title: Determination of levetiracetam in human plasma/serum/saliva by liquid chromatography-electrospray tandem mass spectrometry.
abstract: BACKGROUND
  Levetiracetam (Keppra) is a novel antiepileptic drug recently approved by the U.S. Food and Drug Administration as an add-on therapy in the treatment of partial onset seizures in patients. We developed and describe a simple and rapid high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS/MS) assay for the determination of levetiracetam in human matrix (plasma, serum, or saliva).
  
  
  METHODS
  An API-3000 or API-4000 triple-quadrupole mass spectrometer (Sciex, Concord, Canada) coupled with the IonSpray source and Shimadzu HPLC system (Shimadzu Scientific Instruments, Columbia, MD) was used employing ritonavir as internal standard (IS) for levetiracetam. One hundred microliters of serum (or plasma, saliva) was deproteinized by adding 150 microl of acetonitrile containing internal standard. After centrifugation, 100 microl of supernatant was diluted with 300 microl of water and 10 microl aliquot was injected onto a C-18 column. After a 2.5 min wash the valve was activated to initiate the isocratic elution program which eluted the levetiracetam and internal standard into the MS/MS system. Quantitation by MRM analysis was performed in the positive ion mode. Within-day and between-day imprecision were evaluated for levetiracetam using three levels of in-house controls. Reliability and accuracy of this method were assessed by comparison of targets with external QC material (ChromSystems), between laboratory comparisons and by recovery studies.
  
  
  RESULTS
  Within-day coefficients of variation (CVs) were <6.1% and between-day CVs were <8.2%. The average spiked recoveries of levetiracetam added to the drug-free human plasma samples were 108% at low concentration level and 103% at high concentration level.
  
  
  CONCLUSIONS
  The method was found both specific and sensitive for the rapid and accurate measurement of levetiracetam in human matrices and correlated well with the Quest/Chantilly tandem mass spectrometric method (r=0.983).
authors.affiliation: Bioanalytical Core Laboratory, General Clinical Research Center, Georgetown University, Washington, DC, USA.
authors.forename: Tiedong
authors.initials: T
authors.lastname: Guo
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Oswald
authors.forename: Damodara Rao
authors.initials: DR
authors.lastname: Mendu
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Soldin
mesh_terms: D000927:Anticonvulsants / Q000032:analysis* / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D000077287:Levetiracetam; D010889:Piracetam / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D000927:Anticonvulsants; D000077287:Levetiracetam; D010889:Piracetam