Abstract: AIM: To develop a HPLC-UV method to determine the concentration of riluzole in human plasma and study its bioequivalence.METHODS: Single oral dose (150 mg)of riluzole (national procted and import) was given to 20 healthy male volunteers in a randomized cross-over study. Riluzole was extracted from plasma by solid-phase extraction and assaved by a validated highperformance liquid chromatography (HPLC)method with UV detection. Plasma samples (1. 0 ml) applied to a 1 ml C18 solid phase columns. The columns were washed sequentially with distilled water (1ml), and 30 %(volume/volume)methanol. The samples were eluted with 1 ml methanol and dried under a stream of nitrogen. The samples were applied to the HPLC in little methanol. Riluzole was isolated then and detected by UV absorption of 265 nm.Variance analysis and two-one sided test statistical analysis were performed for pharmacokinetic parameters.RESULTS: The main pharmacokinetic parameters of riluzole (the national procted and import)were as follows: C_max: 930 ±321 μg·L^-1 and 798 ±306 μg·L^-1; t_max: 0. 8 ±0. 5 and 1. 2 ±0. 7 h; AUC_{0 ～ t} 3361 ±890 μg·h^-1 ·L^-1 and 3301 ±886 μg·h^-1 ·L^-1; AUC_{0 ～ ∞}: 661 ±886 μg·h^-1·L^-1 and 3615 ±885 μg·h^-1·L^-1; t_1/2:8. 2 ±2. 8 and 8. 1 ±2. 6 h. The relative bioavailability of AUC_{0～ 36} was (102. 8 ± 15. 5)%.CONCLESION: The two formulations were bioequivalent.

Key words: solid-phaseextraction, HPLC, bioequivalence, pharmacokinetics