Abstract
Measurement of the serum level of theophylline (TP) is essential for its appropriate use.It has been reported that the metabolic capacity of individual patients can be estimated from simultaneously measuring the serum levels of TP and these metabolites.In this study,we measured the serum TP and metabolite levels in patients treated with 2 types of sustainedrelease TP preparation,and investigated the influence of the pharmacokinetics of TP by employing different forms.
The subjects were asthma patients who visited the outpatient clinic of Respiratory Medicine,St.Luke’s International Hospital,between April and October 2003,and were medicated with sustained-release TP tablets (Theodur® or Uniphyl® tablets).Blood samples were collected from patients who gave written consent.They were also interviewed and their medical records were investigated to confirm their backgrounds.The serum TP and metabolite levels were measured by HPLC.
In 52 patients treated with Theodur® tablets,there was a strong correlation between the serum TP and 1,3-dimethyluric acid (DMU) levels (r=0.670).However,there was a weak correlation in 30 patients treated with Uniphyl® tablets (r= 0.249).In the two groups,the DMU/TP was within the range of the mean±SD regardless of blood collection points in all patients.The values markedly differed from this range in patients with factors influencing TP metabolism.
The results suggest that,in patients receiving Theodur® tablets,their TP-metabolizing capacity can be predicted by simultaneously measuring the serum TP and metabolite levels and calculating the DMU/TP.However,such a prediction is difficult in those receiving Uniphyl® tablets.
