MEASUREMENT OF URINARY METABOLITES OF THEOPHYLLINE AND SERUM THEOPHYLLINE LEVEL WITH ASTHMATIC CHILDREN

Abstract

The examination of urinary theophylline and theophylline metabolism were studied in 7 asthmatic children. High-pressure liquid chromatography was devised to quantitate theophylline metabolites in the 24-hr urine of 5 patients and in the time course of 2 patients who had been receiving 20mg/kg of theophylline orally in a day. Mean values for the theophylline-derived urine products were unchanged theophylline 15.3±4.07, 3-methylxanthine 14.0±1.86, 1, 3-dimethyluric acid 38.9±6.62, and 1-methyluric acid 31.8±6.65 (%). Metabolites were exprssed as internal standard equivalents on a molar basis. There was a direct correlation between urinary 3-methylxanthine and 1-methyluric acid and a inverse correlation between 1, 3-dimethyluric acid and 1-methyluric acid+3-methylxanthine, 1, 3-dimethyluric acid and 1-methyluric acid, unchanged theophylline and 1-methyluric acid+1, 3-dimethyluric acid, unchanged theophylline and 3-methylxanthine in urine, respectively. In the case of 2 patients in time course measurerent, the urine content of theophylline and 1-methyluric acid+1, 3-dimethyluric acid were inversely related. The urinary unchanged theophylline and 3-methylxanthine were also inversely related. There were some relations between the concentration of urinary unchanged theophylline and those of serum theophylline. This might reflect the capacity in theophylline metabolism because it was different among patients. From this we suggest it would be useful to determine the most appropriate administration of theophylline.