Water as a nonpolar partition medium.

Coacervates have been suggested as models for cytoplasm since cytoplasm is also essentially an aqueous phase of water-protein-colloid complexes. This study on partition coefficient properties made use of coacervate phases as the nonpolar phases in equilibrium with polar water phases. The partition coefficients of four barbiturates were obtained, and their values correlated with those reported in the literature for systems using organic solvents as the nonpolar medium. These values also correlated with reported values for the absorption ranking of the barbiturates in the rat colon. The partition coefficients of theobromine and theophylline in gelatin-benzalkonium chloride coacervate systems were also found to correlate with the partition values reported in the literature for heptane-water and chloroform-water systems. Is is suggested that coacervate systems form a more realistic model for studying and predicting the absorption characteristics of drugs than do conventional organic solvent-water systems.