Determination of diffusion coefficients of peptides and prediction of permeability through a porous membrane

Abstract

The diffusion coefficient (D) of peptide and protein drugs needs to be determined to examine the permeability through biological barriers and to optimize delivery systems. In this study, the D values of fluorescein isothiocyanate (FITC)-labelled dextrans (FDs) and peptides were determined and the permeability through a porous membrane was discussed. The observed D values of FDs and peptides, except in the case of insulin, were similar to those calculated based on a relationship previously reported between the molecular weight and D of lower-molecular-weight compounds, although the molecular weight range was completely different. The observed D value of insulin was between the calculated values for the insulin monomer and hexamer. The permeability of poly-lysine and insulin through the membrane was determined and the observed values were compared with predicted values by using the relationship between molecular weight and D and an equation based on the Renkin function. The observed permeability of insulin through the membrane was between that of the predicted permeability for the insulin monomer and hexamer. For the permeation of insulin, the determination of D was useful for estimating the permeability because of the irregular relationship between molecular weight and D. The methodology used in this study will be useful for a more quantitative evaluation of the absorption of peptide and protein drugs applied to mucous membranes.

Taylor Dispersion Analysis Compared to Dynamic Light Scattering for the Size Analysis of Therapeutic Peptides and Proteins and Their Aggregates

“… a radius estimated by Stokes-Einstein from diffusion coefficient of D = 4.34*10 −6 cm 2 s −1 as described in (30)…”

Culture of Calu-3 Cells at the Air Interface Provides a Representative Model of the Airway Epithelial Barrier

“…First, diffusion coefficients (D) for each solute were calculated according to the method of Seki and coworkers (25), which has been applied to the diffusion of dextrans (26). log D ¼ À0:434 log MW À 0:4059 ð3Þ…”

Evaluation of the Establishment of a Tight Junction in Caco-2 Cell Monolayers Using a Pore Permeation Model Involving Two Different Sizes

“…15) The D i and the Stokes-Einstein radius (r i ) of four different sized paracellular markers are listed in Table 1. When RD10 is compared with urea, for which there is a 180-fold difference in MW, the value is 0.09 times for D i and 11 times for r i .…”