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Reliable Mechanochemistry: Protocols for Reproducible Outcomes of Neat and Liquid Assisted Ball-mill Grinding Experiments
Published on: January 23, 2018
Transformation of an active pharmaceutical ingredient upon high-energy milling: A process-induced disorder in
Benjamin Schammé1, Nicolas Couvrat2, Pascal Malpeli3
1Normandie Univ, Laboratoire SMS-EA3233, Univ Rouen, F-76821 Mont Saint Aignan, France; Normandie Univ, AMME-LECAP EA 4528 International Lab, Univ Rouen, Avenue de l'Université, BP12, F-76801 Saint Etienne du Rouvray, France.
Abstract:
This study investigates for the first time the thermodynamic changes of Biclotymol upon high-energy milling at various levels of temperature above and below its glass transition temperature (Tg). Investigations have been carried out by temperature modulated differential scanning calorimetry (TM-DSC) and X-ray powder diffraction (XRPD). Results indicate that Biclotymol undergoes a solid-state amorphization upon milling at Tg-45 °C. It is shown that recrystallization of amorphous milled Biclotymol occurs below the glass transition temperature of Biclotymol (Tg=20 °C). This displays molecular mobility differences between milled Biclotymol and quenched liquid. A systematic study at several milling temperatures is performed and the implication of Tg in the solid-state transformations generally observed upon milling is discussed. Influence of analysis temperature with respect to interpretation of results was investigated. Finally, it is shown that co-milling Biclotymol with only 20 wt% of amorphous PVP allows a stable amorphous dispersion during at least 5 months of storage.
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