17β-hydroxy-17α-methylandrostano[3,2-c]pyrazole, Stanozolol: The crystal structures of polymorphs 1 and 2 and 10 solvates

17 β -Hydroxy-17α-methylandrostano[3,2-c]pyrazole, also known as stanozolol, is a synthetic steroid derived from testosterone. Crystals grown by sublimation provide the first solvent free crystal structures of polymorphs 1 and 2, and these are reported together with the structures of 10 solvates. Both polymorphs contain voids. Polymorph 1 is more stable has a higher density and a smaller void than polymorph 2 but also has unused hydrogen bonding capacity. The solvates exhibit a range of different hydrogen bonding networks and have no voids. Some of the structures have both tautomers of stanozolol present in the asymmetric unit.