The polymorphism of sulphathiazole

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

“…In the XRPD pattern of sulfathiazole form III, significant intensity variations are observed between the calculated and experimental patterns due to preferred crystal orientation effects. 35 Therefore, the 2θ regions used for the analysis must be carefully selected. 2θ peaks in the 21.0-23.0 range are most affected by preferred crystal orientation and this region is not analytically useful.…”

“…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.…”

“…35,45 Recently, the preparation of amorphous sulfathiazole by cryo-milling has been reported but no stability testing of the amorphous phase was described. 13 In this paper we describe a detailed study of the effect of cryo-milling on two sulfathiazole polymorphic forms I and III.…”

A combined approach of differential scanning calorimetry and hot-stage microscopy with image analysis in the investigation of sulfathiazole polymorphism

“…According to a report [29], a single melting peak of form II at its melting temperature can only be obtained if the crystals were purely form II. If only the slightest amount of form I present, form I will crystallise during the melting process of form II [29]. This indicates that the crystals obtained are actually a mixture of form I, form II and form III.…”

“…At present, it has five known polymorphs that are well characterised and clearly described in the literature [24][25][26]. Although the polymorphism of sulfathiazole has been extensively and repeatedly investigated by various researchers [27][28][29][30], it remains difficult to produce a pure polymorph; most of the time, the desired polymorph contains impurities from at least one other form [31][32][33][34].…”