Simultaneous determination of pirprofen and its metabolite, the pyrrole derivative, in plasma by high-performance liquid chromatography.

A method for the simultaneous determination of pirprofen and its metabolite, the pyrrole derivative, in human plasma is described. The two compounds and the butyric acid analogue of the pyrrole derivative used as internal standard are extracted from plasma with chloroform, then back-extracted into an alkaline buffer. After addition of acid, the aqueous phase is assayed by high-performance liquid chromatography using a fixed-wavelength ultraviolet detector at 254 nm. The limit of quantitation is 0.1 micrograms/ml (0.396 mumol/l for pirprofen and 0.400 mumol/l for the pyrrole derivative).