New polymorphs of well-known drugs: the cases of bisacodyl and theophyline

Title

New polymorphs of well-known drugs: the cases of bisacodyl and theophyline
Poster

Description

Ventsislav Dyulgerov1, Boris Shivachev2
1Faculty of chemistry and pharmacy, University of Sofia “St. Kliment Ohridski”, Bulgaria
2Institute of mineralogy and crystallography “Acad. Ivan Kostov”, Bulgarian Academy of Sciences, Sofia, Bulgaria.

Subject

The crystal structures of the new polymorphs of bisacodyl ([([4-[(4-acetyloxyphenyl)-pyridin-2-ylmethyl] phenyl] acetate)) and theophyline (1,3-dimethylxanthine) were solved by single X-ray diffraction analysis. Starting bisacodyl was extracted from suppositories with petroleum ether and the precipitate was recrystallized from acetone. The crystallization and subsequent structure solution based on X-ray single crystal diffraction resulted in the elucidation of a new noncentrosymmetric structure of bisacodyl (Space group №19, a = 8.06862(18) Å, b = 8.27567(18) Å, c = 28.3631(7) Å.). A commercial grade theophylline was also recrystallized and a the powder diffraction data showed the presence of an “unknow” crystal phase. Subsequent single crystal diffraction analysis showed that theophyline crystallized in monoclinic space group Pn, with unit cell parameters a = 3.8744(4) Å , b = 12.8 898(9) Å, c = 8.1167(6) Å and β = 98.965(8)°. The novel polymorphic form of theophylline is build up based on N-H…N hydrogen bonding interaction.
Key words: Polymorph, polymorphism, single crystal, powder diffraction