Simultaneous assay of felbamate plus carbamazepine, phenytoin, and their metabolites by liquid chromatography with mobile phase optimization

Rory P. Remmel, Scott A. Miller, Nina M. Graves

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

Felbamate is an investigational antiepileptic drug (AED) in clinical trials. A high-performance liquid chromatographic method for the simultaneous analysis of felbamate, phenytoin (PHT), 5-(p-hydroxyphenyl)-5-phenylhydantoin, carbamazepine (CBZ), carbamazepine-10,11-epoxide, and carbamazepine-10,11-diol in serum was developed by a mobile phase optimization technique. Capacity factors for the compounds of interest and 12 other AEDs and metabolites were determined with mixtures of methanol, acetonitrile, or tetrahydrofuran and a 0.01 M ammonium phosphate buffer, pH 6.5, on a reversed-phase C8 column. An optimized mobile phase composition was determined that could separate the compounds of interest and three internal standards in <15 min. Serum was extracted with CH2Cl2/ethyl acetate (2:1) after addition of three internal standards. The method was validated for within-day and between-day precision and accuracy for the six compounds. Coefficients of variation were generally <10% at all concentrations and <5% in the typical therapeutic range for each compound. The lower limit of detection was estimated at 0.2 µg/ml for CBZ and its metabolites and 0.5 µg/ml for felbamate and PHT. For felbamate, the lowest point on the standard curve was 1.88 µg/ml with a between-day variability of 10.3%. The assay was used to determine the serum concentrations of PHT and CBZ and its metabolites in a subject before, during, and after felbamate therapy.

Original languageEnglish (US)
Pages (from-to)90-96
Number of pages7
JournalTherapeutic drug monitoring
Volume12
Issue number1
DOIs
StatePublished - Jan 1990

Keywords

  • Analysis
  • Carbamazepine
  • Felbamate
  • High-performance liquid chromatography
  • Optimization
  • Phenytoin

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