ABSORPTION-PARTITION RELATIONSHIPS FOR TRUE HOMOLOGOUS SERIES OF XENOBIOTICS AS A POSSIBLE APPROACH TO STUDY MECHANISMS OF SURFACTANTS IN ABSORPTION .4. PHENYLACETIC ACID-DERIVATIVES AND ANIONIC SURFACTANTS

This paper - the latest in this series of reports - deals with the effects of the anionic surfactant sodium lauryl sulfate on the colonic absorption of acidic xenobiotics (phenylalkylcarboxylic acids), as compared with those exerted by the nonionic polysorbate 80. The effects of these surfactants are qualitatively identical but quantitatively different. Thus, the increase in polarity of the colonic absorbant membrane is greater with lauryl sulfate, whereas micellar solubilization is much higher with polysorbate. As for the rest (i.e. the elimination of the stagnant aqueous diffusion layer as a limiting step for absorption), the two surfactants behave in a similar way. The biopharmaceutical implications of this comparative behaviour are briefly discussed.