Excipient compatibility screening using DSC

Use of DSC has been proposed as a rapid method for evaluating the physicochemical interaction between two components and can provide fast and reliable information about potential physical or chemical incompatibihties between the formulation components through the appearance, shift or disappearance of endotherms or exotherms and/or variations in the relevant enthalpy values [44,45]. However, interpretation of DSC results is not always easy, and thoughtful evaluation is necessary to avoid misinterpretation and erratic conclusion [46]. 

The basic approach is that of mixing two components (drug and excipient) typically in a 50/50 mix and then performing a DSC scan. The melting profile of the two individual components is then compared with the scan of the mixture. Ideally, if no interaction occurs then the mixture should show equivalent transitions to that of the individual components. If it does not, some interaction is indicated. 

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