A crystalline LNnT polymorph IV, characterized in that it displays X-ray powder diffraction reflections, based on a measurement using CuKα radiation, at 8.16, 15.41, 39.14, 23.77, 7.77 and 31.15 2Θ angles, and a crystalline LNnT polymorph V, characterized in that it displays X-ray powder diffraction reflections, based on a measurement using CuKα radiation, at 9.15, 10.26, 19.68, 26.06, 20.61 and 1 1.89 2Θ angles, are provided.