PLACE OF DSC PURITY ANALYSIS IN PHARMACEUTICAL DEVELOPMENT

DSC purity analysis is based on thermodynamic phase diagrams for substances (purity greater-than-or-equal-to 98%) which undergo a melting point. Impurities which have eutectic behaviour with the analyte are determined together. DSC purity analysis obtained from a single melting event of a 1-2 mg sample is, therefore, extremely attractive for the global assessment of eutectic impurities. The main advantages in early development lie in the very small amount of material necessary and the very fast analysis time. However, the DSC purity analysis cannot replace chromatographic methods which deliver specific individual levels of impurities. Furthermore, a complete validation of a DSC purity method is difficult and time consuming. Despite these limitations, DSC is the best support for the development of chromatographic methods, for purity profile and stability assessment during pharmaceutical development. Parameters of purity determination and validation aspects are discussed. Examples of use in pharmaceutical development are given.