title: The relative stability of xylazine hydrochloride polymorphous forms.
abstract: All four known xylazine hydrochloride polymorphous forms were obtained and their relative stabilities were compared directly at three different temperatures. At higher temperatures, it is possible to determine the relative stability of all forms directly by measuring the changes in the composition of the mixtures of two polymorphous forms using powder x-ray diffraction methods. At lower temperatures, a solvent was added to the mixture and the changes in composition were determined. Polymorph transition temperatures were determined directly. To predict the transition temperature which was not found using the direct method, the polymorph melting data and determined transition temperatures were used. A phase stability diagram was constructed from the acquired data. The stability of all anhydrous polymorphous forms was compared in the presence of water vapor pressure that was higher than the equilibrium pressure.
authors.affiliation: Faculty of Chemistry, University of Latvia, Rīga, Latvia. agris86@inbox.lv
authors.forename: Agris
authors.initials: A
authors.lastname: Bērziņs
authors.forename: Kristīne
authors.initials: K
authors.lastname: Krūkle
authors.forename: Andris
authors.initials: A
authors.lastname: Actiņs
authors.forename: Juris P
authors.initials: JP
authors.lastname: Kreismanis
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000737:chemistry*; D003460:Crystallization; D004355:Drug Stability; D012997:Solvents / Q000737:chemistry*; D013696:Temperature; D044366:Transition Temperature; D055548:Vapor Pressure; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction; D014991:Xylazine / Q000737:chemistry*
chemical_list: D000316:Adrenergic alpha-Agonists; D012997:Solvents; D014867:Water; D014991:Xylazine