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Insoluble Salt of Memantine with a Unique Fluorescence Phenomenon
Wenjie Kuang1, Jian Liu1, Xia Lin2
1State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, P. R. China.
Abstract:
Alzheimer's disease is a chronic disease, and the long-term treatment of chronic diseases has always been a concern. Memantine (Mem) is approved by the US Food and Drug Administration for the treatment of moderate to severe Alzheimer's disease. In this study, reactions of memantine (Mem) with pamoic acid (Pam) were carried out to form insoluble salts (Mem-Pam). Four polymorphic forms (Forms I-IV) of Mem-Pam were successfully obtained through polymorphic screening, which were systematically characterized by X-ray powder diffraction (PXRD), thermal analysis (TGA and DSC), single-crystal X-ray diffraction (SXRD), and solid-state fluorescence. Compared with the hydrochloride form, the dissolution and release rates of these four forms are lower. The presence of pamoic acid reduces the release rate of memantine and makes it possible to achieve a sustained release of the drug. Interestingly, because of the presence of memantine, each polymorphic solid crystal of Mem-Pam has unique fluorescence emission. Therefore, memantine and pamoic acid have a synergistic effect on the fluorescence performance and can be expected to be used for real-time monitoring in continuous and controlled release drug delivery systems. In addition, the polymorphic solid crystals also exhibit reversible mechanochromic luminescence under the fumigation of acetonitrile vapor, which has a guiding role in the fluorescence design and synthesis of Pam substances and is expected to be used for information security, visual inspection of organic substances, etc.
Insights
Researchers developed four new solid forms of memantine (Mem) with pamoic acid (Pam) for Alzheimer's disease treatment. These Mem-Pam forms offer sustained drug release and unique fluorescence properties for potential monitoring applications.
Area of Science:
- Pharmaceutical Chemistry
- Materials Science
- Drug Delivery
Background:
- Alzheimer's disease (AD) necessitates long-term treatment strategies.
- Memantine (Mem) is an FDA-approved drug for moderate to severe AD.
- Developing novel drug formulations can improve therapeutic outcomes.
Purpose of the Study:
- To synthesize and characterize novel solid forms of memantine pamoate (Mem-Pam).
- To evaluate the drug release profiles of these new forms.
- To investigate the fluorescence properties of Mem-Pam for potential applications.
Main Methods:
- Polymorphic screening to obtain four Mem-Pam forms (I-IV).
- Characterization using X-ray powder diffraction (PXRD), thermal analysis (TGA, DSC), and single-crystal X-ray diffraction (SXRD).
- Solid-state fluorescence spectroscopy and mechanochromic luminescence testing.
Main Results:
- Four distinct polymorphic forms of Mem-Pam were successfully synthesized.
- Mem-Pam forms exhibited lower dissolution and release rates compared to the hydrochloride form, enabling sustained release.
- Unique fluorescence emissions were observed in Mem-Pam crystals due to synergistic effects.
- Reversible mechanochromic luminescence was demonstrated under acetonitrile vapor.
Conclusions:
- Memantine pamoate offers a promising approach for sustained release of memantine.
- The synergistic fluorescence properties of Mem-Pam are suitable for real-time monitoring in drug delivery systems.
- The observed mechanochromic luminescence has potential applications in information security and material inspection.
