use; D012189:Retrospective Studies; D055502:Secondary Prevention; D016896:Treatment Outcome
chemical_list: D000927:Anticonvulsants; D000077287:Levetiracetam; D010889:Piracetam