Published:Journal of Chromatographic Science,
ISSN 0021-9665 Volume
45, Number 9, October 2007, pp. 616-622
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
Elizabeth Greiner-Sosanko, Spiros Giannoutsos,
Darla R. Lower, Mohamed A. Virji, and Matthew D. Krasowski
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
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.
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