Effect of Complex Formation on the Intestinal Absorption of Tryptophan

概要

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Complexation influence on the rate of absorption of actively transported drug was investigated in the perfused rat small intestine employing L-tryptophan as a model drug and caffeine, 8-chlorotheophylline, 8-methoxycaffeine, 7-hydroxyethyltheophylline, and flavin mononucleotide as complexing agents. Preliminary experiment on the absorption of L-tryptophan by the in situ intestinal perfusion method revealed that the kinetical pattern of the absorption of L-tryptophan approximated to the Michaelis-Menten relationship, D-isomer was also absorbed from the small intestine with apparently minor contribution by a specialized amino acid transport system, and that little absorption occured for both compounds in the rectum. Among the complexing agents studied, 7-hydroxyethyltheophylline and flavin-mononucleotide (FMN) reduced the absorption of L-tryptophan considerably. In the former, mutual effect in the reduction of absorption was observed. For the latter, reduction of the rate of absorption of L-tryptophan was caused neither by direct effect on the absorptive membrane nor by imparing effect on the neutral amino acid transport system but by the decrease of thermodynamic activity of L-tryptophan resulting from molecular complexation with FMN in solution.
公益社団法人日本薬学会の論文
1970-11-25