Simultaneous HPLC-F analysis of three recent antiepileptic drugs in human plasma

An original high-performance liquid chromatographic method with fluorescence detection is presented for the simultaneous determination of the three antiepileptic drugs gabapentin, vigabatrin and topiramate in human plasma. After pre-column derivatisation with dansyl chloride, the analytes were separated on a Hydro-RP column with a mobile phase composed of phosphate buffer (55%) and acetonitrile (45%) and detected at λem = 500 nm, exciting at 300 nm. An original pre-treatment procedure on biological samples, based on solid-phase extraction with MCX cartridges for gabapentin and vigabatrin, and with Plexa® cartridges for topiramate, gave high extraction yields (>91%), satisfactory precision (RSD < 6.4%) and good selectivity. Linearity was found in the 0.2–50.0 μg mL−1 range for gabapentin, in the 1.0–100.0 μg mL−1 range for vigabatrin and in the 1.0–50.0 μg mL−1 range for topiramate, with limits of detection (LODs) between 0.1 and 0.3 μg mL−1. After validation, the method was successfully applied to some plasma samples from patients undergoing therapy with one or more of these drugs. Accuracy results were satisfactory (recovery >91%). Therefore, the method seems to be suitable for the therapeutic drug monitoring (TDM) of patients treated with gabapentin, vigabatrin and topiramate.