Determination of Pimethixene in Plasma and Urine by High Performance Liquid Chromatography

A high performance liquid chromatographic (HPLC) assay was developed for the determination of pimethixene in plasma and urine. Pimethixene was extracted by a rapid and simple liquid-liquid procedure using n-pentane:isopropyl alcohol (50:1), and a reversed phase HPLC separation technique with UV spectrophotometric detection at 254 nm. Determination was possible for pimethixene in the concentration range 53-530 ng ml with the limit of detection at 20 ng/ml for both plasma and urine. The overall recoveries of pimethixene added to plasma and urine samples by an external standard method were 95.6 and 98.5%, with coefficients of variation of 0.9993 and 0.9997, respectively.