Differential scanning calorimetry and scanning thermal microscopy analysis of pharmaceutical materials.

Micro-thermal analysis (microTA) by scanning thermal microscopy is being used increasingly for the analysis of pharmaceutical dosage forms. However, there is currently little evidence to show that microTA data can compare directly with that from the established approach of differential scanning calorimetry (DSC). This work compares DSC and microTA data from an active vitamin B6 analogue, pyridoxal hydrochloride, and two commonly used pharmaceutical excipients, Mannitol and Avicel which are used in its formulation. It is found that microTA provides precise and accurate micro-thermal analytical data with 0.1 K thermal sensitivity, which is comparable to that obtained by DSC measurements of bulk samples. It is also shown that microTA offers the opportunity to study single particles and the interfacial region between particles, data which is currently inaccessible through the DSC technique.