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Journal of Thermal Analysis and Calorimetry
Authors: G. Bruni, V. Berbenni, C. Milanese, A. Girella, P. Cofrancesco, G. Bellazzi, and A. Marini

Abstract  

In this work the solid-state characterization of anhydrous D-mannitol has been performed: α and β modifications can be distinguished only by XRPD and FTIR as they show melting temperature and enthalpy that are the same within the standard deviation. The understanding of the thermal behaviour of the δ form (obtained by re-crystallization in acetone) has required XRPD experiments performed at variable temperature. This form during heating undergoes a solid phase transition to α modification. By cooling a melted sample, under a wide range of experimental conditions, a very fast crystallization occurs. Independently of the starting crystal form (β or δ form), the re-crystallization of D-mannitol from melt always leads to α form.

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Journal of Thermal Analysis and Calorimetry
Authors: Giovanna Bruni, C. Milanese, G. Bellazzi, V. Berbenni, P. Cofrancesco, A. Marini, and M. Villa

Abstract  

The processes of production of drugs and dosage forms in the solid state often cause unwanted transformation of portions of the substances into amorphous state, with significant changes of properties such as stability and bio-availability. When this amorphous fraction is of the order of a few percent, it usually goes unnoticed, but it should be accurately determined within a quality control system. In this work, we consider a model drug, perphenazine, where partial amorphisation may be induced by standard mechanical treatments. We show that Differential Scanning Calorimetry (DSC) leads to consistent estimations of the amorphous fractions induced by the treatment. Furthermore, DSC also yields the expected amounts of amorphous perphenazine when analysing known mixtures of perfectly crystalline samples (untreated) and partially amorphous samples (treated). We show that even amorphous fractions of the order of 1% are accurately estimated by our method.

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