Structural characterization of cevimeline and its trans-impurity by single crystal XRD

• Single crystal X-ray analysis of cevimeline is reported for the first time.
• Single crystal X-ray analysis of trans-cevimeline is reported for the first time.
• PXRD, thermal analysis and solubility studies of both compounds is provided.

Cevimeline is muscarinic receptor agonist which increases secretion of exocrine glands. Cevimeline base is a liquid (m.p. 20–25 °C) at ambient conditions, therefore its pharmaceutical formulation as a solid hydrochloride hemihydrate has been developed. The synthesis of cevimeline yields its cis- and trans-isomers and only the cis-isomer is recognized as the API and used in the finished formulation. In this study structural and physicochemical investigations of hydrochloride hemihydrates of cis- and trans-cevimelines have been performed. Single crystal X-ray analyses of both cis- and trans-isomers of cevimeline are reported here for the first time. It was found that the cis-isomer, the API, has less dense crystal packing, lower melting point and higher solubility in comparison to the trans-isomer.

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