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

Abstract

Differential scanning calorimetry (DSC) was used to investigate the interactions between chlorpromazine HC1 (CPZ) and stearate lubricants. The phase diagram was constructed for each CPZ-stearate system. An unknown endothermic peak at 145~ was found for the CPZstearate 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.It is well known that drug-excipient interactions can exert significant influences on the physico-chemical properties, manufacture and bioavailability of a solid dosage form [1][2][3]. Drug-excipient compatibility testing is a practically reliable preformulation tool to select appropriate excipients for each dosage form design. Thermal methods such as differential thermal analysis (DTA) or differential scanning calorimetry (DSC) are welldeveloped techniques for the detection of incompatibility in drug-excipient mixture [4][5][6]. Since the thermal analysis used is relatively fast, easily interpreted, accurately predictive, and requires only a few test samples, it has been suggested in many studies for the routine screening of potential drugexcipient interactions in preformulation stability testing [7][8][9][10].