The use of dynamic vapour sorption and near infra-red spectroscopy (DVS-NIR) to study the crystal transitions of theophylline and the report of a new solid-state transition

Vora, Ketan L; Buckton, Graham; Clapham, David

doi:10.1016/j.ejps.2004.01.009

Cited by 38 publications

(24 citation statements)

References 21 publications

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“…44,45,49 The results obtained in the present work differ significantly from all the previously reported values. These discrepancies can have several explanations.…”

Section: Hydration Process Of Tpacontrasting

confidence: 88%

“…This is probably the reason why the reported kinetic results of the literature (values of rate constants and choice of the kinetic model) are so different from each other. 44,45,49 However, it is possible to evaluate the kinetic parameters for the second step, using the points shown in Figure 7 after the plateau. The results for this second step can be identically described by either the AvramiErofeev models or by the simple a zero-order diffusion mechanism (r 2 values and s b values within 0.98-0.99 and 0.00030-0.00060 intervals, respectively).…”

Section: Dehydration Process Of Tphmentioning

confidence: 99%

“…TPh and TPh ! TPa transformations, and both processes have been studied for the bulk powder 38,[44][45][46][47][48][49][50][51][52][53][54][55][56] and for tablets. [57][58][59][60] The effects of different excipients on these hydration and dehydration processes have also been evaluated by different authors.…”

Section: Introductionmentioning

confidence: 99%

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Probing Pseudopolymorphic Transitions in Pharmaceutical Solids using Raman Spectroscopy: Hydration and Dehydration of Theophylline

Amado

Nolasco

Ribeiro‐Claro

2007

Journal of Pharmaceutical Sciences

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Theophylline is known to undergo vapor phase induced hydrate-anhydrate pseudopolymorphic transformations, which can affect its bioavailability. In this work, the kinetics of the pseudopolymorphic transitions of theophylline crystals in different storage conditions is studied using a vibrational spectroscopic technique. While the hydration is a single-step process with a half-life time of ca. 5 h, the dehydration occurs through a two-step mechanism. In addition, the phase stability of hydrate-anhydrate systems in different relative humidity (RH) conditions was probed. The critical RH for anhydrous teophylline was found to be at ca. 79%, while the critical RH for dehydration is ca. 30%. ß

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“…44,45,49 The results obtained in the present work differ significantly from all the previously reported values. These discrepancies can have several explanations.…”

Section: Hydration Process Of Tpacontrasting

confidence: 88%

Section: Dehydration Process Of Tphmentioning

confidence: 99%

See 1 more Smart Citation

Probing Pseudopolymorphic Transitions in Pharmaceutical Solids using Raman Spectroscopy: Hydration and Dehydration of Theophylline

Amado

Nolasco

Ribeiro‐Claro

2007

Journal of Pharmaceutical Sciences

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“…In-situ Raman spectroscopy Theophylline [123] Hydrate formation to theophylline monohydrate, dehydration Dynamic vapour sorption apparatus NIR spectroscopy Theophylline [124] Solution-mediated hydrate formation to theophylline monohydrate, dehydration…”

Section: Solvatesmentioning

confidence: 99%

Analysis of solid-state transformations of pharmaceutical compounds using vibrational spectroscopy

et al. 2009

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Objectives Solid-state transformations may occur during any stage of pharmaceutical processing and upon storage of a solid dosage form. Early detection and quantification of these transformations during the manufacture of solid dosage forms is important since the physical form of an active pharmaceutical ingredient can significantly influence its processing behaviour, including powder flow and compressibility, and biopharmaceutical properties such as solubility, dissolution rate and bioavailability. Key findings Vibrational spectroscopic techniques such as infrared, near-infrared, Raman and, most recently, terahertz pulsed spectroscopy have become popular for solidstate analysis since they are fast and non-destructive and allow solid-state changes to be probed at the molecular level. In particular, Raman and near-infrared spectroscopy, which require no sample preparation, are now commonly used coupled to fibreoptic probes and are able to characterise solid-state conversions in-line. Traditionally, uni-or bivariate approaches have been used to analyse spectroscopic data sets; however, recently the simultaneous detection of several solid-state forms has been increasingly performed using multivariate approaches where even overlapping spectral bands can be analysed. Summary This review discusses the applications of different vibrational spectroscopic techniques to detect and monitor solid-state transformations possible for crystalline polymorphs, hydrates and amorphous forms of pharmaceutical compounds. In this context, the theoretical basis of solid-state transformations and vibrational spectroscopy and common experimental approaches are described, including recent methods of data analysis.

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“…Many experimental techniques permit to characterize these influences [9]. Among them, the association of techniques controlling the Relative Humidity (hereafter RH), like the Dynamic Vapour Sorption (hereafter DVS), with the static vapour sorption [10], the Infrared Spectroscopy [11] [12] [13] or classical analyses as X-Ray Powder Diffraction (XRPD hereafter), Thermogravimetric analyses associated to Differential Scanning Calorimetry (TG-DSC hereafter) [13], [14] are very helpful to understand solid-vapour equilibria. The present study aims at describing these equilibria through some examples treated in our laboratory.…”

Section: Introductionmentioning

confidence: 99%

Influence of solid/vapour equilibria on the stability of organic solids

Couvrat

Cartigny

2009

XXXV JEEP – 35th Conference on Phase Equilibria

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The influence of water (in its gaseous state) on the stability of crystallized organic compounds was investigated. Through two examples of solid/vapour equilibria, several behaviours were highlighted (stoichiometric or non stoichiometric hydrates, hydration/dehydration mechanisms, stability domains of multi-hydrates as a function of relative humidity). Phase diagrams (as a function of partial water pressure) and stability diagrams have been proposed for each example. This study illustrates that solid/vapour equilibrium knowledge is a crucial step during the complete characterization of solid organic compounds.

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The use of dynamic vapour sorption and near infra-red spectroscopy (DVS-NIR) to study the crystal transitions of theophylline and the report of a new solid-state transition

Cited by 38 publications

References 21 publications

Probing Pseudopolymorphic Transitions in Pharmaceutical Solids using Raman Spectroscopy: Hydration and Dehydration of Theophylline

Probing Pseudopolymorphic Transitions in Pharmaceutical Solids using Raman Spectroscopy: Hydration and Dehydration of Theophylline

Analysis of solid-state transformations of pharmaceutical compounds using vibrational spectroscopy

Influence of solid/vapour equilibria on the stability of organic solids

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