Solid-phase extraction of piribedil and its metabolites from plasma and urine without and after deconjugation, by high performance liquid chromatography.

A new high performance liquid chromatographic procedure has been developed for the simultaneous quantification of piribedil (PD) and its three main basic metabolites in rat plasma and urine, without and after hydrolysis. The procedure relies on isolation of the compounds from plasma and urine constituents using the Sep-Pak C18 cartridge, with satisfactory recovery and specificity, and resolution by acetonitrile gradient elution on a C18 reversed phase column coupled to a UV detector monitored at 240 nm. The assay was linear over a wide range of concentrations for all compounds in both body fluids with mean within-day and day-to-day coefficient of variation (CV) and relative error (RE) generally below 10%. Plasma concentrations of PD and its metabolites at selected intervals and urinary recoveries of all compounds before and after enzymatic hydrolysis are presented.