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Characterization of crystalline and amorphous forms of irbesartan by multi-nuclear solid-state NMR

Skotnicki, Marcin; Hodgkinson, Paul

Characterization of crystalline and amorphous forms of irbesartan by multi-nuclear solid-state NMR Thumbnail


Authors

Marcin Skotnicki



Abstract

Irbesartan (IRB) is an antihypertensive drug which exhibits the rare phenomenon of desmotropy; its 1H- and 2H- tetrazole tautomers can be isolated as distinct crystalline forms. The crystalline forms of IRB are poorly soluble, hence the amorphous form is potentially of interest for its faster dissolution rate. The tautomeric form and the nature of hydrogen bonding in amorphous IRB are unknown. In this study, crystalline form A and amorphous form of irbesartan were studied using 13C, 15N and 1H solid-state NMR. Variable-temperature 13C SSMNR studies showed alkyl chain disorder in the crystalline form of IRB, which may explain the conflicting literature crystal structures of form A (the marketed form). 15N NMR indicates that the amorphous material contains an approximately 2:1 ratio of 1H- and 2H-tetrazole tautomers. Static 1H SSNMR and relaxation time measurements confirmed different molecular mobilities of the samples and provided molecular-level insight into the nature of the glass transition. SSNMR is shown to be a powerful technique to investigate the solid state of disordered active pharmaceutical ingredients.

Citation

Skotnicki, M., & Hodgkinson, P. (2022). Characterization of crystalline and amorphous forms of irbesartan by multi-nuclear solid-state NMR. Solid State Nuclear Magnetic Resonance, 118, https://doi.org/10.1016/j.ssnmr.2022.101783

Journal Article Type Article
Acceptance Date Feb 14, 2022
Online Publication Date Mar 2, 2022
Publication Date 2022-04
Deposit Date Apr 7, 2022
Publicly Available Date Sep 3, 2023
Journal Solid State Nuclear Magnetic Resonance
Print ISSN 0926-2040
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 118
DOI https://doi.org/10.1016/j.ssnmr.2022.101783
Public URL https://durham-repository.worktribe.com/output/1209084

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