Interaction of Amphotericin B with cholesteryl palmityl carbonate ester.

A cholesteryl carbonate ester was prepared and evaluated as a possible thermotropic liquid crystal excipient for dry powder inhalers. Cholesteryl palmityl carbonate (CPC) was synthesized, and the phase behavior was characterized by differential scanning calorimetry, transmission electron microscopy, polarized light microscope, small angle X-ray diffraction, and solid-state nuclear magnetic resonance spectroscopy. Amphotericin B (AmB) was incorporated into CPC at various mole% (7.7, 14.3, 25, 33.3, and 50) using a solvent evaporation method. The amount of AmB loaded into liquid crystal was limited. The mixture of AmB in liquid crystal did not produce a new complex; rather, the addition of AmB affected the orientational order and the motional aspects of liquid crystal molecules.