No abstract

Compressibility properties of pharmaceutical materials are widely characterized by measuring the volume reduction of a powder column under pressure. Experimental data are commonly analyzed using the Heckel model from which powder deformation mechanisms are determined using mean yield pressure (Py). Several studies from the literature have shown the effects of operating conditions on the determination of Py and have pointed out the limitations of this model. The Heckel model requires true density and compacted mass values to determine Py from force-displacement data. It is likely that experimental errors will be introduced when measuring the true density and compacted mass. This study investigates the effects of true density and compacted mass on Py. Materials having different particle deformation mechanisms are studied. Punch displacement and applied pressure are measured for each material at two compression speeds. For each material, three different true density and compacted mass values are utilized to evaluate their effect on Py. The calculated variation of Py reaches 20%. This study demonstrates that the errors in measuring true density and compacted mass have a greater effect on Py than the errors incurred from not correcting the displacement measurements due to punch elasticity.

No abstract

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 °C and cooling to 20 °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.