Thermal and Microscopic Investigation of the Unusual Phase Behaviors of Ephedrine Cyclamate

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Thermal and Microscopic Investigation of the Unusual Phase Behaviors of Ephedrine Cyclamate

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2023-05

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Ephedrine is a popular drug used as a bronchodilator and a CNS stimulant. However, it has an extremely bitter taste and very low tabletability. Therefore, a new 1:1 cyclamate salt was formed. The single crystal structure of the new salt was determined using X-ray diffraction, which was called form I. Mechanical analysis revealed that form I is significantly more plastic and exhibits better tabletability than its parent compounds, ephedrine hydrochloride and sodium cyclamate. Thermal analysis proved the existence of another polymorph, form II, which is formed upon heating form I to about 165° C. The two polymorphs are enantiotropically related. DSC revealed that the conversion of form II to I cooling depended on pressure, where it occurred only on cooling a sample heated in a hermetically sealed pan and not in a pan with a pinhole. Attempts were made to produce Form II and understand polymorphism better. However, the phenomenon was preceded by the melting of Form I. Therefore, clear segregation is required between the two processes to understand polymorphism in Eph-Cyc better. The effects of heating rate and crystal size were studied for better optimization. TGA was used as a final attempt to produce Form II using thermal techniques.

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University of Minnesota M.S. thesis. May 2023. Major: Pharmaceutics. Advisor: Changquan Calvin Sun. 1 computer file (PDF); xi, 55 pages.

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Agarwal, Arushi. (2023). Thermal and Microscopic Investigation of the Unusual Phase Behaviors of Ephedrine Cyclamate. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/258561.

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