Effects of Moisture and Residual Solvent on the Phase Stability of Orthorhombic Paracetamol

Kachrimanis, Kyriakos; Fucke, Katharina; Noisternig, Michael F.; Siebenhaar, Bernd; Griesser, Ulrich J.

doi:10.1007/s11095-007-9529-4

Cited by 38 publications

(41 citation statements)

References 35 publications

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“…The behaviour and appearance of metacetamol form II is rather similar to that of the "elusive" paracetamol form III: both substances form drops with a large number of small crystallites radiating from the centre to borders of the drop. 8,37 Conclusions A new polymorph (form II) of metacetamol has been identified and characterised using a range of techniques. This was demonstrated in an experiment in which a sample of form II was divided equally into three portions which were stored under different levels of relative humidity.…”

Section: Transitions Between Metacetamol Forms I and Iimentioning

confidence: 99%

A new polymorph of metacetamol

et al. 2015

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Metacetamol is a structural isomer of the widely used drug paracetamol and is being considered as a promising alternative to the latter because of its lower toxicity. Due to the importance of the well-known polymorphism of paracetamol, an investigation of the polymorphism of metacetamol was successfully undertaken. A new polymorph of metacetamol has been discovered and extensively characterised using a variety of analytical techniques (IR-and Raman spectroscopy, UV-visible optical spectroscopy, X-ray powder and single-crystal diffraction, TGA and DSC). A procedure for the reliable and reproducible preparation of the new polymorph is described. Its properties and crystal structure are compared with those of the previously known polymorph, as well as with those of paracetamol. CrystEngComm This journal isScheme 1 Molecular structures of metacetamol (left) and paracetamol (right) containing the same characteristic functional groups.

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Section: Transitions Between Metacetamol Forms I and Iimentioning

confidence: 99%

A new polymorph of metacetamol

et al. 2015

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“…Another example is the thermal dehydration of nedocromil magnesium pentahydrate ( Figure 9) [64], which shows the slight differences in dehydration behaviour if heated in an open system, where the water can readily leave the direct environment of the sample, and a closed system, in which the surrounding sample's atmosphere is saturated with water and the dehydration thus hindered. Paracetamol shows a humidity triggered phase transition of its solution grown form II to the stable form I (Figure 10) [65]. Form II is the thermodynamically metastable polymorph at room temperature but is of interest to the pharmaceutical industry to process, since this crystal form can be directly compacted into tablets, whereas form I has to be granulated with excipients in a separate step before compaction.…”

Section: Powder X-ray Diffractionmentioning

confidence: 99%

X-ray and Neutron Diffraction in the Study of Organic Crystalline Hydrates

Fucke

Steed

2010

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A review. Diffraction methods are a powerful tool to investigate the crystal structure of organic compounds in general and their hydrates in particular. The laboratory standard technique of single crystal X-ray diffraction gives information about the molecular conformation, packing and hydrogen bonding in the crystal structure, while powder X-ray diffraction on bulk material can trace hydration/dehydration processes and phase transitions under non-ambient conditions. Neutron diffraction is a valuable complementary technique to X-ray diffraction and gives highly accurate hydrogen atom positions due to the interaction of the radiation with the atomic nuclei.Although not yet often applied to organic hydrates, neutron single crystal and neutron powder diffraction give precise structural data on hydrogen bonding networks which will help explain why hydrates form in the first place.

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“…Qi et al for instance (Qi et al, 2008) suggest that the re-crystallized form of paracetamol may be dependent on the nature of the head-space gas. The presence of oxygen or other component in the air or trace of moisture at the head-space of the initial paracetamol sample resulting in a greater preponderance for the formation of meta-stable polymorphs (Kachrimanis et al, 2008).…”

Section: Introductionmentioning

confidence: 99%