Rigaku Discovers New Polymorph (κ-form) of Indomethacin

Rigaku Corporation, a group company of Rigaku Holdings and a global solution partner for X-ray analytical instruments, is pleased to announce that research results, jointly conducted with Shionogi & Co., Ltd., JEOL Ltd., and Meiji Pharmaceutical University, have been published in the world-renowned academic journal "Crystal Growth & Design" in the field of crystallography.

▲Cover of "Crystal Growth & Design" June 2026 issue (featuring this research)

This research involved the discovery of a new crystalline polymorph (κ-form) of "indomethacin," a widely used analgesic and anti-inflammatory drug, followed by its structural analysis and characterization. Although indomethacin has been studied for many years, the discovery of a new crystalline polymorph is extremely rare, and this achievement holds significant importance for both crystallography and pharmaceutical research.

Crystalline polymorphism refers to a state where a substance with the same chemical composition exhibits different properties, such as solubility and stability, due to differences in crystal structure. Variations in crystalline polymorphs affect drug quality and ease of manufacturing, making it a crucial research topic in pharmaceutical development. The newly discovered crystalline polymorph is expected to deepen the understanding of such pharmaceutical research.

In this study, structural analysis was performed using the MicroED method with the "XtaLAB Synergy-ED," an integrated electron diffraction platform jointly developed by Rigaku and JEOL. The newly discovered polymorph had extremely small crystal sizes, less than 1 micrometer, making structural analysis difficult with conventional X-ray diffraction. However, structural analysis was successfully achieved using this instrument.

Furthermore, by examining the arrangement of molecules within the crystals, the intermolecular interactions contributing to the stabilization of this polymorph were elucidated. This achievement demonstrates the effectiveness of MicroED in exploring new crystalline polymorphs and is expected to be applied to improve drug quality and development efficiency.

【Paper Title】

“Discovery of a New Polymorph, κ-form of Indomethacin”

【Journal】

Crystal Growth & Design

【DOI】

https://doi.org/10.1021/acs.cgd.5c01534

【Collaborating Institutions】

Shionogi & Co., Ltd.

https://www.shionogi.com/jp/ja/

JEOL Ltd.

https://www.jeol.co.jp/

Meiji Pharmaceutical University

https://www.my-pharm.ac.jp/

【About Rigaku Group】

The Rigaku Group is a group of engineers driving society forward with advanced analytical technologies, including X-ray analysis as its core and thermal analysis. Since its founding in 1951, as a solution partner for industrial and research analysis, it has been growing together with customers in 136 countries and regions. It boasts an extremely high share in Japan, with overseas sales accounting for about 70%. The application fields are expanding daily, from semiconductors, electronic materials, batteries, and environment/energy to life sciences. Over 2,000 employees worldwide are working to realize innovation with the mission "Changing the world with the power of sight." For more information, please visit rigaku-holdings.com.