Sensitive high-performance liquid chromatographic method with fluorometric detection for the simultaneous determination of gabapentin and vigabatrin in serum and urine

Serum concentrations of the antiepileptic drug gabapentin (GBP) are usually determined by high-performance liquid chromatography (HPLC) using UV photometric detection after pre-column derivatization with 2,4,6-trinitrobenzenesulphonic acid. Vigabatrin levels in serum are determined by HPLC using fluorescence detection. Like vigabatrin (VGB), gabapentin has also a primary amine group that easily reacts with o-phthaldialdehyde reagent and produces a fluorescing substance. By the use of fluorometric detection, GBP can be determined more simply, sensitively and simultaneously with VGB. The day-to-day coefficient of variation for the determination of GBP in a pooled serum was 4.0% (n=17; serum concentration, 13.8 μmol/l) and for VGB was 3.1% (n=21; serum concentration, 26.4 μmol/l). The lower limit of detection is 0.5 μmol/l for both drugs and the method is linear up to 500 μmol/l for GBP and 1300 μmol/l for VGB.