Two sensitive and selective spectrofluorimetric and spectrophotometric methods have been developed for the determination of vigabatrin in tablets. The methods are based on derivatization with 7-chloro-4-nitrobenzofurazan (NBD-C1). The product showed an absorption maximum at 460 nm and a fluorescence emission peak at 520 nm in ethyl acetate. The color was found to be stable for at least 48 h in this solvent. The optimum conditions of the reaction were investigated and it was found that the reaction proceeds quantitatively at pH 10.0, 70 degreesC in 50 min when the mole ratio of the reagent to drug was 30. The reaction obeys Beer's law over the ranges of 2-10 and 0.05-1.00 mug ml(-1) for the spectrophotometric and spectrofluorimetric measurements, respectively. The detection limits were found to be 0.50 and 0.01 mug ml(-1) for the spectrophotometric and spectrofluorimetric methods, respectively. The proposed methods were applied to the assay of vigabatrin in tablets. The results were compared statistically with those obtained by the modified spectrofluorimetric method reported in the literature. (C) 2002 Elsevier Science B.V. All rights reserved.