Quantitative nuclear magnetic resonance analysis of solid formoterol fumarate and its dihydrate

Apperley, David C.; Harris, Robin K.; Larsson, Tomas; Malmström, Torsten

doi:10.1002/jps.10500

Cited by 26 publications

(16 citation statements)

References 21 publications

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“…12). From solid state NMR investigations it is known that this disorder is dynamic and also that cooling to 223 K does not stop the movement 17. Only a limited improvement was achieved by collecting X‐ray data at 200 K.…”

Section: Resultsmentioning

confidence: 99%

Thermodynamic Stability and Crystal Structures for Polymorphs and Solvates of Formoterol Fumarate

Jarring

Larsson

Stensland

et al. 2006

Journal of Pharmaceutical Sciences

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Section: Resultsmentioning

confidence: 99%

Thermodynamic Stability and Crystal Structures for Polymorphs and Solvates of Formoterol Fumarate

Jarring

Larsson

Stensland

et al. 2006

Journal of Pharmaceutical Sciences

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“…In a similar fashion, the polymorphic content of a drug formulation can be monitored, as shown (Apperley et al 2003) in Figure 10, from which a molar concentration ratio of 43%:57% can be obtained for formoterol fumarate (IX) in admixture with its dihydrate when the total drug concentration was 2% in lactose.…”

Section: Quantitationmentioning

confidence: 99%

Applications of solid-state NMR to pharmaceutical polymorphism and related matters

Harris

2007

Journal of Pharmacy and Pharmacology

166

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Magic-angle spinning NMR is now making a significant contribution to our understanding of the structure of polymorphs and solvates of pharmaceutical significance. This personal review article discusses a range of applications, with particular emphasis on information about crystallography, for which NMR can address problems that cannot be readily solved by diffraction techniques (such as dynamic disorder and non-stoichiometric hydration). Unlike diffractograms, NMR spectra yield immediate chemical information. Moreover, heterogeneous samples can be investigated and amorphous content provides no significant barrier to studies. Furthermore, NMR can be an effective technique for quantitation (down to the level of ca. 1%). Additional strength is being derived from computation of chemical shifts in solids, using a code that takes account of the spatial repetition inherent in crystalline materials.

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“…Figure 1(a) gives its chemical structure and shows the labelling used herein for the carbon nuclei. The forms of formoterol fumarate have been investigated by a variety of techniques [4,5]. Of particular interest here are the isomorphous diformoterol fumarate disolvates, where the solvent is ethanol or isopropanol, and formoterol fumarate form C which is obtained by desolvation of these solvates.…”

Section: Introductionmentioning

confidence: 99%

NMR characterisation of dynamics in solvates and desolvates of formoterol fumarate

Apperley

Markwell

Frantsuzov

et al. 2013

Phys. Chem. Chem. Phys.

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Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACT Solid-state NMR is used to characterise dynamics in the ethanol solvate of the pharmaceutical material formoterol fumarate and its associated desolvate. Jump rates and activation barriers for dynamic processes such as phenyl ring rotation and methyl group rotational diffusion are derived from 1D-EXSY and 13 C spin-lattice relaxation times respectively. 2 H and 13 C spin-lattice relaxation times measured under magic-angle spinning conditions are used to show that the fumarate ion in the desolvate is undergoing smallamplitude motion on a frequency scale of 100s of MHz at ambient temperature with an activation parameter of about 32 kJ mol -1 . Exact calculations of relaxation times under MAS provide a simple and robust means to test motional models in cases where relaxation rate maxima are observed, including for systems where the crystal structure of the material is unknown.

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Quantitative nuclear magnetic resonance analysis of solid formoterol fumarate and its dihydrate

Cited by 26 publications

References 21 publications

Thermodynamic Stability and Crystal Structures for Polymorphs and Solvates of Formoterol Fumarate

Thermodynamic Stability and Crystal Structures for Polymorphs and Solvates of Formoterol Fumarate

Applications of solid-state NMR to pharmaceutical polymorphism and related matters

NMR characterisation of dynamics in solvates and desolvates of formoterol fumarate

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