OBJECTIVE To investigate the absorption kinetics of scutellarin-PEG conjugates at different intestine segments of rats and
the influence of different concentration and molecular weight of the drugs on the intestinal absorption after PEGylation.METHODS The intestine in rats was cannulated for in situ recirulation.RESULTS The
absorption rate constant(K_a) at duodenum,jejunum and ileum were 0.132 6,0.079 9,0.081 9 h~(-1),
respectively.The K_a of scutellarin at the concentrations of 30,100 and 200 mg·L~(-1) in intestine were 0.029 2,0.033 8,0.030 6 h~(-1) while the K_a of scutellarin-PEG400 conjugates at the concentrations of 40,130 and 260 mg·L~(-1) were 0.157 7,0.162 4 and 0.170 8 h~(-1),respectively.The K_a of scutellarin and its PEG200,400,1000 conjugates were 0.033 8,0.154 7,0.162 4 and 0.068 0 h~(-1),respectively.CONCLUSION The PEGylation enhances the absorption of scutellarin in rat intestine.However,among the PEG conjugates,with the increased PEG molecular weight,the absorption of conjugates decreases accordingly.The conjugates are well absorbed at the duodenum in rats.The concentration has no effect on the absorption kinetics.The absorption of scutellarin and its conjugates are a first-order process with the passive diffusion mechanism.