title: ¹⁴N nuclear quadrupole resonance study of polymorphism in famotidine.
abstract: (14)N nuclear quadrupole resonance (NQR) in two known polymorphs of famotidine was measured. At room temperature, seven quadrupolar sets of transition frequencies (ν(+), ν(-), and ν(0)) corresponding to seven different nitrogen sites in the crystal structure of each of the two polymorphs were found. This confirms the expected ability of NQR to distinguish polymorph B from its analog A. NQR can also measure their ratio in a solid mixture and in the final dosage form, that is, a tablet. The NQR frequencies, line shapes, and tentative assignation to all seven molecular (14)N atoms were obtained. Unravelment of these two entangled NQR spectra presents a valuable contribution to the NQR database and enables studies of some possible correlations therein. Moreover, nondestructive (14)N NQR studies of commercial famotidine tablets can reveal some details of the drug fabrication process connected with compression.
authors.affiliation: Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia.
authors.forename: Janko
authors.initials: J
authors.lastname: Luźnik
authors.affiliation: Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia. Electronic address: janez.prnat@imfm.si.
authors.forename: Janez
authors.initials: J
authors.lastname: Pirnat
authors.affiliation: Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia.
authors.forename: Vojko
authors.initials: V
authors.lastname: Jazbinšek
authors.affiliation: Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Lavrič
authors.affiliation: Institute J. Stefan, Ljubljana, Slovenia.
authors.forename: Veselko
authors.initials: V
authors.lastname: Žagar
authors.affiliation: Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Stane
authors.initials: S
authors.lastname: Srčič
authors.affiliation: Institute J. Stefan, Ljubljana, Slovenia.
authors.forename: Janez
authors.initials: J
authors.lastname: Seliger
authors.affiliation: Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia.
authors.forename: Zvonko
authors.initials: Z
authors.lastname: Trontelj
mesh_terms: D015738:Famotidine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009584:Nitrogen / Q000737:chemistry*; D013607:Tablets / Q000737:chemistry; D013696:Temperature
chemical_list: D013607:Tablets; D015738:Famotidine; D009584:Nitrogen
keywords: analysis; crystal polymorphism; crystal structure; database; polymorphism; solid-state NMR; spectroscopy; tableting