Dissociation Constants and Partition Coefficients of Sympathomimetic Amines, their Precursors and Metabolites

Abstract

The dissociation constants (pKa values) and the apparent partition coefficients (log D values) of naturally occurring sympathomimetic amines, their precursors, and their O-methylated and deaminated metabolites were determined. These values were also estimated for a series of synthetic sympathomimetic amines. The dissociation constants were determined by potentiometric titration; the apparent partition coefficients were obtained from the ratio of the concentration of the compound in the lipid phase (n-octanol) to the concentration of the unionized plus ionized species of the compound in the aqueous phase (phosphate buffer pH 7.4).