Enhanced intestinal absorption of amino acids and amino acid-like drug by possible formation of enamine in administered solution by the presence of ethylacetoacetate.

Ethylacetoacetate promoted the colonic and the jejunal absorption of amino acids such as L-phenylalanine and D-phenylalanine when administered in aqueous solution. Enhanced absorption of these isomers of amino acid might occur via a formation of enamine, which was observed in aqueous solution by monitoring ultraviolet absorbance at 288 nm. Since mixture of L- or D-phenylalanine and ethylacetoacetate in aqueous solution enhanced colonic absorption of cefmetazole while the solution did not affect so much on the jejunal absorption of cefmetazole compared to the colonic absorption of it, enhancing action of enamine probably produced in aqueous solution may be more effective at the colonic compartment.