New Polymorph of Indomethacin Discovered

- Joint Research Involving Rigaku Published in Crystal Growth & Design -

Rigaku Corporation, a global solution partner in X-ray analytical systems and a group company of Rigaku Holdings Corporation (headquarters: Akishima, Tokyo; CEO: Jun Kawakami; “Rigaku”), announced that the results of a joint research project conducted with Shionogi & Co., Ltd., JEOL Ltd., and Meiji Pharmaceutical University have been published in Crystal Growth & Design, a world-renowned international journal in the field of crystallography.

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Cover of the June 2026 issue of Crystal Growth & Design, featuring this research.

This research uncovered a previously unknown polymorph (κ-form) of indomethacin, a widely used pain relief and anti-inflammatory drug. The research team also conducted structural analysis and characterization of the newly identified crystal form. Although indomethacin has been the subject of pharmaceutical research for years, the discovery of a new polymorph is an extremely rare event, making this discovery highly significant for both crystallography and pharmaceutical research.

Crystal polymorphs are different crystal structures formed from the same chemical compound, resulting in variations in properties such as solubility and stability. Differences among polymorphs are an important research theme in pharmaceutical development, as they affect drug quality and manufacturability. The newly discovered polymorph is expected to deepen understanding in future pharmaceutical research.

Structural analysis in this research project was carried out using the MicroED method with XtaLAB Synergy-ED, a fully integrated electron diffractometer jointly developed by Rigaku and JEOL Ltd. The newly discovered polymorph consisted of extremely small crystals measuring less than one micrometer, making structural analysis difficult using conventional X-ray diffraction methods. By leveraging MicroED technology, the research team successfully determined the crystal structure of the new κ-form.

Furthermore, analysis of molecular arrangements within the crystal revealed intermolecular interactions contributing to the stability of the polymorph. These findings demonstrate the effectiveness of MicroED for discovering previously undetectable polymorphs and highlight its potential to improve pharmaceutical quality and accelerate drug development.

Paper Title: Discovery of a New Polymorph, κ-form of Indomethacin
Journal: Crystal Growth & Design
DOI: https://doi.org/10.1021/acs.cgd.5c01534

Research Partners
Shionogi & Co., Ltd.
https://www.shionogi.com/global/en/

JEOL Ltd.
https://www.jeol.com/

Meiji Pharmaceutical University
https://www.my-pharm.ac.jp/en/

About the Rigaku Group
Since its establishment in 1951, the engineering professionals of the Rigaku group have been dedicated to benefiting society with leading-edge technologies, notably including its core fields of X-ray and thermal analysis. With a market presence in 136 countries and regions and some 2,000 employees from 9 global operations, Rigaku is a solution partner in industry and research analysis institutes. Our overseas sales ratio has reached approximately 70% while sustaining an exceptionally high market share in Japan. Together with our customers, we continue to develop and grow. As applications expand from semiconductors, electronic materials, batteries, environment, resources, energy, life science to other high-tech fields, Rigaku realizes innovations “To Improve Our World by Powering New Perspectives.”
For details, please visit: rigaku-holdings.com/english

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