Characterization of Temperature-Induced Phase Transitions in Five Polymorphic Forms of Sulfathiazole by Terahertz Pulsed Spectroscopy and Differential Scanning Calorimetry

Zeitler, J. Axel; Newnham, David; Taday, Philip F.; Threlfall, Terry L.; Lancaster, Robert W.; Berg, Rolf W.; Strachan, Clare J.; Pepper, M.; Gordon, Keith C.; Rades, Thomas

doi:10.1002/jps.20719

Cited by 134 publications

(118 citation statements)

References 26 publications

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“…The first endotherm was attributed to a solid-state phase transition of form III into form I. The event with the higher temperature onset was consistent with the melting of ST form I (19). Thermal analysis confirmed PXRD results that ST before being processed was form III.…”

Section: Thermal Analysissupporting

confidence: 61%

Modification of the Solid-State Nature of Sulfathiazole and Sulfathiazole Sodium by Spray Drying

et al. 2012

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Abstract. Solid-state characterisation of a drug following pharmaceutical processing and upon storage is fundamental to successful dosage form development. The aim of the study was to investigate the effects of using different solvents, feed concentrations and spray drier configuration on the solid-state nature of the highly polymorphic model drug, sulfathiazole (ST) and its sodium salt (STNa). The drugs were spray-dried from ethanol, acetone and mixtures of these organic solvents with water. Additionally, STNa was spraydried from pure water. The physicochemical properties including the physical stability of the spray-dried powders were compared to the unprocessed materials. Spray drying of ST from either acetonic or ethanolic solutions with the spray drier operating in a closed cycle mode yielded crystalline powders. In contrast, the powders obtained from ethanolic solutions with the spray drier operating in an open cycle mode were amorphous. Amorphous ST crystallised to pure form I at ≤35 % relative humidity (RH) or to polymorphic mixtures at higher RH values. The usual crystal habit of form I is needle-like, but spherical particles of this polymorph were generated by spray drying. STNa solutions resulted in an amorphous material upon processing, regardless of the solvent and the spray drier configuration employed. Moisture induced crystallisation of amorphous STNa to a sesquihydrate, whilst crystallisation upon heating gave rise to a new anhydrous polymorph. This study indicated that control of processing and storage parameters can be exploited to produce drugs with a specific/desired solid-state nature.

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Section: Thermal Analysissupporting

confidence: 61%

Modification of the Solid-State Nature of Sulfathiazole and Sulfathiazole Sodium by Spray Drying

et al. 2012

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“…[19,24]. The NIR spectra of the five polymorphs and amorphous of FII and FIV [13,25]. As will be seen below this problem is somewhat reduced in this work as mixtures containing FIII are not observed in most cases.…”

Section: Nir Spectramentioning

confidence: 80%

Solid-State Transformations of Sulfathiazole Polymorphs: The Effects of Milling and Humidity

Erxleben

Hodnett

et al. 2013

Crystal Growth & Design

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The effect of milling on the solid-state transitions of sulfathiazole polymorphs in the absence and presence of solvent and excipients was monitored by X-ray powder diffraction (XRPD), attenuated total reflectance infrared (ATR-IR) and near-infrared (NIR) spectroscopy. Sulfathiazole forms FII-FV undergo a transformation toward the metastable FI, which involves an intermediate amorphous stage upon milling at ambient temperature. Milling FIII with catalytic amounts of solvent converts FIII to FIV or to mixtures of FI and FIV depending on the solvent used. Pure FIV can be easily prepared from FIII by this method. The physical stability of pure sulfathiazole forms in the presence of different levels of relative humidity (RH) was also investigated. At low RH all sulfathiazole forms are stable but at RH levels above 70% FII, FIII and FIV remain stable while FI and FV transform to mixtures of FII and FIV without any apparent change in the external form of the crystals. Co-milling FIII with a range of excipients gave results which depended on the excipient used and co-milling with cellulose gave samples which had an amorphous content that was stable at 10% RH for at least nine months at ambient temperature.

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“…34 The physicochemical properties of the five forms have been described in detail. [35][36][37][38][39][40] Relative thermodynamic stabilities at 0 K are generally accepted to follow the order of the densities of the structures, i.e. III ≈ IV > II > I > V, with form I being metastable at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Formation, Physical Stability, and Quantification of Process-Induced Disorder in Cryomilled Samples of a Model Polymorphic Drug

MacFhionnghaile

Caron

et al. 2013

Journal of Pharmaceutical Sciences

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Characterization of Temperature-Induced Phase Transitions in Five Polymorphic Forms of Sulfathiazole by Terahertz Pulsed Spectroscopy and Differential Scanning Calorimetry

Cited by 134 publications

References 26 publications

Modification of the Solid-State Nature of Sulfathiazole and Sulfathiazole Sodium by Spray Drying

Modification of the Solid-State Nature of Sulfathiazole and Sulfathiazole Sodium by Spray Drying

Solid-State Transformations of Sulfathiazole Polymorphs: The Effects of Milling and Humidity

Formation, Physical Stability, and Quantification of Process-Induced Disorder in Cryomilled Samples of a Model Polymorphic Drug

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