LC procedure with SPE for quantification of indobufen enantiomers: pharmacokinetic studies

A rapid and selective liquid chromatography (LC) with solid phase extraction (SPE) to quantify indobufen (INDB) enantiomers is described. The INDB enantiomers and internal standard (racemic flurbiprofen) are extracted from a small volume of acidified serum (0.2 ml) by means of SPE using cartridges with octadecyl chemically bound phase and analysed on reversed phase (RP), C18 column with ultraviolet detection at 275 nm. Recovery of both INDB enantiomers was in the range 92.1-94.3%. The mobile phase is composed of acetonitrile-potassium dihydrogen phosphate (pH 4.75; 10 mM) (38:62, v/v). The linear range of the standards curves was from 0.25 to 25.00 microg ml(-1) in serum for both enantiomers. The limit of quantification and detection for both INDB enantiomers in serum were 0.25 microg ml(-1) (CV < or = 10%), and 0.1 microg ml(-1), respectively. Both intra- and inter-day accuracy and precision of the calibration curves were determined and their CV values did not exceed 10%. The validated method has been successfully applied for chiral pharmacokinetics studies of INDB from tablets and intramuscular injections in man.