During the process of investigating a stable dosage form, it is important to find out if there is any interaction between the active pharmaceutical ingredient and the particular excipient, as this can influence the stability or bioavailability of the drug.
No interaction means that the cumulative curve contains all effects which are already present in the DSC curves of the single components ‒ but nothing more and nothing less. To get an idea how fully compatible curves which are composed of several components might appear, SuperPosition software functionality can be used.
The graphic, showing the DSC signals of pure ibuprofen (black), pure magnesium stearate (red) and a 90:10 mixture of ibuprofen and magnesium stearate (blue), reveals interactions.
Depending on the material properties, information about interactions can also be obtained by TGA.