Differential scanning calorimetry and scanning thermal microscopy analysis of pharmaceutical materials

Micro-thermal analysis (muTA) by scanning thermal microscopy is being used increasingly for the analysis of pharmaceutical dosage forms. However, there is currently little evidence to show that muTA data can compare directly with that from the established approach of differential scanning calorimetry (DSC). This work compares DSC and muTA data from an active vitamin 136 analogue, pyridoxal hydrochloride, and two commonly used pharmaceutical excipients, Mannitol and Avicel(TM) which are used in its formulation. It is found that muTA 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 muTA offers the opportunity to study single particles and the interfacial region between particles, data which is currently inaccessible through the DSC technique. (C) 2002 Elsevier Science B.V. All rights reserved.