OBJECTIVETo study the absorption and transportation characteristic of 1-ephedrine (LEP), d-pseudoephedrine (DPEP), d-norpseudoephedrine (DNPE) isolated from Herba Ephedrae, which were classified the alkaloids, in human intestinal epithelium.

METHODCaco-2 (the human colon adeno carcinoma cell lines) cells monolayer was used as an intestinal epithelial cell model. The permeability of the three alkaloids from apical side (AP side) to basolateral side (BL side) or from BL side to AP side was evaluated. The concentration of the three alkaloids was measured by HPLC coupled with UV detector. Transportation parameters and apparent permeability coefficients (P(app)) were then calculated, and P(app) values were compared with the reported values for model compounds, propranolol and atenolol.

RESULTThe P(app) values of the three alkaloids in the bi-directional transportation were quantitative degree of 1.0 x 10(-5) cm x s(-1), which was comparable with the P(app), value of propranolol, which is a transcellular transportation marker and a well-transported compound with a P(app) > or = 1.0 x 10(-5) cm x s(-1). The absorption and transportation of the three alkaloids were positive correlation to the concentration of 10-200 mol x L(-1).

CONCLUSIONLEP, DPEP and DNPE can be absorbed across intestinal epithelial cells by passive diffusion mechanism, and are well absorbed compounds.