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We currently have a paper in press in the European J Pharm which is
entitled: Localisation of drug permeability along the rat small
intestine, using markers of the paracellular, transcellular and some
transporter routes. Olivier Lacombe et al.
Using rat intestinal gut sacs, in this study we showed that the drug
permeability is relatively constant along the length of the jejuneum,
but is lower in the duodenum and the ileum.
Digoxin shows a decrease in permeability down the intestine, which is
consistent with an increase in P-gp expression down the gut.
More recently, and currently being written up, we have have looked at
the activity of cytochrome P450 enzymes down the rat intestine.
The activity of these enzymes is located maximally in the proximal
It is very low in the duodenum and around 85% of the activity is
located in the first half of the jejunum.
Thus any drugs absorbed in the early part of
the jejunum will be subject to maximal metabolism if they are
substrates of the P450 enzymes present in the gut.
By contrast, if drugs are absorbed in the distal jejunum, which is
still a site of good absorption, they will not be metabolised.
Hope this information useful.
Faculte des Sciences Pharmaceutiques
35 chemin des Maraichers
31062 Toulouse, France
Tel/Fax: + 33 (0)562256885
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Copyright 1995-2010 David W. A. Bourne (firstname.lastname@example.org)