title: A cross-polarization magic-angle spinning 13C NMR characterization of the stable solid-state forms of cimetidine.
abstract: Proton decoupled, cross-polarization magic-angle spinning 13C NMR spectra of four polymorphic forms (A, B, C, and D) and a monohydrate form (M1) of the histamine H2 antagonist cimetidine were obtained, and the chemical shifts of the various forms were tabulated. A modified polarization inversion pulse sequence was used to distinguish quaternary, methine, methylene, and methyl carbon resonances and thereby assist spectral assignment. It is also shown that the solid-state form of cimetidine in a commercial formulation can be reliably ascertained by NMR, despite the presence in the spectrum of signals from organic excipients that are much more intense than those from the compound.
authors.affiliation: Analytical Sciences Department, SmithKline Beecham Pharmaceuticals, Welwyn, Herts., Great Britain.
authors.forename: D A
authors.initials: DA
authors.lastname: Middleton
authors.forename: C S
authors.initials: CS
authors.lastname: Le Duff
authors.forename: F
authors.initials: F
authors.lastname: Berst
authors.forename: D G
authors.initials: DG
authors.lastname: Reid
mesh_terms: D002247:Carbon Isotopes; D002927:Cimetidine / Q000737:chemistry*; D003460:Crystallization; D005079:Excipients; D006635:Histamine H2 Antagonists / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D005079:Excipients; D006635:Histamine H2 Antagonists; D002927:Cimetidine