High-pressure infrared and Raman studies of polymorphism in pharmaceutical compounds: Spironolactone, Forms I and II

[Display omitted] •Pressure-tuning IR and Raman spectra of the two polymorphic forms of spironolactone have been examined for the first time.•Both forms undergo structural transformations under pressure but over different pressure ranges.•No interconversion of the two forms under high pressures. The infrared and Raman spectra of the two polymorphic forms, I and II, of the synthetic steroid spironolactone (C24H32O4S) have been examined under high pressures up to about 50kbar with the aid of a diamond-anvil cell. While the differences in peak wavenumbers between the two polymorphs are small, the difference in the pressure dependence is dramatic. Both forms undergo structural transformations under pressure, but over different pressure ranges.