Press Release No. 1/2012 of 17 January 2012
BAM’s analytical chemists have observed an unusually fast crystallisation of the antihypertensive drug nifedipine [1]. They can measure crystallisation processes that occur 10,000 times faster than previously known. Knowledge of the different crystallisation pathways is important in order to characterise the specific impact of this crystallisation on the development of pharmaceuticals.
The drug nifedipine is available in various chemical modifications, which are constructed of the same atoms, but differ in their spatial arrangement and hence in their properties. Therefore, knowledge of all modifications and their conversion (crystallisation) pathways is important. Thus one can selectively stabilise a modification of the active ingredient in the production.
Nifedipine is available in an amorphous (glassy) and two crystalline modifications (α, β). The amorphous form of a compound is generally more soluble, but less stable than its crystalline counterpart. The modifications can, under certain conditions, be converted into each other. The researchers have now observed the extraordinarily rapid transition from the amorphous state to the metastable β-modification using in situ Raman spectroscopy.
The β-modification is then stable at 25 degrees Celsius for less than 10 minutes before it is converted in turn into the stable α-modification. The speed of the transformation implies that conventional diffusion is not the driving force for the formation of different modifications. Instead, the researchers explained, the molecules pre-orient themselves in space and thus the rapid crystallisation becomes possible.
BAM’s current work in this area is being funded by DFG within the "Non-equilibrium crystalline phases" key research programme (1415 SPP).
[1] Chem. Commun., 2012, DOI: 10.1039/C1CC16301A
Contact:
Dr. rer. nat. Franziska Emmerling
Department 1 Analytical Chemisty; Reference Materials
E-Mail: franziska.emmerling@bam.de
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