Structural multiplicity in a solvated hydrate of the antiretroviral protease inhibitor Lopinavir

Lopinavir is a potent protease inhibitor that is used as a first-line pharmaceutical drug for the treatment of HIV. The multi-component solvated Lopinavir crystal, systematic name (2S)-N-[(2S,4S,5S)-5-[2-(2,6-dimethylphenoxy)acetamido]-4-hydroxy-1,6-diphenylhexan-2-yl]-3-methyl-2-(2-oxo-1,3-diazinan-1-yl)butanamide-ethane-1,2-diol-water (8/3/7) 8C₃₇H₄₈N₄O₅·3C₂H₆O₂·7H₂O, was prepared using evaporative methods. The crystalline material obtained from this experimental synthesis was characterized and elucidated by single-crystal X-ray diffraction (SC-XRD). The crystal structure is unusual in that the unit cell contains 18 molecules. The stoichiometric ratio of this crystal is eight Lopinavir molecules [8(C₃₇H₄₈N₄O₅)], three ethane-1,2-diol molecules [3(C₂H₆O₂)] and seven water molecules [7(H₂O)]. The crystal packing features both bi- and trifurcated hydrogen bonds between atoms.