Structural Elucidation of the Neuraminidase Inhibitor Zanamivir (Relenza): Creeping and Diffusion for Polymorph Separation

Zanamivir, the active ingredient of the antiviral drug Relenza, is the most potent of the four currently approved neuraminidase inhibitors
for treatment of pandemic strains of influenza. A combination of solution
creeping and vapor diffusion of antisolvent was successfully applied
to obtain two crystalline polymorphic dihydrates and to accomplish
the first structure determination of zanamivir with X-ray diffraction.