The use of hot‐stage microscopy and thermal micro‐Raman spectroscopy in the study of phase transformation of metoclopramide HCl monohydrate

The aim of this work was to investigate the transformation behavior of metoclopramide HCl with monohydrate (MCP HCl H₂O) using differential scanning calorimetry (DSC), thermogravimetric analysis, hot‐stage microscopy (HSM), and thermal micro‐Raman spectroscopy. The results of the present study indicate that the three‐step phase transformation of MCP HCl H₂O was clearly determined via the thermal‐dependant Raman spectral changes. These three steps of phase transformation were dehydration, recrystallization, and new crystal formation, which were markedly correlated with the endothermic and exothermic results of DSC study and the observations of HSM. The results generally evidence that MCP HCl H₂O crystals were first dehydrated to form an anhydrous sample, then recrystallized and transformed to a new crystal form of MCP HCl. Copyright © 2011 John Wiley & Sons, Ltd.