title: Structural and Physicochemical Studies of Olopatadine Hydrochloride Conformational Polymorphs.
abstract: Crystal and molecular structures of 2 conformational polymorphs (forms I and II) of olopatadine hydrochloride, an antiallergic agent, are presented. Both crystal modifications crystallize in the monoclinic crystal system with 1 olopatadine hydrochloride molecule in the Z configuration in the asymmetric unit. Molecules are arranged into the centrosymmetric association through the interactions of the intermolecular strong and weak hydrogen bonds of N-H…Cl, O-H…Cl and C-H…Cl, C-H…O types. Conformational change between polymorphs is proved by calculations of a maximum torsion angle deviation (max[Δθ]) and a root-mean-square deviation between the atomic positions (rmsd[r]). The physicochemical characterization of polymorphs is performed by X-ray powder diffraction, infrared and Raman spectroscopy, differential scanning calorimetry. The comparison of the melting points and heats of fusions shows that the forms are monotropically related.
authors.affiliation: Pharmaceutical Research Institute (PRI), 8 Rydygiera Street, Warsaw 01-793, Poland. Electronic address: m.laszcz@ifarm.eu.
authors.forename: Marta
authors.initials: M
authors.lastname: Łaszcz
authors.affiliation: Pharmaceutical Research Institute (PRI), 8 Rydygiera Street, Warsaw 01-793, Poland.
authors.forename: Kinga
authors.initials: K
authors.lastname: Trzcińska
authors.affiliation: Pharmaceutical Research Institute (PRI), 8 Rydygiera Street, Warsaw 01-793, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Witkowska
authors.affiliation: Pharmaceutical Research Institute (PRI), 8 Rydygiera Street, Warsaw 01-793, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Ciesielska
authors.affiliation: Pharmaceutical Research Institute (PRI), 8 Rydygiera Street, Warsaw 01-793, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Badowska-Rosłonek
authors.affiliation: Pharmaceutical Research Institute (PRI), 8 Rydygiera Street, Warsaw 01-793, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kuziak
mesh_terms: D065966:Absorption, Physicochemical; D018926:Anti-Allergic Agents / Q000737:chemistry*; D003460:Crystallization; D008956:Models, Chemical; D015394:Molecular Structure; D000069605:Olopatadine Hydrochloride / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D018926:Anti-Allergic Agents; D012997:Solvents; D014867:Water; D000069605:Olopatadine Hydrochloride
keywords: Raman spectroscopy; X-ray diffractometry; calorimetry; crystallization; crystallography; hygroscopicity; infrared spectroscopy; physicochemical; polymorphism; stability