14N Nuclear Quadrupole Resonance Study of Polymorphism in Famotidine

14N nuclear quadrupole resonance (NQR) in two known polymorphs of famotidine was measured. At room temperature, seven quadrupolar sets of transition frequencies (ν+, ν−, and ν0) 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 14N 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 14N NQR studies of commercial famotidine tablets can reveal some details of the drug fabrication process connected with compression. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:2704–2709, 2014