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Pharmacokinetics of theophylline metabolites in 8 Chinese patients
Aim:
To study theophylline metabolites pharmacokinetics in patients after a therapeutic dose.
Methods:
Eight adult patients with mild bronchial asthma and normal liver function were infused aminophylline intravenously (6.6 mumol.kg-1). The plasma concentrations of theophylline and its 4 metabolites: 1,3-dimethyluric acid (DMUA), 3-methylxanthine (3-MX), 1-methyluric acid (MUA), and the intermediate 1-methylxanthine (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 mumol.L-1 to 1.05 mumol.L-1) in the next morning.
Conclusion:
The formation of DMUA was the main metabolites. During night there was an accumulation of 1-MX.