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[NMR studies on cetirizine hydrochloride]
Qian Li1, Wen-bin Shen, Qiao-gen Zou
1Center for Instrumental Analysis, China Pharmaceutical University, Nanjing 210009, China.
Yao Xue Xue Bao = Acta Pharmaceutica Sinica
|January 21, 2004
Summary
Cetirizine hydrochloride exhibits multiple conformations in DMSO-d6 solution at room temperature, observable via NMR. Temperature increase or D2O addition facilitates conformational exchange or stabilizes a specific form.
Area of Science:
- Nuclear Magnetic Resonance (NMR) spectroscopy
- Organic Chemistry
- Pharmaceutical Analysis
Context:
- Cetirizine hydrochloride is a widely used antihistamine.
- Understanding its conformational dynamics is crucial for drug formulation and efficacy.
- NMR spectroscopy provides insights into molecular structure and dynamics.
Purpose:
- To investigate the Nuclear Magnetic Resonance (NMR) phenomena of cetirizine hydrochloride.
- To assign all proton and carbon signals in the NMR spectra.
- To elucidate the conformational behavior of cetirizine hydrochloride in solution.
Summary:
- 1D and 2D NMR spectra of cetirizine hydrochloride were recorded in DMSO-d6 at varying temperatures and with D2O addition.
- At room temperature, piperazine and attached groups showed multiple NMR signals, indicating conformational exchange.
- Signal coalescence/narrowing upon heating or D2O addition suggests temperature-dependent dynamics and stabilization of a specific conformation.
Impact:
- Reveals the presence of multiple conformations of cetirizine hydrochloride in solution at room temperature.
- Demonstrates that NMR can distinguish between fast conformational exchange and stable conformations.
- Provides a foundation for further studies on drug-receptor interactions and stability.