0000000000369566
AUTHOR
Kristīne Krūkle-bērziņa
showing 8 related works from this author
The effect of excipients on the stability and phase transition rate of xylazine hydrochloride and zopiclone
2015
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 …
Investigation of the phase transitions occurring during and after the dehydration of xylazine hydrochloride monohydrate.
2014
This paper reports an investigation of a complex solid state phase transition where two inter-converting polymorphs (X and A) of the pharmaceutical molecule xylazine hydrochloride formed and transformed during and after the dehydration of its monohydrate (H). The crystal structures of all three forms were compared. During the investigation of this solid state phase transition it was determined that the dehydration of H produced either a pure X form, or a mixture of the X and A forms. The phase composition depended on the sample preparation procedure and the experimental conditions. It was found that grinding of the hydrate enhanced the formation of polymorph X as a product of dehydration, w…
Powder X-Ray Diffraction Investigation of Xylazine Hydrochloride Solid Phase Transformation Kinetics
2013
The kinetics of the solid-state phase transformation of xylazine hydrochloride form X to A has been investigated using powder X-ray diffraction and differential thermal analysis. Three different kinetic models have been used to describe transition kinetics: the Avrami–Erofeev equation, the Cardew equation, and the methodology for simulation of solid-state phase transition kinetics by the combination of nucleation and nuclei growth processes. The latter has been recently developed and has been tested in this paper for the case of a real solid-state transition. The relative humidity, mechanical pressure, temperature, and sample-preparation effect on phase-transition kinetics have been investi…
The Preparation and Characterization of New Antazoline Salts with Dicarboxylic Acids
2015
New antazoline salts with organic acids (fumaric acid, oxalic acid, and maleic acid) were prepared. The effect of the crystallization solvent and mechanochemical treatment on the crystalline forms of these salts was studied. Two polymorphs of antazoline hydrogen maleate were identified and their relative stability was determined. The molecular structures of antazoline hydrogen oxalate and antazoline hydrogen maleate showed differences in antazoline cation conformation. In crystal structures of all salts both imidazoline nitrogens of antazoline cation are involved in hydrogen bond formation with carboxyl groups of the acid.
Modelling IR Spectra of Sulfonated Polyether Ether Ketone (SPEEK) Membranes for Fuel Cells
2020
Authors acknowledge support from LSC project No 2014/666 ERDF and students ( ) support from project 2DP/2.1.1.1.0/14/APIA/VIAA/009.
Understanding complex phase transition mechanism by crystal structure analysis
2014
Xylazine hydrochloride (2-(2,6-xylidino)-5,6-dihydro-4H-1,3-thiazine hydrochloride) is an adrenergic α-agonist used as a sedative, analgesic, and muscle relaxant in veterinary medicine. It has four polymorphous forms (A, Z, M and X), monohydrate (H), hemihydrate and solvates with dichloromethane and 2-propanol. It has been reported that the polymorph X is thermodynamically the least stable of these polymorphs, while the A is the most stable form at temperatures above 500C. The X forms only in H dehydration process, and at elevated temperature X transforms to polymorph A [1]. The crystal structures of the polymorphs A and X as well as hydrate H have been reported. Crystal structure of A and …
Apstrādes, izturēšanas apstākļu un blakus vielu ietekme uz farmaceitiski aktīvo cietvielu fāžu pārejām
2015
Elektroniskā versija nesatur pielikumus
Ksilazīna hidrogēnhlorīda stabilitāte un fāžu pāreju kinētika
2009
Bakalaura darba teorētiskajā daļā dots ksilazīna hidrogēnhlorīda raksturojums, cieto fāžu iedalījums, polimorfo formu termodinamika un cietās fāzes kinētika. Aplūkotas polimorfo formu pētīšanas metodes un kvantitatīvā fāžu analīze ar rentgendifraktometriju. Eksperimentālajā daļā ksilazīna hidrogēnhlorīda polimorfiem noskaidrota savstarpējā stabilitāte un atrastas līdzsvara temperatūras. Pielāgota kvantitatīvās analīzes metode A un X maisījuma sastāva noteikšanai kinētikas pētījumiem. Pētīta dažādu fizikālu faktoru ietekme uz X formas pāreju par A formu. Šī procesa kinētiskā līkne tuvināti aprakstīta ar integrālvienādojumu. A, Z un M formām uzņemtas hidratācijas līknes dažādos apstākļos, pie…