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Application Notes
Tracking pseudo polymorph transition
with Lasentec® FBRM® and PVM®
as presented by Olivier Monnier
Sanofi Synthelabo
at Lasentec® Users’ Forum 2001 - Barcelona
The purpose of this study was to increase the final purity of a drug
substance. Crystal shape was tracked using Lasentec® FBRM® and PVM®
to ensure selection of parameters that would improve final product
properties.
The first step towards defining any crystallization process is choosing the
solvent. If a solvent that might give a pseudo polymorph is selected, the
non-solvated form might be less stable than the solvent, and problems
might be encountered getting this form out during the process. Knowledge
of pseudo polymorphs is also helpful in avoiding certain solvents in the
formulation step and knowing the relative thermodynamic stability of the
solvate. This gives a better understanding of crystal/solvent interactions
and better ability to control the crystallization and quality of the final
product.
®
Measurements with PVM showed very large, needle-shaped crystals of
the non-solvate form. The transformation was quite fast, occurring in
only 24 hours. FBRM® statistics related to the crystal form of interest were
applied to track the transformation. When the transformation occurred,
the number of FBRM® chord length counts increased. This was true for all
particle size classes, making it very easy to see both the change in fine
particles and the transformation.
It was determined that both FBRM® and PVM® were useful in better
understanding the behavior of this drug substance in solvent.
Application Notes
Mettler-Toledo
Mettler-Toledo Xxxxx
AutoChem, Inc.
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Email: [email protected]
M-2-126 Rev E (05/2006) Printed in USA
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