Crystal structure, solid-state NMR spectra, and oxygen reactivity of five crystal forms of prednisolone tert-butylacetate

Byrn, Stephen R.; Sutton, Paul; Tobias, Brian; Frye, J.; Main, P. C.

doi:10.1021/ja00213a039

Cited by 79 publications

(41 citation statements)

References 5 publications

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“…It is often clear that solid state degradation of pharmaceuticals is often related to molecular mobility [47][48][49] .…”

Section: Phase Transformation During Processingmentioning

confidence: 99%

Untitled

2011

IJPSR

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Many drugs exist in crystalline solid form due to reasons of stability and ease of handling during the various stages of drug development. Crystalline solids can exist in the form of polymorphs, solvates or hydrates. Phase transitions such as polymorph inter-conversion, formation of hydrates, desolvation of solvates, and conversion of the crystalline to amorphous form may occur during various pharmaceutical processes. This could change the dissolution rate and transport characteristics of the drug. The current focus of research in the area is to understand the origins of polymorphism at the molecular level, and to predict and prepare the most stable polymorph of the drug. The aim of this review is to understand the recent development in the area of solid state crystallinity, amorphous state and to address the current challenges faced by pharmaceutical formulation, process development scientists and to anticipate future developments.

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“…It is often clear that solid state degradation of pharmaceuticals is often related to molecular mobility [47][48][49] .…”

Section: Phase Transformation During Processingmentioning

confidence: 99%

Untitled

2011

IJPSR

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show abstract

“…Different crystal forms can have relatively large changes in the chemical shift of some resonances. There are many examples of different crystalline forms giving unique NMR spectra [8,[22][23][24][25]. Padden et al have compared solid-state NMR spectroscopy with powder X-ray diffraction (PXRD) in an investigation of neotame polymorphs.…”

Section: Identificationmentioning

confidence: 99%

“…Following the conversion of a mixture of anhydrous forms over time, they found that PXRD could not detect a change in the patterns during the conversion process, whereas up to seven forms were detected in 13 C NMR spectra [25]. Byrn and coworkers have published several papers investigating polymorphism in drug compounds [22,23,26]. In a 13 C study of benoxaprofen, nabilone, and cefazolin, they found that CPMAS NMR spectra of the different crystal forms of the drugs were indeed different [22].…”

Section: Identificationmentioning

confidence: 99%

“…They also performed preliminary studies on pharmaceutical granulations of these drugs and found that the spectrum of the API could be discerned in the formulation. Five different crystal forms of prednisolone tert-butylacetate were investigated in another study, and again each solid form had a unique 13 C NMR spectrum [23]. Four of the forms were solvates, while one was anhydrous.…”

Section: Identificationmentioning

confidence: 99%

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Solid‐state NMR Spectroscopy

Lubach

Munson

2006

Polymorphism

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“…As a result, scientists often rely on the oxidative or other chemical stability of drug candidates in solution to speculate on their behavior in solid state, hoping that the molecules will behave consistently or similarly in these two distinct physical states. However, given the substantial difference in molecular environments between the solid and solution states, the complexity associated with solidstate forms such as polymorphism, hydrates, salts, and the potential of a chemical reaction modulated by topochemistry, 8,9 such a simple extrapolation may prove inadequate and even misleading at times. For a given drug candidate intended to be formulated as a solid dosage form, besides its physicochemical properties such as melting point, solubility, dissolution rate, hygroscopicity, and thermal stability (e.g.…”

Section: Introductionmentioning

confidence: 99%