Authors:Giovanna Bruni, C. Milanese, G. Bellazzi, V. Berbenni, P. Cofrancesco, A. Marini, and M. Villa
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.
Authors:G. Bruni, V. Berbenni, C. Milanese, A. Girella, P. Cofrancesco, G. Bellazzi, and A. Marini
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.