Binding of (+)- and (-)-isomers and the racemate of sodium 2[6-(4-chlorophenoxy)-hexyl]-oxiran-2-carboxylate dihydrat (etomoxir) to the human serum albumin (HSA) was studied by the gel filtration method. The experimental results are presented graphically using the method of Scatchard. Measurements revealed the following data on the binding: (a) for either of the isomers there are two independent and nonequivalent classes of binding sites on the HSA molecule; (b) the binding constants calculated for both isomers were of the same order of magnitude (K1/n approximately 20 x 10(5) L.mol-1 for the concentration range 3.48-4.0 x 10(-5) mol.L-1, and K2/n approximately 2 x 10(5) L.mol-1 for the concentration range 4.28-10 x 10(-5) mol.L-1, for the high and low affinity binding sites, respectively); (c) statistically significant difference (p < or = 0.05) between the low affinity binding constant estimated for the (+)-isomer K2 = 1.9 +/- 0.1 x 10(5) L.mol-1) compared with the constants evaluated for the (-)-isomer and racemic etomoxir (2.6 +/- 0.1 and 2.9 +/- 0.2 x 10(5) L.mol-1, respectively); and (d) both isomers are bound into a high extent to the HSA molecule (i.e., at a ligand concentration of 3.48 x 10(-5) mol.L-1, the percent of binding was approximately 95% for the compound tested. When plotting the percent binding (% Cb) against the total concentration (Ctot), a statistically significant difference (p < or = 0.05) was obtained between the slope of the straight line for the (+)-isomer and those for other two compounds.(ABSTRACT TRUNCATED AT 250 WORDS)