Determination of proquazone and its m-hydroxy metabolite by high-performance liquid chromatography. Clinical application: pharmacokinetics of proquazone in children with juvenile rheumatoid arthritis.

A method for the determination of proquazone and its m-hydroxy metabolite in serum and urine by reversed-phase high-performance liquid chromatography is described. The technique is based on a single extraction of the unchanged drug, its metabolite and an internal standard from serum or urine with chloroform. The column was packed with mu Bondapak C18 and the mobile phase was acetonitrile--water (50:50) (pH 3). The detection limits for proquazone and its metabolite were 0.02 mumol/l using 500 microliters of sample. For the determination of the total m-hydroxy metabolite only 100 microliters of sample are needed. The method described is suitable for routine clinical and pharmacokinetic studies. The clinical application of this method suggests that the pharmacokinetics of proquazone in adults and children are similar.