Studies on the reliability of a bihyperbolic functional absorption model. I. Ring-substituted anilines

Abstract

The present study reviews and checks the rearranged master lines of the functional bihyperbolic absorption model proposed by Plá-Delfina and Moreno, by examining the correlations between absorption rate constants experimentally found in the small intestine and in the colon of the rat, and two types of partition constants for a series of ring-substituted anilines, of low to medium molecular weight. Evidence is given which demonstrates the reliability of the bihyperbolic equation for the small intestine data, showing the importance of the type of substitution in the absorption rate of compounds; for the colonic data, the collapsed, monohyperbolic form of this equation (i.e., the Wagner-Sedman equilibrium model) applies, independent of the nature and position of the group substituents in the aniline molecule. This means that, as the bihyperbolic model equation predicts, aqueous pore diffusion is a crucial factor, as important as membrane permeation, in absorption in the small intestine, whereas in the colon only this latter route is operative. The perspectives opened by the application of the model to gastrointestinal absorption studies are also discussed.

Partition Behavior of Anilines in Bulk‐Phase and High‐Performance Liquid Chromatographic Systems: Influence on Correlation with Biological Constants

“…e Colonic absorption rate constant; data from ref. 10 The vvalues for each mobile phase were calculated with eq 1, with the figures shown in the last two lines of Tables I1 and I11 as reference. Figure 2 is a representative plot of such values versus mobile phase composition.…”

Evidence of a specialized transport mechanism for the intestinal absorption of baclofen

“…In the opinion of the authors, however, the V m and K , values obtained with the aid of the integral method (equation (7)) are better for describing baclofen absorption kinetics since, for several reasons, the fitting to differential expressions (equations (3), (5), and (6)) implies modifying the true experimental data (i.e. A and t).…”

Influence of leucine on intestinal baclofen absorption as a model compound of neutral α‐aminoacids

“…Thus we fitted the equations (8) and (9) acts as an inhibitor should approach its K , value in free solution.23 Whenever the inhibitor is transported by a second carrier unable to transport the drug, however, K, becomes a pseudoconstant, since it depends on two carrier systems simultaneously, and it cannot be equal to Ki. The same reasoning can be applied when the drug is transported by two carrier systems and the inhibitor is transported by only one of them.…”