Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs

DSC, dielectric spectroscopy, and optical microscopy, are employed to analyze the equilibrium and out-of-equilibrium binary phase diagram of two antifungal azole compounds, fluconazole (FLZ) and econazole (ECZ), to study the physical stability of co-amorphous formulations that may allow co-administr...

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Autores: Noor, Wahi, Romanini, Michela|||0000-0002-1685-855X, Villalobos Ramos, Laia, Talukder, Bijori, Tamarit Mur, José Luis|||0000-0002-7965-0000, Macovez, Roberto|||0000-0001-5026-9372
Tipo de recurso: artículo
Fecha de publicación:2026
País:España
Institución:Universitat Politècnica de Catalunya (UPC)
Repositorio:UPCommons. Portal del coneixement obert de la UPC
Idioma:inglés
OAI Identifier:oai:dnet:upcommonspor::ffeeda7d426484d34c788b812a25cfb1
Acceso en línea:https://hdl.handle.net/2117/460708
https://dx.doi.org/10.1016/j.ijpx.2026.100525
Access Level:acceso abierto
Palabra clave:Amorphous solid solutions
Glass transition temperature
Eutectic amorphous mixtures
Relaxation dynamics
Physical stability of glasses
Formulation pre-development
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dc.title.none.fl_str_mv Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
title Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
spellingShingle Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
Noor, Wahi
Amorphous solid solutions
Glass transition temperature
Eutectic amorphous mixtures
Relaxation dynamics
Physical stability of glasses
Formulation pre-development
title_short Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
title_full Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
title_fullStr Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
title_full_unstemmed Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
title_sort Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIs
dc.creator.none.fl_str_mv Noor, Wahi
Romanini, Michela|||0000-0002-1685-855X
Villalobos Ramos, Laia
Talukder, Bijori
Tamarit Mur, José Luis|||0000-0002-7965-0000
Macovez, Roberto|||0000-0001-5026-9372
author Noor, Wahi
author_facet Noor, Wahi
Romanini, Michela|||0000-0002-1685-855X
Villalobos Ramos, Laia
Talukder, Bijori
Tamarit Mur, José Luis|||0000-0002-7965-0000
Macovez, Roberto|||0000-0001-5026-9372
author_role author
author2 Romanini, Michela|||0000-0002-1685-855X
Villalobos Ramos, Laia
Talukder, Bijori
Tamarit Mur, José Luis|||0000-0002-7965-0000
Macovez, Roberto|||0000-0001-5026-9372
author2_role author
author
author
author
author
dc.subject.none.fl_str_mv Amorphous solid solutions
Glass transition temperature
Eutectic amorphous mixtures
Relaxation dynamics
Physical stability of glasses
Formulation pre-development
topic Amorphous solid solutions
Glass transition temperature
Eutectic amorphous mixtures
Relaxation dynamics
Physical stability of glasses
Formulation pre-development
description DSC, dielectric spectroscopy, and optical microscopy, are employed to analyze the equilibrium and out-of-equilibrium binary phase diagram of two antifungal azole compounds, fluconazole (FLZ) and econazole (ECZ), to study the physical stability of co-amorphous formulations that may allow co-administration and a faster dissolution of the poorly soluble ECZ compound. The two crystalline APIs form a eutectic equilibrium phase diagram with eutectic point at Te = 351.1 ± 0.5 K and eutectic molar fraction of FLZ of xFLZ,e = 0.22 ± 0.01. While amorphous FLZ has a strong tendency to crystallize, amorphous ECZ is kinetically stable during at least several weeks even as a supercooled liquid. Amorphous ECZ is found to display faster kinetic dissolution profile in water compared with crystalline ECZ. The glass transition (Tg) of the liquid mixtures depends linearly on composition, increasing by 4 K for every 10% increase in xFLZ. The molecular mobility determined by dielectric spectroscopy is characterized by a single structural relaxation and a single Johari-Goldstein relaxation at all compositions, testifying the structural and dynamic homogeneity of the amorphous mixtures. The equimolar supercooled liquid mixture and FLZ-rich mixtures phase-separate over few days or weeks, with the FLZ-rich phase recrystallizing into bundles of rod-like crystallites surrounded by an almost pure amorphous ECZ matrix. The amorphous mixture at the eutectic composition remains instead kinetically stable during 6 months above Tg, and for at least 10 months in the glass state below Tg. Mixtures that have ECZ molar fractions of 0.9 or higher are kinetically the most stable ones (they remain amorphous during more than 14 months at room temperature) despite having the fastest molecular mobility both in the supercooled liquid and glassy phases. Their high kinetic stability is likely due to lower supercooling and lower supersaturation, leading to lower thermodynamic driving force, and to the dilution of the recrystallizing FLZ compound. These results help shed light on the stability of binary amorphous mixtures.
publishDate 2026
dc.date.none.fl_str_mv 2026
2026-06-01
2026
2026-04-17
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/2117/460708
https://dx.doi.org/10.1016/j.ijpx.2026.100525
url https://hdl.handle.net/2117/460708
https://dx.doi.org/10.1016/j.ijpx.2026.100525
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.relation.none.fl_str_mv Agencia Estatal de Investigación http://doi.org/10.13039/501100011033 Plan Estatal de Investigación Científica y Técnica y de Innovación 2021-2023 PID2023-146623NB-I00 ABORDANDO EL DESORDEN: LA FISICA EN EL APROVECHAMIENTO DE LA ENERGIA
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial-NoDerivatives 4.0 International
http://creativecommons.org/licenses/by-nc-nd/4.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial-NoDerivatives 4.0 International
http://creativecommons.org/licenses/by-nc-nd/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Elsevier
publisher.none.fl_str_mv Elsevier
dc.source.none.fl_str_mv reponame:UPCommons. Portal del coneixement obert de la UPC
instname:Universitat Politècnica de Catalunya (UPC)
instname_str Universitat Politècnica de Catalunya (UPC)
reponame_str UPCommons. Portal del coneixement obert de la UPC
collection UPCommons. Portal del coneixement obert de la UPC
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spelling Metastable phase diagram, mobility, and kinetic stability of amorphous mixtures of two mutually compatible APIsNoor, WahiRomanini, Michela|||0000-0002-1685-855XVillalobos Ramos, LaiaTalukder, BijoriTamarit Mur, José Luis|||0000-0002-7965-0000Macovez, Roberto|||0000-0001-5026-9372Amorphous solid solutionsGlass transition temperatureEutectic amorphous mixturesRelaxation dynamicsPhysical stability of glassesFormulation pre-developmentDSC, dielectric spectroscopy, and optical microscopy, are employed to analyze the equilibrium and out-of-equilibrium binary phase diagram of two antifungal azole compounds, fluconazole (FLZ) and econazole (ECZ), to study the physical stability of co-amorphous formulations that may allow co-administration and a faster dissolution of the poorly soluble ECZ compound. The two crystalline APIs form a eutectic equilibrium phase diagram with eutectic point at Te = 351.1 ± 0.5 K and eutectic molar fraction of FLZ of xFLZ,e = 0.22 ± 0.01. While amorphous FLZ has a strong tendency to crystallize, amorphous ECZ is kinetically stable during at least several weeks even as a supercooled liquid. Amorphous ECZ is found to display faster kinetic dissolution profile in water compared with crystalline ECZ. The glass transition (Tg) of the liquid mixtures depends linearly on composition, increasing by 4 K for every 10% increase in xFLZ. The molecular mobility determined by dielectric spectroscopy is characterized by a single structural relaxation and a single Johari-Goldstein relaxation at all compositions, testifying the structural and dynamic homogeneity of the amorphous mixtures. The equimolar supercooled liquid mixture and FLZ-rich mixtures phase-separate over few days or weeks, with the FLZ-rich phase recrystallizing into bundles of rod-like crystallites surrounded by an almost pure amorphous ECZ matrix. The amorphous mixture at the eutectic composition remains instead kinetically stable during 6 months above Tg, and for at least 10 months in the glass state below Tg. Mixtures that have ECZ molar fractions of 0.9 or higher are kinetically the most stable ones (they remain amorphous during more than 14 months at room temperature) despite having the fastest molecular mobility both in the supercooled liquid and glassy phases. Their high kinetic stability is likely due to lower supercooling and lower supersaturation, leading to lower thermodynamic driving force, and to the dilution of the recrystallizing FLZ compound. These results help shed light on the stability of binary amorphous mixtures.We acknowledge support from the Spanish Ministry of Science, Innovation and Universities under the “María deMaeztu” Program for Units of Excellence (Grant No. CEX2023-001300-M). This work was funded by the same Ministry under Grant No. MCIN/AEI/10.13039/ 501100011033, and under Project No. PID2023-146623NB-I00, cofi- nanced also by the European Union European Regional Development Fund (FEDER). We acknowledge support from the Generalitat de Cata- lunya (Grant No. 2021SGR-00343). J.-Ll. Tamarit is grateful to the ICREA Academia program. M. Romanini is a Serra Húnter fellow. The authors are grateful to Lourdes Franco of the Universitat Politècnica de Catalunya - BarcelonaTech for her help with microscopy experiments.Elsevier20262026-06-0120262026-04-17journal articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/2117/460708https://dx.doi.org/10.1016/j.ijpx.2026.100525reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)InglésengAgencia Estatal de Investigación http://doi.org/10.13039/501100011033 Plan Estatal de Investigación Científica y Técnica y de Innovación 2021-2023 PID2023-146623NB-I00 ABORDANDO EL DESORDEN: LA FISICA EN EL APROVECHAMIENTO DE LA ENERGIAopen accesshttp://purl.org/coar/access_right/c_abf2Attribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/openAccessoai:dnet:upcommonspor::ffeeda7d426484d34c788b812a25cfb12026-05-27T15:37:01Z
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