Model prodrugs for the intestinal oligopeptide transporter: model drug release in aqueous solution and in various biological media

TY - JOUR

T1 - Model prodrugs for the intestinal oligopeptide transporter

T2 - model drug release in aqueous solution and in various biological media

AU - Nielsen, C U

AU - Andersen, R

AU - Brodin, Birger

AU - Frokjaer, S

AU - Steffansen, B

PY - 2001

Y1 - 2001

N2 - The human intestinal di/tri-peptide carrier, hPepT1, has been suggested as a target for increasing intestinal transport of low permeability compounds by creating prodrugs designed for the transporter. Model ester prodrugs using the stabilized dipeptides D-Glu-Ala and D-Asp-Ala as pro-moieties for benzyl alcohol have been shown to have affinity for hPepT1. Furthermore, in aqueous solution at pH 5.5 to 10, the release of the model drug seems to be controlled by a specific base-catalyzed hydrolysis, indicating that the compounds may remain relatively stable in the upper small intestinal lumen with a pH of approximately 6.0, but still release the model drug at the intercellular and blood pH of approximately 7.4. Even though benzyl alcohol is not a low molecular weight drug molecule, these results indicate that the dipeptide prodrug principle is a promising drug delivery concept. However, the physico-chemical properties such as electronegativity, solubility, and log P of the drug molecule may also have an influence on the potential of these kinds of prodrugs. The purpose of the present study is to investigate whether the model drug electronegativity, estimated as Taft substitution parameter (sigma*) may influence the acid, water or base catalyzed model drug release rates, when released from series of D-Glu-Ala and D-Asp-Ala pro-moieties. Release rates were investigated in both aqueous solutions with varying pH, ionic strength, and buffer concentrations as well as in in vitro biological media. The release rates of all the investigated model drug molecules followed first-order kinetics and were dependent on buffer concentration, pH, ionic strength, and model drug electronegativity. The electronegativity of the model drug influenced acid, water and base catalyzed release from D-Asp-Ala and D-Glu-Ala pro-moieties. The model drug was generally released faster from D-Asp-Ala- than from the D-Glu-Ala pro-moieties. In biological media the release rate was also dependent on the electronegativity of the model drug. These results demonstrate that the model drug electronegativity, estimated as Taft (sigma*) values, has a significant influence on the release rate of the model drug.

AB - The human intestinal di/tri-peptide carrier, hPepT1, has been suggested as a target for increasing intestinal transport of low permeability compounds by creating prodrugs designed for the transporter. Model ester prodrugs using the stabilized dipeptides D-Glu-Ala and D-Asp-Ala as pro-moieties for benzyl alcohol have been shown to have affinity for hPepT1. Furthermore, in aqueous solution at pH 5.5 to 10, the release of the model drug seems to be controlled by a specific base-catalyzed hydrolysis, indicating that the compounds may remain relatively stable in the upper small intestinal lumen with a pH of approximately 6.0, but still release the model drug at the intercellular and blood pH of approximately 7.4. Even though benzyl alcohol is not a low molecular weight drug molecule, these results indicate that the dipeptide prodrug principle is a promising drug delivery concept. However, the physico-chemical properties such as electronegativity, solubility, and log P of the drug molecule may also have an influence on the potential of these kinds of prodrugs. The purpose of the present study is to investigate whether the model drug electronegativity, estimated as Taft substitution parameter (sigma*) may influence the acid, water or base catalyzed model drug release rates, when released from series of D-Glu-Ala and D-Asp-Ala pro-moieties. Release rates were investigated in both aqueous solutions with varying pH, ionic strength, and buffer concentrations as well as in in vitro biological media. The release rates of all the investigated model drug molecules followed first-order kinetics and were dependent on buffer concentration, pH, ionic strength, and model drug electronegativity. The electronegativity of the model drug influenced acid, water and base catalyzed release from D-Asp-Ala and D-Glu-Ala pro-moieties. The model drug was generally released faster from D-Asp-Ala- than from the D-Glu-Ala pro-moieties. In biological media the release rate was also dependent on the electronegativity of the model drug. These results demonstrate that the model drug electronegativity, estimated as Taft (sigma*) values, has a significant influence on the release rate of the model drug.

KW - Algorithms

KW - Animals

KW - Buffers

KW - Carrier Proteins

KW - Chromatography, High Pressure Liquid

KW - Drug Carriers

KW - Humans

KW - Hydrogen-Ion Concentration

KW - Intestines

KW - Kinetics

KW - Plasma

KW - Prodrugs

KW - Solubility

KW - Solutions

KW - Swine

KW - Symporters

M3 - Journal article

C2 - 11337056

SN - 0168-3659

VL - 73

SP - 21

EP - 30

JO - Journal of Controlled Release

JF - Journal of Controlled Release

IS - 1

ER -