PHARMACOKINETICS OF THEOPHYLLINE METABOLITES IN 8 CHINESE PATIENTS

AIM: To study theophylline metabolites pharmacokinetics in patients af ter a therapeutic dose. METHODS: Eight adult patients with mild bronch ial asthma and normal liver function were infused aminophylline intrav enously (6.6 mu mol . kg(-1)). The plasma concentrations of theophylli ne and its 4 metabolites: 1,3-dimethyluric acid (DMUA), 3-methylxanthi ne (3-MX), 1-methyluric acid (MUA), and the intermediate 1-methylxanth ine (1-MX) were monitored by HPLC throughout 24 h. RESULTS: The plasma concentration of DMUA was the highest one among the 4 metabolites. 3- MX showed the slowest elimination rate. The plasma concentration of 1- MX throughout a 24-h period showed that there was a picking up of 1-MX (from 0.04 mu mol.L-1 to 1.05 mu mol.L-1) in the next morning. CONCLU SION: The formation of DMUA was the main metabolites. During night the re was an accumulation of 1-MX.