The use of a perfluorochemical emulsion as a vascular perfusate in drug absorption

In-vitro simultaneous luminal and vascular perfusion using the perfluorochemical emulsion, FC-43 emulsion, as a vascular perfusate, was examined for drug absorption in rat jejunum. The intestinal membrane in this system was found to retain its normal barrier functions for drug transport, as evident from the following: (i) stable absorption clearance of tritiated water and salicylic acid at steady-state, (ii) agreement of this clearance with that by in-situ single-pass luminal perfusion, (iii) active transport of D-glucose and its inhibition by phloridzin and (iv) normal glutamate pyruvate transaminase activity in the intestinal mucosa. FC-43 emulsion gave a more normal absorption site blood flow than the usual vascular perfusate containing erythrocytes and albumin in Krebs-Henseleit bicarbonate buffer solution. Consequently, this emulsion was useful for examining the contribution of blood flow resistance toward drug absorption. The rate-limiting steps of absorption of tritiated water, antipyrine and salicylic acid were examined by perfusion using FC-43 emulsion. The absorption of tritiated water was almost completely blood flow-limited and its absorption clearance may possibly be an approximated absorption site blood flow. The contribution of blood flow resistance to total resistance for antipyrine absorption exceeded that for salicylic acid absorption.