An HPLC Method for the Determination of Theophylline and Its Metabolites in Serum and Urine

Abstract

A urine and a serum assay have been developed to quantitate theophylline and its major metabolites:1,3-dimethyluric acid, 3-methylxanthine and 1-methyluric acid. Reverse phase chromatography follows a serum acetone extraction procedure and a urine anion exchange clean-up procedure. Lower limits of sensitivity are 0.04 μg/ml for serum metabolites and 1 μg/ml for urine metabolites. Both assays are free of interference from endogenous substances. These assays have been tested successfully in pharmacokinetic and metabolic studies of theophylline.