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44 results on '"Barbas, Rafael"'

5. An experimental and computational investigation of the elusive anhydrous form of Oxyma-B.

Author

Prohens, Rafel, Barbas, Rafael, de la Torre, Beatriz G., Albericio, Fernando, and Frontera, Antonio

Subjects
*X-ray powder diffraction, *QUANTUM theory, *PEPTIDE synthesis, *CRYSTAL growth, *CRYSTAL structure
Abstract

We report the crystal structure of the anhydrous form of Oxyma-B, a relevant racemization suppressor for peptide synthesis, solved by direct space methodologies with X-Ray Powder Diffraction data. The structure had remained elusive since only monohydrate crystals are readily obtained from slow crystal growth experiments. An extensive combined experimental and computational study has allowed us to obtain deeper insight into the solid-state landscape of Oxyma-B and its tendency for hydration. The singular network of H-bonds and energetically relevant O⋯π interactions formed by the two symmetrically independent molecules of anhydrous Oxyma-B has been analysed by using the quantum theory of "atoms-in-molecules" (QTAIM) and the noncovalent interaction plot (NCIplot). [ABSTRACT FROM AUTHOR]

Published
2023
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15. Novel Polymorphic Cocrystals of the Non-Steroidal Anti-Inflammatory Drug Niflumic Acid: Expanding the Pharmaceutical Landscape

Author

Acebedo-Martínez, Francisco Javier, primary, Alarcón-Payer, Carolina, additional, Frontera, Antonio, additional, Barbas, Rafael, additional, Prohens, Rafel, additional, Di Crisci, Milena, additional, Domínguez-Martín, Alicia, additional, Gómez-Morales, Jaime, additional, and Choquesillo-Lazarte, Duane, additional

Published
2021
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16. Alternativas para el aprovechamiento de los residuos de poda del arbolado urbano de Valledupar según su impacto en el inventario del ciclo de vida

Author

García Barbas, Rafael Augusto and Pacheco Bustos, Carlos

Subjects
Árboles -- Poda -- Valledupar (Colombia)
Abstract

Valledupar es admirado por sus visitantes no solo por su música y el festival de la leyenda vallenata, sino también por el verde de sus árboles presentes en sus calles, avenidas y los frentes de las viviendas. Se estima que la ciudad cuenta con más de 70.000 árboles donde la gran mayoría de sus especies con nombres comunes como: árbol de Mango, Caucho y Uva Venezolana entre otros. La generación y gestión de residuos urbanos es considerado un problema global crítico, y un problema medioambiental frecuentemente no reconocido que gira en torno a la generación de residuos urbanos, afectando también a la ciudad de Valledupar. En el presente estudio se busca elaborar el análisis entre algunas alternativas de transformación de residuos de poda del arbolado urbano de Valledupar mediante la Evaluación del Ciclo de Vida de cada uno de los procesos de transformación dispuestos en esta investigación, con la finalidad de proponer una estrategia que aporte al desarrollo sostenible, cuidado del medio ambiente y bienestar social de la comunidad. Obteniendo así la información necesaria para identificar problemáticas e impactos ambientales, para de esta manera analizar la información de alternativas de gestión existentes, y de igual forma evaluar el ciclo de vida y cada uno de los procesos identificados, mediante una metodología aplicada de análisis de datos a cada uno de los procesos propuestos para la transformación de residuos de poda del arbolado de Valledupar, llegando así aplicar un análisis de ciclo de vida (ACV), con la utilización del software OPENLCA. Maestría Magister en Ingeniería Ambiental

Published
2021

17. Novel polymorphic cocrystals of the non-steroidal anti-inflammatory drug niflumic acid: Expanding the pharmaceutical landscape

Author

Ministerio de Ciencia, Innovación y Universidades (España), Universidad de Granada, Acebedo-Martínez, Francisco Javier, Alarcón-Payer, Carolina, Frontera, Antonio, Barbas, Rafael, Prohens, Rafel, Di Crisci, Milena, Domínguez-Martín, Alicia, Gómez Morales, Jaime, Choquesillo-Lazarte, Duane, Ministerio de Ciencia, Innovación y Universidades (España), Universidad de Granada, Acebedo-Martínez, Francisco Javier, Alarcón-Payer, Carolina, Frontera, Antonio, Barbas, Rafael, Prohens, Rafel, Di Crisci, Milena, Domínguez-Martín, Alicia, Gómez Morales, Jaime, and Choquesillo-Lazarte, Duane

Abstract

Any time the pharmaceutical industry develops a new drug, potential polymorphic events must be thoroughly described, because in a crystalline pharmaceutical solid, different arrangements of the same active pharmaceutical ingredient can yield to very different physicochemical properties that might be crucial for its efficacy, such as dissolution, solubility, or stability. Polymorphism in cocrystal formulation cannot be neglected, either. In this work, two different cocrystal polymorphs of the non-steroidal anti-inflammatory drug niflumic acid and caffeine are reported. They have been synthesized by mechanochemical methods and thoroughly characterized in solid-state by powder and single crystal X-ray diffraction respectively, as well as other techniques such as thermal analyses, infrared spectroscopy and computational methods. Both theoretical and experimental results are in agreement, confirming a conformational polymorphism. The polymorph NIF–CAF Form I exhibits improved solubility and dissolution rate compared to NIF–CAF Form II, although Form II is significantly more stable than Form I. The conditions needed to obtain these polymorphs and their transition have been carefully characterized, revealing an intricate system.

Published
2021

18. Combined computational/experimental investigation of new cocrystals of the drug bosentan.

Author

Barbas, Rafael, Portell, Anna, Hunter, Christopher A., Prohens, Rafel, and Frontera, Antonio

Subjects
*SUCCINIC acid, *ELECTRIC potential, *PULMONARY artery, *PULMONARY hypertension, *HOMODIMERS
Abstract

We report the discovery of new cocrystals of bosentan, a drug used in the treatment of pulmonary artery hypertension, with succinic acid, resorcinol, and 4-hydroxybenzoic acid through a combined virtual/experimental cocrystal screening. The X-ray structure of the bosentan/succinic acid cocrystal shows a network of H-bonds involving both components, which have been studied energetically using DFT calculations. The succinic acid molecules interact with one of the pyrazine rings of bosentan establishing an energetically significant lp⋯π interaction. Moreover, they form homodimers stabilized by antiparallel CO⋯CO interactions. This set of interactions has been rationalized using molecular electrostatic potential (MEP) surfaces, the quantum theory of "atoms-in-molecules" (QTAIM), and the noncovalent interaction plot (NCIplot). [ABSTRACT FROM AUTHOR]

Published
2022
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37. Morphotropism and “Quasi-Isostructurality” in the Three High Z′Concomitant Polymorphs of Efinaconazole

Author

Prohens, Rafel, Barbas, Rafael, and Font-Bardia, Mercè

Abstract

The crystal structures of the three efinaconazole anhydrous forms have been solved by single-crystal X-ray diffraction showing a very rare case of nearly isostructural polymorphism. The analysis of their crystal structures revealed that forms I and III are “quasi-isostructural” polymorphs and are morphotropically related to form II. The identical conformational and supramolecular environment can explain the concomitant polymorphism phenomenon observed for this important active pharmaceutical ingredient.

Published
2020
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42. Expanding the Crystal Form Landscape of the AntiviralDrug Adefovir Dipivoxil.

Author

Prohens, Rafel, Barbas, Rafael, Portell, Anna, Font-Bardia, Mercè, Alcobé, Xavier, and Puigjaner, Cristina

Subjects
*ADEFOVIR dipivoxil, *ANTIVIRAL agents, *SOLID state chemistry, *PRODRUGS, *SINGLE crystals, *X-ray diffraction
Abstract

The solid state of adefovir dipivoxil(AD) has been revisited.In the present article we extend the knowledge about the solid stateof this pharmaceutical prodrug. The stability landscape of the amorphousform with respect to the anhydrous and hydrate crystalline forms hasbeen studied, and the use of an antiplasticizing agent to increaseits Tg is described. The crystal structure of the elusive anhydrousform I has been determined from laboratory powder X-ray diffractiondata by means of direct space methods using the computing programFOX. In addition, three new isostructural solvates of AD (methanol,ethylenglycol, and methylethylketone) have been discovered and structurallycharacterized by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Published
2015
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43. Synthesis and Characterization of a New Norfloxacin/Resorcinol Cocrystal with Enhanced Solubility and Dissolution Profile.

Author

Fael, Hanan, Barbas, Rafael, Prohens, Rafel, Ràfols, Clara, and Fuguet, Elisabet

Subjects
*NORFLOXACIN, *RESORCINOL, *SOLUBILITY, *FLUOROQUINOLONES, *GASTROINTESTINAL system, *ANTIBIOTICS
Abstract

A new cocrystal of Norfloxacin, a poorly soluble fluoroquinolone antibiotic, has been synthetized by a solvent-mediated transformation experiment in toluene, using resorcinol as a coformer. The new cocrystal exists in both anhydrous and monohydrate forms with the same (1:1) Norfloxacin/resorcinol stoichiometry. The solubility of Norfloxacin and the hydrated cocrystal were determined by the shake-flask method. While Norfloxacin has a solubility of 0.32 ± 0.02 mg/mL, the cocrystal has a solubility of 2.64 ± 0.39 mg/mL, approximately 10-fold higher. The dissolution rate was tested at four biorelevant pH levels of the gastrointestinal tract: 2.0, 4.0, 5.5, and 7.4. In a first set of comparative tests, the dissolution rate of Norfloxacin and the cocrystal was determined separately at each pH value. Both solid forms showed the highest dissolution rate at pH 2.0, where Norfloxacin is totally protonated. Then, the dissolution rate decreases as pH increases. In a second set of experiments, the dissolution of the cocrystal was evaluated by a unique dissolution test, in which the pH dynamically changed from 2.0 to 7.4, stepping 30 min at each of the four biorelevant pH values. Results were quite different in this case, since dissolution at pH 2 affects the behavior of Norfloxacin at the rest of the pH values. [ABSTRACT FROM AUTHOR]

Published
2022
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44. Virtual Cocrystal Screening of Adefovir Dipivoxyl: Identification of New Solid Forms with Improved Dissolution and Permeation Profiles

Author

Rafael Barbas, Hanan Fael, Samuel Lee, Rebeca Ruiz, Christopher A. Hunter, Elisabet Fuguet, Clara Ràfols, Rafel Prohens, Barbas, Rafael [0000-0002-1603-3689], Hunter, Christopher A [0000-0002-5182-1859], Ràfols, Clara [0000-0001-7811-986X], Prohens, Rafel [0000-0003-0294-1720], and Apollo - University of Cambridge Repository

Subjects
Permeabilitat, Pharmaceutical Science, Polyphenols, Adefovir Dipivoxyl, polyphenols, cocrystal, cocrystallization, computational screening, dissolution rate, permeability, Permeability, Article, Polifenols
Abstract

Peer reviewed: True, Funder: Project PID2020–115374GB-100, Funder: Erasmus-Mundus Action-2 program, Avempace II project, from the European Union, The application of a computational screening methodology based on the calculation of intermolecular interaction energies has guided the discovery of new multicomponent solid forms of the oral antiviral Adefovir Dipivoxyl. Three new cocrystals with resorcinol, orcinol and hydroquinone have been synthesized and thoroughly characterized. They show improved dissolution profiles with respect to the single solid form, particularly the cocrystals of orcinol and resorcinol, which have 3.2- and 2-fold faster dissolution rates at stomach conditions (pH 1.5). Moreover, dynamic dissolution experiments that simultaneously mimic both the pH variation along the gastrointestinal tract and the partition into biological membranes show that, in addition to the faster initial dissolution, Adefovir Dipivoxyl also penetrates faster into the organic membranes in the form of resorcinol and orcinol cocrystals.

Published
2022
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