Thermodynamics of Polymorphs and Solvates

Coquerel, Gérard

doi:10.1002/9783527697847.ch4

Cited by 6 publications

(3 citation statements)

References 65 publications

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“…Polymorphism studies also are of paramount importance in the pharmaceutical industry since different polymorphs of the same API, with distinct crystal structures, can yield to completely different physicochemical properties [7,8]. At first, cocrystals were thought to be a solution to polymorphism problems presented by APIs.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…Control over the solid-state form of active pharmaceutical ingredients (APIs) ensures desired material properties, including processability and solubility, and hence requires in-depth understanding of API stability and possible solid state transitions, governed by both thermodynamic and kinetic factors. , Accordingly, significant research efforts have been dedicated to diminish this knowledge gap that continuously aids in the development of better formulations with capabilities to offset poor solubility and/or permeability . This issue is particularly prevalent in oral medicines that require API particulates to overcome the solubility barrier in order to be absorbed.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Gastrointestinal Biomolecules on Solid-State Transformations in Pharmaceutical Particulates

et al. 2023

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Adsorption of gut relevant biomolecules onto particles after oral administration of solid oral dosage forms is expected to form a "gastrointestinal corona", which could influence solution-mediated solid-state transformations on exposure of drug particles to gastrointestinal fluids. Low-frequency Raman (LFR) spectroscopy was used in this study to investigate in situ solid-state phase transformations under biorelevant temperature and pH conditions along with the presence of biomolecules. Meltquenched amorphous indomethacin was used as a model solid particulate, and its solid-state behavior was evaluated at 37 °C and pH 1.2−6.8 with or without the presence of typical bile salt/phospholipid mixtures emulating fed-state conditions. Overall, a change in the solid-state transformation pathway from amorphous to crystalline drug was observed, where an intermediate ε-form that initially formed at pH 6.8 was suppressed by the addition of endogenous gastrointestinal biomolecules. These solid-state changes were corroborated using time-resolved synchrotron small-and wide-angle X-ray scattering (SAXS/WAXS). Additionally, the bile salt and phospholipid mixture partly prevented the otherwise strong aggregation between drug particles at more acidic conditions (pH ≤ 4.5) and helped to shift the balance against the intrinsic hydrophobicity of indomethacin as well as the plasticization effect brought about by the physiological temperature (i.e., the stickiness arising from the supercooled liquid state at 37 °C). The overall results highlight the importance of evaluating the impact that endogenous biomolecules may have on the solid-state characteristics of drug molecules in dissolution media, where analytical tools such as LFR spectroscopy can serve as an attractive avenue for accessing timeresolved solid-state information on time-scales that are difficult to achieve with other techniques such as X-ray diffraction.

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“…Polymorphic phases of a material give an excellent opportunity to study the inter-relations of physical properties with different arrangements of the same set of atoms. − The interatomic distances between the atoms, that is, the types of atomic bonds or the types of orbital overlapping, play a key role in controlling the physical parameters. A material, subjected to a particular environment or condition, prefers to form in a crystal structure having minimum formation energy.…”

Section: Introductionmentioning

confidence: 99%

Similar and Dissimilar Properties of Polymorphic Phases of NdIr₃

et al. 2022

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We report the formation and physical properties of a new polymorphic phase of NdIr3 (AuBe5-type cubic), along with those of one earlier reported phase (AuCu3-type cubic), formed together during the synthesis process. Our experimental data shows that the magnetic properties of these two phases are of contrasting characters: the former becomes ferromagnetic at low temperatures, while the latter remains paramagnetic down to the lowest measured temperature, 2.5 K. Interestingly, the magnetic properties of the cubic AuBe5-type phase have an uncanny similarity to that recently reported in another polymorphic phase (rhombohedral PuNi3-type) of the same compound. We have investigated the origin of such similarities and dissimilarities in magnetic properties of these three polymorphic phases of NdIr3 through a few diverse directions: structural, theoretically calculated spin-polarized density of states, and magnetic ground state and RKKY framework. We have shown that the similarity of the Curie temperature of the cubic AuBe5-type and rhombohedral PuNi3-type phases is the result of aperiodicity in the first nearest neighbors and similarity in the Fermi momentum space.

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Thermodynamics of Polymorphs and Solvates

Cited by 6 publications

References 65 publications

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

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

The Influence of Gastrointestinal Biomolecules on Solid-State Transformations in Pharmaceutical Particulates

Similar and Dissimilar Properties of Polymorphic Phases of NdIr₃

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Thermodynamics of Polymorphs and Solvates

Cited by 6 publications

References 65 publications

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

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

The Influence of Gastrointestinal Biomolecules on Solid-State Transformations in Pharmaceutical Particulates

Similar and Dissimilar Properties of Polymorphic Phases of NdIr3

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Product

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Similar and Dissimilar Properties of Polymorphic Phases of NdIr₃