Determination of Phenylbutazone and Its Metabolites in Plasma by Gas-Liquid Chromatographic Procedure

Abstract

A gas-liquid chromatographic (GLC) method is described for the determination of phenylbutazone and its metabolites, oxyphenbutazone and γ-hydroxyphenylbutazone, in human or rabbit plasma following administration of phenylbutazone. A modified Herrmann's extraction method has been used and coupled with the GLC procedure without derivative formation ation for phenylbutazone and using trimethylsilylation for the metabolites. This method is accurate and sufficiently sensitive for use in routine clinical assay and the estimation of pharmacokinetic parameters of phenylbutazone and its metabolites. The utility of the procedure was corroborated by its application to the determination of phenylbutazone and its metabolites in the plasma samples obtained from rabbits and patients chronically treated with phenylbutazone.