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artículo con referato
"Aging-driven decomposition in zolpidem hemitartrate hemihydrate and the single-crystal structure of its decomposition products"
D.R. Vega, R. Baggio, M. Roca and D. Tombari
J. Pharm. Sci. 100(4) (2011) 1377-1386
The “aging-driven” decomposition of zolpidem hemitartrate hemihydrate (form A) has been followed by X-ray powder diffraction (XRPD), and the crystal and molecular structures of the decomposition products studied by single-crystal methods. The process is very similar to the “thermally driven” one, recently described in the literature for form E (Halasz and Dinnebier. 2010. J Pharm Sci 99(2): 871-874), resulting in a two-phase system: the neutral free base (common to both decomposition processes) and, in the present case, a novel zolpidem tartrate monohydrate, unique to the “aging-driven” decomposition. Our room-temperature single-crystal analysis gives for the free base comparable results as the high-temperature XRPD ones already reported by Halasz and Dinnebier: orthorhombic, Pcba, a = 9.6360(10) Å, b = 18.2690(5) Å, c = 18.4980(11) Å, and V = 3256.4(4) Å3. The unreported zolpidem tartrate monohydrate instead crystallizes in monoclinic P21, which, for comparison purposes, we treated in the nonstandard setting P1121 with a = 20.7582(9) Å, b = 15.2331(5) Å, c = 7.2420(2) Å, y = 90.826(2)°, and V = 2289.73(14) Å3. The structure presents two complete moieties in the asymmetric unit (z = 4, z′ = 2). The different phases obtained in both decompositions are readily explained, considering the diverse genesis of both processes.
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