Elucidating the crystal structure of the antimalarial drug (+/-)-mefloquine hydrochloride: a tetragonal hydrated species

Abstract

Albeit widely studied, the structure of the antimalarial drug (+/-)-mefloquine hydrochloride is still a controversial issue. A combination of X-ray powder diffraction, theoretical calculations and Fourier transform-infrared spectroscopy is used to unambiguously determine the crystal structure of the molecule in its active pharmaceutical ingredient. It is demonstrated that water is incorporated into the structure, leading to a hydrated form and, most importantly, to significant differences in both structure and bonding. Such changes can lead to significant differences in biological activity. (C) 2014 International Union of Crystallography