title: [Effect of Tween-80 on the permeability of rhodamine 123, a P-gp substrate across rat intestinal membranes in vitro].
abstract: OBJECTIVE
  To investigate the effect of Tween-80 in modulating rhodamine123 (R123) permeability across the intestinal membranes.
  
  
  METHODS
  The permeability of R123 or fluorescein sodium (CF) across isolated rat intestinal membranes at the concentration of 5 microg/ml was evaluated using an in vitro diffusion chamber system, in the presence or absence of Tween-80 at different low concentrations. The concentration of R123 or CF in the receptor chamber was determined using fluorospectrophotometry.
  
  
  RESULTS
  The intestinal membrane permeability of R123 gradually decreased from the jejunum to the ileum and then to the colon. The serosal-to-mucosal transport of R123 was much greater than its mucosal-to-serosal transport. In the presence of low concentrations of Tween-80, the absorptive transport of R123 was significantly increased while its secretory transport decreased depending on the concentration of Tween-80. However, Tween-80 at the experimental concentrations was found to obviously affect the CF transport across the intestinal membranes.
  
  
  CONCLUSIONS
  Low concentrations of Tween-80 may promote the absorption of P-gp-mediated drugs and therefore improve the oral bioavailability of these drugs.
authors.affiliation: Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. lgfnf@fimmu.com
authors.forename: Guo-feng
authors.initials: GF
authors.lastname: Li
authors.forename: Ya-fei
authors.initials: YF
authors.lastname: Tan
authors.forename: Dan
authors.initials: D
authors.lastname: Guo
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000818:Animals; D003106:Colon / Q000378:metabolism; D007082:Ileum / Q000378:metabolism; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism; D008297:Male; D010539:Permeability / Q000187:drug effects; D011136:Polysorbates / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D020112:Rhodamine 123 / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D011136:Polysorbates; D020112:Rhodamine 123