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Salts of active pharmaceutical ingredients (APIs) have been traditionally used in drug formulations because of improved properties with respect to solubility, stability, or bioavailability. Saccharin has been used as an acid for salt formation with APIs in a few cases hitherto. In this paper, we have explored the generality of this property and have isolated saccharinates of quinine, haloperidol, mirtazapine, pseudoephedrine, lamivudine, risperidone, sertraline, venlafaxine, zolpidem, and amlodipine. These salts have been characterized with single-crystal X-ray methods. The structures contain many hydrogen bonds of the O−H···N(-), N(+)-H···N(-), N(+)−H···O, N−H···O, O−H···O and N−H···N type, with auxiliary C−H···N(-) and C−H···O interactions. These saccharinates are mostly very soluble in water when compared to the free base. Additionally, aqueous solutions of these API saccharinates are of moderate pH. Both these properties may be advantageous in the pharmaceutical industry. In general, most saccharinate...

In the crystal structure of the title compound [systematic name: 1-ethyl-6-fluoro-4-oxo-7-(piperazin-4-ium-1-yl)-1,4-dihydroquinoline-3-carboxylate sesquihydrate], C16H18FN3O3·1.42H2O, N—H...O and O—H...O hydrogen bonds assemble the molecules in a two-dimensional layered corrugated sheet structure parallel to the b axis. The water molecules are disordered [occupancies 0.741 (11) and 0.259 (11)].

In the crystal structure of the title compound, 2C5H5N4O+·SO42−, N—H...O hydrogen bonds assemble the molecules into a two-dimensional network structure parallel to the cb plane. The S atom of the sulfate ion lies on a special position on a twofold axis.

Saccharin, acting as a weak acid, forms salts with basic APIs and these salts have the desirable property of enhanced water solubility.