[Development and validation of a new HPLC method for determination of Lamotrigine and clinical application]

Lamotrigine is an effective anticonvulsant drug used in the treatment of epilepsy. It has a narrow therapeutic range, a large inter and intra-individual pharmacokinetic variability and some concentration-dependent side effects.

The aim of this study was to develop and validate a new method for lamotrigine quantitation in plasma using HPLC with UV/visible detection.

A rapid HPLC-UV method was developed for the determination of lamotrigine in plasma. All solvents used were HPLC grade.

After liquid-liquid extraction, chromatographic separation was achieved using an RP 18 (250 mm) column. The mobile phase was composed of acetonitrile and 0.1 M potassium dihyrogenophosphate (25/75) (v/v). Barbital sodium was used as internal standard. This technique was linear over the 2 μg/mL to 50 μg/mL range (r= 0.99). Detection and quantification limits were 0.07 μg/mL and 0.21 μg/mL, respectively. Within-day coefficient of variation (13.37 to 16 %) and day-to-day coefficients of variation (15.68 to 16.63 %) at three different concentrations. Under these conditions, each analysis required no longer than 10 min. We finally evaluated the plasma concentrations of lamotrigine in Tunisian patients treated with this drug.

The results found are similar to those previously described and the developed method is repeatable and reproducible. It can be used for clinical applications.