Measurement of progabide and its deaminated metabolite in plasma by high-performance liquid chromatography and electrochemical detection.

Progabide (4- [[(4-chlorophenyl-5-fluoro-2-hydroxyphenol)-methylene] amino] butanamide) and its deaminated metabolite were measured simultaneously in plasma by high-performance liquid chromatography. Both compounds were extracted from plasma and the molecules were stabilized at the methylene--amino double bond with sodium borohydride reduction. Oxidative electrochemical detection was used for final quantitation. The method was used to measure progabide and progabide acid in plasma from a healthy volunteer who received a single 1200-mg dose of progabide orally. Lower limits of detection for progabide and progabide acid were 30 and 15 ng/ml, respectively. Coefficient of variation was less than 5% for both compounds.