The effects of mucus glycoproteins on the bioavailability of tetracycline. III. Everted gut studies

Abstract

Everted rat intestinal sacs were used to measure the transport rate of tetracycline across gut tissue. The endogenous mucus secreted by the tissue, in vitro, was shown to have a significant effect on the rate of drug transfer with removal of this layer resulting in rate increases of between 60 and 90% depending on whether the segment was derived from the distal or proximal portion of the small intestine, respectively. A purified exogenous mucus dispersed in the sac reduced the transport rate only slightly. The bile salts taurodeoxycholate and deoxycholate increased drug transport in denuded gut sections but this was considerably reduced in the presence of the native mucus layer. Cetyltrimethylammonium bromide and sodium dodecylsulphate both reduced transport rates but to a lesser extent when the mucus layer was intact.