Comparison of mass transfer models for determination of the intestinal permeability

Background and the purpose of the study: In determination of the permeability of theintestinal wall by external perfusion techniques, several models have been proposed. In thepresent study three models were used for experimental results that differ in theirconvection and diffusion assumptions.Material and Methods: Permeability coefficients for 13 compounds (metoprolol,propranolol, naproxen, ketoprofen, furosemide, hydrochlorothiazide, cimetidine, ranitidine,atenolol, piroxicam, antipyrine, ibuprofen and carbamazepine) with known humanintestinal permeability values were determined in anaesthetized rats by different masstransfer models and plotted versus the observed human intestinal permeabilities.Results: The calculated dimensionless wall permeability values were in the range of 0.37 –4.85, 0.38-6.54 and 0.41-16.59 for complete radial mixing, mixing tank and laminar flowmodels respectively. The results indicated that all of the models work relatively well forour data despite fundamentally different assumptions. The wall permeabilities were in theorder laminar flow mixing tank complete radial mixing.Conclusion: Although laminar flow model provides the most direct measure of theintrinsic wall permeability, it has limitations for highly permeable drugs such as ibuprofen.The normal physiological hydrodynamics is more complex and more investigation isrequired to find out the real hydrodynamics.