Liquid chromatography tandem mass spectrometry method for the estimation of lamotrigine in human plasma: Application to a pharmacokinetic study

Abstract

A reliable, selective and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for the quantification of lamotrigine in human plasma using lamotrigine-¹³C3, d3 as an internal standard. Analyte and internal standard were extracted from human plasma by solid-phase extraction and detected in positive ion mode by tandem mass spectrometry with electrospray ionization (ESI) interface. Chromatographic separation was performed on a Chromolith^® SpeedROD; RP-18e column (50-4.6 mm i.d.) using acetonitrile: 5±0.1 mM ammonium formate solution (90:10, v/v) as the mobile phase at a flow rate of 0.500 mL/min. The calibration curves were linear over the range of 5.02-1226.47 ng/mL with the lower limit of quantitation validated at 5.02 ng/mL. The analytes were found stable in human plasma through three freeze (-20 °C)-thaw (ice-cold water bath) cycles and under storage on bench-top in ice-cold water bath for at least 6.8 h, and also in the mobile phase at 10 °C for at least 57 h. The method has shown good reproducibility, as the intra- and inter-day precisions were within 3.0%, while the accuracies were within ±6.0% of nominal values. The validated LC-MS/MS method was applied for the evaluation of pharmacokinetic and bioequivalence parameters of lamotrigine after an oral administration of 50 mg lamotrigine tablet to thirty-two healthy adult male volunteers.

Keywords: Lamotrigine; Liquid chromatography/tandem mass spectrometry; Pharmacokinetic study; Solid phase extraction.

Fig. 1

Chemical structure of lamotrigine and lamotrigine-¹³C3, d3.

Fig. 2

The product ion spectra of lamotrigine (A) and lamotrigine-¹³C3, d3 (B).

Fig. 3

Representative chromatograms in human plasma: (A) double plasma blank; (B) plasma blank with ISTD; (C) LLOQ, 5.02 ng/mL; and (D) ULOQ 1226.47 ng/mL. Lamotrigine (left panels, A–D) and its ISTD–lamotrigine-¹³C3, d3 (right panels, A–D).

Fig. 4

The linear mean plasma concentration versus time profile of lamotrigine in plasma.