Jan 17, 2007
Ambiguous aspirin
Two back-to-back papers in the well-known chemistry journal Angewandte Chemie recently could have potentially serious consequences for the pharmaceutical industry, because they reveal what the authors claim are inherent ambiguities in the crystalline forms of aspirin.
A team of scientists from Denmark, Germany, and India suggest that the recently reported form II of the ubiquitous pharmaceutical may indeed exist but the crystallographic evidence could just as readily be interpreted as being from a single crystal of form I. The findings could have implications for patent arguments over novel forms of the purportedly generic drug.
Even from the early days of crystal studies into aspirin, there were serious issues surrounding its structure. PJ Wheatley obtained the first crystal structure in 1964, but certainly not without a degree of ambiguity. “After Wheatley, Chick Wilson got very high R-factors in his neutron study of 2000,” Desiraju told SpectroscopyNOW.com, “this is what was nagging me throughout, why were these R-factors so high?” Desiraju and his colleagues suggest that the Zaworotko study does not represent much of an improvement on the precision of these earlier studies and moreover confounds attempts to define a new polymorphic form of aspirin.
Read the full story on SpectroscopyNOW.com
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Steve M said,
January 17, 2007 at 1:55 pm
C&EN also reported on this issue, and said that Zaworotko and Peterson were rather taken aback by the stance of Desiraju and his colleagues.
The journal quotes Peterson as saying: “”It was such an attacking sort of paper.”
But isn’t this sort of paper exactly what is needed in science to shake things up and make sure the original results being reported in peer-reviewed journals are robust and can stand up to detailed scrutiny?
bt said,
January 17, 2007 at 2:03 pm
ref
Janua 1, 2007, iss 1 pages 27-28
Srinivasan said,
February 26, 2007 at 12:16 pm
The level of error is very much elementary for the experience of Zaworotko! Having just 13 non-hydrogen atom in the aspirin molecule and without any disorder – the reported R-factor is too high! The DSC thermal analysis of the Zaworotko’s form II doesn’t show sharp melting point.
Hence this sort of paper got exactly what is needed.