Theophylline is well and rapidly absorbed when taken as a plain tablet or as a liquid solution but the rate and extent of absorption from sustained-release formulation may be affected by several factors. Because host factors related to gastrointestinal physiology impose highly variable theophylline absorption profile on systasined-release formulation, the probability of malabsorption must be considered in dosage recommendations for some patients. The present study is designed to investigate the effects of age, gender, obesity on the absorption of theophylline from a sustained-release formulation. The follow-up sheets were reviewed retrospectively for 1019 patients who had a serum theophylline determination at SNUH from 1990 to 1994. thirty-two subjects, aged 21-83 year, were selected according to our inclusion criteria. They all have stable disease state treated with theophylline and no major organ failure or gastrointestinal lesion. Current smokers were excluded. On each occasion oral theophylline in a sustained-release formulation was taken before or after Ⅳ aminophylline is administrated. The difference in apparent clearance companying with change of administration route was calculated and when the difference(CLPO-CLIV) is more than 10% of CLIV, grouped to malabsorption group. Excepts for change in administration route, all conditions maintained constant and so malabsorption is only factor contributing to apparent clearance increasements.
Total twenty patients(62.5%) were classed to malabsorption group and mean difference of CL of malabsorption group was 25.3% of CLIV. There were no obesity-associated difference in theophylline absorption and males tend to have larger difference than females(65% vs 53%). In both gender, when they were grouped according to age, Clearance change were not significantly(P=0.0577) different.
|