A HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY MICROMETHOD FOR THE SIMULTANEOUS DETERMINATION OF VIGABATRIN AND GABAPENTIN IN SERUM

A gradient high-performance liquid chromatography micromethod is descr ibed for the simultaneous quantitation of vigabatrin and gabapentin in human serum. Chromatography was performed using a 125- x 3-mm ID Hype rsil BDS C-18 column with a 3-mu m mini-bore, eluted with a gradient s ystem comprised of phosphate buffer (pH 6.5)-acetonitrile-methanol-wat er at a flow rate of 0.45 ml/minute. The column eluent was monitored o n a fluorescence detector using excitation and emission wavelengths of 340 and 440 nm, respectively. The lower limit of quantitation for vig abatrin and for gabapentin was 5 mu mol/l, and the within batch and be tween-batch coefficients of variation were <5%. No interference from c ommonly prescribed antiepileptic drugs (carbamazepine and its metaboli te carbamazepine epoxide, oxcarbazepine and its metabolite 10-hydroxyi carbazepine, ethosuximide, lamotrigine, phenobarbitone, phenytoin, pri midone, and valproic acid) was observed; thus, the method can be used to monitor vigabatrin and gabapentin in patients on polytherapy antiep ileptic drug regimens.