[Study on absorption mechanism of genistein self-microemulsifying system in rat intestines].

OBJECTIVE

To investigate the absorption mechanism of genistein self-microemulsifying system in rat intestines.

METHOD

The concentrations of phenol red and genistein by in situ perfusion in rats were determined by UV and HPLC, respectively. The effects of drug concentrations, pH, various intestinal segments and P-glycoprotein (P-gp) inhibitor verapamil on the absorption had been studied.

RESULT

The absorption rate constant (Ka) of genistein had no significant difference at concentrations of 0.05-0.5 mg x mL(-1) and pH of 5.4-7.8 in perfusion. It was Ka of jejunum > ileum > duodenum > colon. The absorption of genistein in jejunum had significant difference (P < 0.05) compared with other parts of intestines. Ka was increased obviously when verapamil was coper-fused with genistein (P < 0. 05).

CONCLUSION

The absorption of genistein self-microemulsifying system is a first order process with passive diffusion mechanism related to P-gp efflux. It can be absorbed at all segments of rat intestine, and the jejunum is the best absorption segment, pH had no special effect on the absorption of genistein self-microemulsifying system in rat intestine.