Untersuchung von P Glykoprotein hemmenden Phospholipiden als bioverfügbarkeitssteigernde Hilfsstoffe Zusammenfassung: The efflux transporter P glycoprotein (P gp) is responsible for a diminished intestinal absorption of various drug substances which can impair their oral bioavailability. As a result higher doses are necessary. This in turn raises therapy costs and increases the risk of intestinal side effects due to higher amounts of incompletely absorbed substance. Hence suitable P gp inhibitors as oral bioavailability enhancers are of great interest.Phospholipids exist ubiquitously in nature. They are the most important part of biomembranes play an essential role in lipid metabolism and are involved in many other physiological processes. Moreover due to their amphiphilic properties and the ability to form stable vesicles (liposomes) in an aqueous environment phospholipids are useful pharmaceutical excipients. One application field is the enhancement of solubility and permeability in order to increase the oral bioavailability of drugs. In previous work extraordinary P gp inhibiting properties were found for the medium chain phospholipids 8:0 PC and 10:0 PC as well as for the long chain derivative 22:6 PC