Aging-driven decomposition in zolpidem hemitartrate hemihydrate and the single-crystal structure of its decomposition products

✍ Scribed by Daniel R. Vega; Ricardo Baggio; Mariana Roca; Dora Tombari

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 618 KB
• Volume: 100
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.22358

✦ Synopsis

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) Å 3 . The unreported zolpidem tartrate monohydrate instead crystallizes in monoclinic P2 1 , which, for comparison purposes, we treated in the nonstandard setting P112 1 with a = 20.7582(9) Å, b = 15.2331(5) Å, c = 7.2420(2) Å, γ = 90.826(2) • , and V = 2289.73(14) Å 3 . 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.