Levothyroxine sodium pentahydrate (marketed as Synthroid) is a synthetic form of the thyroid hormone, thyroxine, which is used in the treatment of thyroid hormone deficiency. Commercial levothyroxine sodium pentahydrate crystallizes in the triclinic space group P1 (#1), with a = 8.2489(4) Å, b = 9.4868(5) Å, c = 15.8298(6) Å, α = 84.1387(4)°, β = 83.1560(3)°, γ = 85.0482(3)°, V = 1220.071(9) Å3, and Z = 2. A reduced cell search in the Cambridge Structural Database yielded a previously reported crystal structure (Allen, Reference Allen2002), which did not include hydrogens (Katrusiak et al., Reference Katrusiak and Katrusiak2004). In this work, the sample was ordered from United States Pharmacopeia, and analyzed as received. The room-temperature crystal structure was refined using synchrotron (λ = 0.413 891 Å) powder diffraction data, density functional theory, and Rietveld refinement techniques. Hydrogen positions were included as part of the structure, and recalculated during the refinement. The diffraction data were collected on beamline 11-BM at the Advanced Photon Source, Argonne National Laboratory. Figure 1 shows the powder X-ray diffraction pattern of the compound.
Figure 1. (Color online) Powder X-ray diffraction pattern of levothyroxine sodium pentahydrate.
SUPPLEMENTARY MATERIALS
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ACKNOWLEDGEMENTS
Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This work was partially supported by the International Centre for Diffraction Data. The authors thank Lynn Ribaud for his assistance in data collection.
