Retrospective Analysis of Pediatric and Adult Populations Using an LC-MS/MS Method for Oxcarbazepine/Eslicarbazepine Metabolite.

BACKGROUND: Therapeutic drug monitoring of anti-epileptic drugs is important to manage seizure control in patients with epilepsy. Oxcarbazepine is a second-generation anti-epileptic drug approved for use in pediatric patients, and eslicarbazepine acetate is a newer generation drug used as adjunctive therapy and monotherapy for partial-onset (focal) seizures. While several second and third generation anti-epileptic drugs have broader therapeutic efficacy in patients, these drugs can still have severe side effects and variable interpatient pharmacokinetics. Consequently, there is a need for accurate and sensitive analytical methods to support therapeutic drug monitoring. METHODS: An assay improvement for a LC-MS/MS method was developed for the major metabolite of oxcarbazepine and eslicarbazepine, licarbazepine (MHD), using a 13C-labeled form of the compound as the internal standard. Additionally, retrospective data analysis was used to compare the distribution of results observed in adult vs pediatric patients. RESULTS: Accuracy and linearity across the analytical measuring range of 1 to 60 µg/mL was acceptable. Inter- and intra-run precision was less than 6% at 3 concentrations tested. The limit of detection was determined to be 0.5 µg/mL. Significant interference from hemolysis, icterus, lipemia, or 187 other potential interferences was not detected. CONCLUSIONS: The improved assay for MHD was appropriate for clinical use. Retrospective data analysis showed that pediatric and adult patients had a similar distribution of oxcarbazepine/eslicarbazepine metabolite concentrations in serum.