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Analysis of Algorithms Predicting Blood: Air and Tissue: Blood Partition Coefficient from Solvent Partition Coefficients for Use in Complex Mixture Physiological Based Pharmacokinetic/Pharmacodynamic Modeling

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Final rept. Jan-Nov 2003

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Algorithms predicting tissue and blood partition coefficients PCs from solvent properties octanolwater, saline or waterair, oilair coefficients were compared to assess their usefulness for a petroleum mixtures physiologically based pharmacokineticpharmacodynamic model. Measured bloodair and tissueblood PCs were sought from literature resources for 14 JP-8 components. PCs, mainly from vial equilibration experiments, were separated by species rat and human and averaged by tissue and chemical. Average experimental PCs were then compared with predicted PCs calculated using algorithms from nine published sources. The algorithms chosen use solvent PCs due to the relative accessibility of these parameters. Tissueblood PCs were calculated from ratios of predicted tissueair and experimental bloodair values PCEB. Calculated PCs were evaluated using percent error compared to the experimental value. Of the 231 calculated values, 29 performed within - 20 of the experimental PC values. Algorithms were divided into three main types. Empirical equations derived from linear regression of experimental PC data, physiologically based equations based on water and lipid components of a tissue type, and hybrid equations physiological parameters and empirical factors combined each performed equally well. PCEs values were compared with tissueblood PCs calculated from ratios of predicted tissueair and predicted bloodair values PCsub pb. Overall, 68 of PCER values had smaller absolute percent errors than PCsub pb values. Physiological equations should not be used to calculate PCsub pb values as 100 of these PCps values had higher absolute percent errors than corresponding PCsub eb values. If calculated PC values must be used in models, a comparison of experimental and predicted PCs for chemically similar compounds is advisable, so one understands the expected error level in calculated values.

Subject Categories:

  • Toxicology
  • Pharmacology
  • Organic Chemistry

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