Solubility properties in polymers and biological media: 6. An equation for correlation and prediction of solubilities of liquid organic nonelectrolytes in blood.

Gas/blood partition coefficients, Kgb, and molar solubilities in blood, Sb, of 27 liquid aliphatic nonelectrolyte solutes are described by the equation: log Sb congruent to log (Sg/Kgb) = 1.35-3.05V/100-0.28 pi* + 3.58 beta (at 37 degrees C) r = 0.9870 and SD = 0.144 where Sg is the solute concentration in its saturated vapor at 37 degrees C, given by Sg = Patm/25.4; V is the solute molar volume; and pi* and beta are parameters that are measures of solute dipolarity/polarizability and hydrogen bond acceptor basicity, respectively. The above equation applies to compounds with calculated log solubilities greater than -1.5. A nondipolar solubility reservoir provided by hydrophobic pockets in hemoglobin leads to greater than predicted solubilities for the less soluble alkanes, alkylbenzenes, and chlorobenzenes. It is suggested that equations similar to the one above can be constructed to describe and predict gas-lipid and gas-homogenized tissue, and hence blood-lipid, blood-tissue, tissue-lipid, and tissue-tissue partition coefficients of pharmacologically and toxicologically active solutes.