title: Solid-state NMR and IR for the analysis of pharmaceutical solids: polymorphs of fosinopril sodium.
abstract: The two polymorphic modifications of fosinopril sodium have been characterized as to their differences in melting behaviour, powder X-ray diffraction patterns, Fourier transform infrared spectra (FTIR), and solid-state 31P- and 13C-NMR spectra. The polymorphs were found to be enantiotropically related based upon melting point, heat of fusion, and solution mediated transformation data. Analysis of the solid-state FTIR and 13C-NMR data indicated that the environment of the acetal side chain of fosinopril sodium differed in two polymorphs, and that there might be cis-trans isomerization about the C6-N peptide bond. These conformational differences are postulated as the origin of the observed polymorphism.
authors.affiliation: Bristol-Myers Squibb Pharmaceutical Research Institute, New Brunswick, NJ 08903.
authors.forename: H G
authors.initials: HG
authors.lastname: Brittain
authors.forename: K R
authors.initials: KR
authors.lastname: Morris
authors.forename: D E
authors.initials: DE
authors.lastname: Bugay
authors.forename: A B
authors.initials: AB
authors.lastname: Thakur
authors.forename: A T
authors.initials: AT
authors.lastname: Serajuddin
mesh_terms: D003460:Crystallization; D017328:Fosinopril / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D014961:X-Ray Diffraction
chemical_list: D017328:Fosinopril