Objective: To explore the absorption kinetics and absorption mechanisms of cinobufagin in the gastrointestine of rats

and to provide a basis for the development of cinobufagin. Method: The absorption kinetics were obtained by using the in situ perfusion method in rat. The concentration was determinated using HPLC method. Result: After 3 hours perfusion

cinobufagin in different concentrations (11

22

33 mg·L-1) can be better absorpted both in the stomach and small intestine

and the cumulative uptake was 75%. The absorption kinetics were independent of the concentration of the drug. Absorption in the small intestine showed obvious first-order kinetics characteristics

and absorption rate constant of three concentrations was 0.548

0.547

0.590 h-1

respectively. Cinobufagin was absorbed in all segments of intestine

and it showed a first-order process with passive diffusion mechanism. The absorption rate constant in the duodenum

jejunum

ileum

and colon were 0.024 6

0.015 2

0.016 4

0.013 5 cm-1·h-1

respectively. Conclusion: Cinobufagin was absorbed in the stomach and all segments of intestine of rats

and its absorption kinetics was a first-order process with passive diffusion mechanism.