Glass-Transition Temperature of the β-Relaxation as the Major Predictive Parameter for Recrystallization of Neat Amorphous Drugs
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Recrystallization of amorphous drugs is currently limiting the simple approach to improve solubility and bioavailability of poorly water-soluble drugs by amorphization of a crystalline form of the drug. In view of this, molecular mobility, α-relaxation and β-relaxation processes with the associated transition temperatures Tgαand Tgβ, was investigated using dynamic mechanical analysis (DMA). The correlation between the transition temperatures and the onset of recrystallization for nine amorphous drugs, stored under dry conditions at a temperature of 296 K, was determined. From the results obtained, Tgαdoes not correlate with the onset of recrystallization under the experimental storage conditions. However, a clear correlation between Tgβand the onset of recrystallization was observed. It is shown that at storage temperature below Tgβ, amorphous nifedipine retains its amorphous form. On the basis of the correlation, an empirical correlation is proposed for predicting the onset of recrystallization for drugs stored at 0% RH and 296 K.
|Journal||Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical|
|Number of pages||6|
|Publication status||Published - 15 Mar 2018|