Abstract
Slow-release aminophylline tablet (SR-AP) showed a marked tendency to dissolve slowly in the in vitro studies, dissolution rate being about 80% 9 hours after initiation of the experiment. Pharmacokinetics of theophylline was studied with 12 healthy adults. SR-AP was administered in dose of 3.01±0.44 mg/kg as theophylline and immediate-release aminophylline tablet (AP) in dose of 3.05±0.54 mg/kg. Plasma concentration of theophylline was measured by high-pressure liquid chromatography. Plasma theophylline level of SR-AP reached peak 7.7±1.4 hours after oral administration, as versus 2.0±0 hours for AP. Maximal plasma theophylline level averaged 4.34±0.92 μg/ml for SR-AP compared to 4.87±1.48 μg/ml for AP. When the serial plasma concentration data were analyzed by the one-compartment model, the mean value of the elimination rate constant (β) was 0.0742±0.0214 hr-1 for SR-AP and 0.1599±0.0214 hr-1 for AP. An average area under the curve (AUC) of SR-AP was about 2.5 times AUC of AP. It was thus suggested that SR-AP has enough potency to maintain therapeutic plasma level.
