Solid state investigation of mefloquine hydrochloride

Abstract Mefloquine hydrochloride was crystallized under different conditions and the products were studied by thermal analysis, IR spectroscopy and X-ray diffraction. It was demonstrated that different conditions of crystallization resulted in different crystal structures. The α- and δ-modifications were hydrates, the gb- and γ-forms were polymorphs, the ϵ-form was an acetone solvate and θ-mefloquine was tetrahydrofuran solvate. During long storage at room temperature, the α-, δ- and θ-forms of mefloquine hydrochloride were transformed. By heat treatment of the δ-, ϵ and θ-modifications, a new crystal structure was obtained.