Polymorphism by an Alternative to XRD Analyses
An Alternative to XRD (X-Ray Diffraction) – Polymorphism in APIs can also be characterized by DSC (Differential Scanning Calorimetry)
The influence of polymorphism in various scientific fields is well known. Polymorphism is also common in pharmaceutical drug development and the preparation and characterization of polymorphs of drugs are of paramount importance. In fact, the structure of these compounds has implications on medicinal and pharmaceutical properties such as bioavailability, suitability for required formulations, structural stability and shelf life.
Active ingredients in drugs are molecules that can adopt a variety of conformations. The specific interactions between polar groups present in these molecules result in crystalline structures that differ from each other in their space lattice type, molecular conformation, or both characteristics simultaneously.
X-ray diffraction (XRD) is used to study polycrystalline and amorphous materials non-destructively. The method is based on the diffraction of X-rays resulting from the interaction between the X-rays and the electrons of the atoms.
An alternative method for characterizing polymorphism in API’s is Differential Scanning Calorimetry (DSC). Suisse TP offers this effective technique to investigate polymorphism of pharmaceutical ingredients. Based on different crystal shapes, DSC can detect the different melting points and heat of fusions of the different polymorphs. A big advantage of DSC is that this method requires no sample pretreatment and performs measurements quickly.
As an example, Figure 1 shows a DSC thermogram and the different melting temperatures of two crystalline forms of d9-THC Naphthoyl ester.
DSC-Thermogram of two crystalline forms of d9-THC-Naphthoylester.