Furosemide Cocrystals: Structures, Hydrogen Bonding, and Implications for Properties

Abstract

In this paper, we report the crystal growth of four cocrystals of furosemide (4-chloro-2-[(2-furanylmethyl)amino]-5-sulfamoylbenzoic acid), a loop diuretic drug used for the treatment of hypertension and edemas, prepared with p-aminobenzoic acid, nicotinamide, and isonicotinamide as coformers. We present four new crystal structures and elucidate the intermolecular interactions present in the cocrystals. The structures display interesting supramolecular chemistry: a number of different synthons, as well as short strong hydrogen bonds with partial proton transfer and indications of proton disorder. Using powder X-ray diffraction, solid state NMR, and thermal analysis, we provide evidence for the preparation of bulk samples of two compositions, namely, the 1:1 cocrystal of furosemide and p-aminobenzoic acid and 2:1 cocrystal of furosemide and isonicotinamide, highlighting the general necessity of such multitechnique approaches to characterize organic solids (including cocrystals and solvates) prepared by gri...