Liquid crystals and colloids in water-amiodarone systems

Amiodarone, a molecule used in treatment of heart arrhythmias, presents several metastable states. Transparent sols (50 mg/mL) and gels (100 mg/mL) are obtained by heating amiodarone crystals in water to 70 degrees C and cooling to 20 degrees C. These preparations diluted in water remained transparent above 1.5 mg/mL, but further dilutions resulted in a milky cloud, which was studied by light scattering and photon correlation spectroscopy. A swollen smectic phase appeared at 200 mg/mL and another isotropic gel at 500 mg/mL. This behavior is similar to that of some classical lyotropic liquid crystals.