Ultracentrifugal study of effect of sodium chloride on micelle size of fusidate sodium

Apparent micellar molecular weights were determined with the antibiotic fusidate sodium by ultracentrifugation in varying counterion concentrations (Na+). The effects of buffer salts, pH, sodium chloride concentration, and drug concentration were studied. The results strongly support the concept of the formation of primary micelles composed of five monomer units, followed by aggregation of the pentomers into larger micelles as salt concentration increases.