Comparison of the QMS Analyzer With HPLC-UV for the Quantification of Lamotrigine Concentrations in Human Plasma Samples.

Background: Recently, a turbidimetric immunoassay method has been developed for use in the form of a QMS lamotrigine (LTG) commercial immunoassay. This study was designed to evaluate the performance of this immunoassay using a validated high-performance liquid chromatography-ultraviolet (HPLC-UV) method as the reference.

Methods: The performance of QMS was initially tested using drug-free plasma spiked with different amounts of LTG and, subsequently, by analyzing 61 trough plasma samples from epileptic patients given the drug as part of their maintenance antiepileptic therapies.

Results: The correlation between LTG concentrations measured by QMS and HPLC was good, with a Pearson coefficient of 0.968 (P < 0.0001). The Bland-Altman approach showed that LTG concentrations measured with QMS exceeded HPLC on an average by 15.6% (limits of agreement, -18% to +63%), with a concentration-dependent performance (mean percent bias, 49.5 ± 8.2% and 0.6 ± 12.7% for concentrations less than 2 mg/L and greater than 14.9 mg/L, respectively).

Conclusions: The QMS provided acceptable analytical performance across a wide concentration range for routine LTG measurements, being at least comparable with the other commercial immunoassays. It could be, therefore, considered as a viable alternative to HPLC methods for routine LTG monitoring in the clinical practice, although its suitability for accurate analysis of samples with low concentration is limited.