Calculation of MTDSC Signals, Factors Effecting the Signals and Applications in Drug Development: A Recent Study

The author focuses on the basic principle of Modulated Temperature Differential Scanning Calorimetry (MTDSC), the advantages of MTDSC over conventional DSC, the calculation of heat flow and heat capacity components, factors affecting MTDSC signals, and MTDSC application in drug development in this paper. In MTDSC, a sinusoidal modulation is layered on top of a traditional linear heating ramp, in which the sample temperature rises steadily over time.

The linear heating rate provides the same information as a regular DSC, however the sinusoidal heating rate determines the fraction of total heat flow that corresponds to the changing heat rate. The overall heat flow rate is determined by heat capacity and heat capacity change. Reversing heat flow, also known as the heat capacity component of total heat flow, is a portion of heat flow.The kinetic component is time dependent and is also known as non-reversing heat flow since it does not adapt to changes in the heating rate. Optimized experimental settings must be chosen for accurate measurements of heat flow and heat capacity components. MTDSC is used in preformulation studies to identify Tg, polymorphic forms, and polymorphic transitions, as well as to ensure stability through drug excipient compatibility tests and to calculate the enthalpy of polymorphic transitions.