The epithelium of the small intestine provides a physical and biochemical banner that restricts the transcellular absorption of orally dosed drugs into the bloodstream through mechanisms including P-glycoprotein (Pgp) and Cytochrome P450 3A4 (CYP3A4). P-glycoprotein is constitutively expressed on the apical membrane of the intestinal lumen where it can act to limit xenobiotic absorption by excreting drugs that have reached the cell interior back into the intestinal lumen. CYP3A4, the most abundant phase one drug metabolising enzyme in humans, can metabolise over fifty percent of commercially available drugs and is located apically within the enterocytes where it can restrict bioavailability by metabolising xenobiotics.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:493464 |
| Date | January 2007 |
| Creators | Eastwood, Martin |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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