[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.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Beijing University of Chinese Medicine, Beijing 100029, China.
Xian-hua
XH
Du
Xin
X
Niu
Qian-jin
QJ
Feng
Hong
H
Du
Hai-yan
HY
Li
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000037:antagonists & inhibitors; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004655:Emulsions; D019833:Genistein / Q000032:analysis / Q000378:metabolism* / Q000493:pharmacokinetics; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000187:drug effects; D008297:Male; D009928:Organ Specificity; D051381:Rats; D017208:Rats, Wistar; D013696:Temperature; D014700:Verapamil / Q000494:pharmacology
D018435:ATP Binding Cassette Transporter, Subfamily B; D004655:Emulsions; D014700:Verapamil; D019833:Genistein