Compatibility problems of chlorpromazine HCl-stearate lubricants examined by differential scanning calorimetry

Differential scanning calorimetry (DSC) was used to investigate the interactions between chlorpromazine HCl (CPZ) and stearate lubricants. The phase diagram was constructed for each CPZ-stearate system. An unknown endothermic peak at 145°C was found for the CPZ-stearate lubricants; this was affected by the grinding and heating processes. This unknown endothermic peak proved to relate to a polymorphism transition but was not an incompatibility problem. Three polymorphisms of CPZ were also determined by DSC analysis and IR spectrophotometry.