title: Drug monitoring: simultaneous analysis of lamotrigine, oxcarbazepine, 10-hydroxycarbazepine, and zonisamide by HPLC-UV and a rapid GC method using a nitrogen-phosphorus detector for levetiracetam.
abstract: A high-performance liquid chromatography (HPLC) assay using UV detection is described for the simultaneous measurement of the newer generation anti-epileptic medications lamotrigine, oxcarbazepine (parent drug and active metabolite 10- hydroxycarbazepine), and zonisamide. Detection of all four compounds can be done at 230 nm; however, there is a potential interference with zonisamide in patients on clonazepam therapy. Therefore, the method uses dual wavelength detection: 230 nm for oxcarbazepine and 10-hydroxycarbazepine and 270 nm for lamotrigine and zonisamide. In addition, a simple gas chromatography method using a nitrogen-phosphorus detector is described for the measurement of levetiracetam, another of the recently approved anti-epileptic medications. For both methods, limits of quantitation, linearities, accuracies, and imprecisions cover the therapeutic range for drug monitoring of patients. A wide variety of clinical drugs, including other anti-epileptic drugs, do not interfere with these assays. These procedures would be of special interest to clinical laboratories, particularly due to the limited availability of immunoassays for newer generation anti-epileptic medications and that therapeutic uses of these drugs are expanding beyond epilepsy to other neurologic and psychiatric disorders.
authors.affiliation: Toxicology and Therapeutic Drug Monitoring Laboratory, Division of Clinical Chemistry, Department of Pathology, University of Pittsburgh Medical Center, Children's Hospital Main Tower 5812, Pittsburgh, PA 15213, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Greiner-Sosanko
authors.forename: Spiros
authors.initials: S
authors.lastname: Giannoutsos
authors.forename: Darla R
authors.initials: DR
authors.lastname: Lower
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Virji
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Krasowski
mesh_terms: D000927:Anticonvulsants / Q000097:blood*; D002220:Carbamazepine / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood; D002849:Chromatography, Gas / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D007555:Isoxazoles / Q000097:blood*; D000077213:Lamotrigine; D000077287:Levetiracetam; D009584:Nitrogen / Q000032:analysis; D000078330:Oxcarbazepine; D010758:Phosphorus / Q000032:analysis; D010889:Piracetam / Q000031:analogs & derivatives* / Q000097:blood; D015203:Reproducibility of Results; D014227:Triazines / Q000097:blood*; D014466:Ultraviolet Rays; D000078305:Zonisamide
chemical_list: C039775:10,11-dihydro-10-hydroxycarbamazepine; D000927:Anticonvulsants; D007555:Isoxazoles; D014227:Triazines; D010758:Phosphorus; D002220:Carbamazepine; D000077287:Levetiracetam; D000078305:Zonisamide; D009584:Nitrogen; D000077213:Lamotrigine; D000078330:Oxcarbazepine; D010889:Piracetam