title: The effect of excipients on the stability and phase transition rate of xylazine hydrochloride and zopiclone.
abstract: The compatibility of thermodynamically unstable polymorph of two active pharmaceutical compounds (xylazine hydrochloride form X and zopiclone form C) with different excipients was investigated. The effects of the excipient and its amount in the sample on the thermal properties and possible chemical interactions were studied. The most commonly used excipients in the pharmaceutical industry - calcium carbonate, lactose hydrate, cellulose, magnesium stearate hydrate and calcium stearate hydrate were selected for this study. The dependence of the phase transition rate from an unstable to a more stable polymorph on the excipients and their amounts in the initial sample was analysed at 80°C, and the corresponding phase transition rate constants were calculated.
authors.affiliation: Faculty of Chemistry, University of Latvia, Kr. Valdemara iela 48, LV-1013 Riga, Latvia. Electronic address: kristine.krukle-berzina@lu.lv.
authors.forename: Kristīne
authors.initials: K
authors.lastname: Krūkle-Bērziņa
authors.affiliation: Faculty of Chemistry, University of Latvia, Kr. Valdemara iela 48, LV-1013 Riga, Latvia.
authors.forename: Andris
authors.initials: A
authors.lastname: Actiņš
mesh_terms: D053961:Azabicyclo Compounds / Q000737:chemistry*; D004345:Drug Industry / Q000379:methods; D004355:Drug Stability; D005079:Excipients / Q000737:chemistry*; D007700:Kinetics; D044367:Phase Transition; D010879:Piperazines / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014991:Xylazine / Q000737:chemistry*
chemical_list: D053961:Azabicyclo Compounds; D005079:Excipients; D010879:Piperazines; C515050:zopiclone; D014991:Xylazine
keywords: Excipients; Phase transition kinetics; Polymorphs; Stability; Thermal properties