Polymorphic Characterization of Pharmaceutical Solids, Donepezil Hydrochloride, by ¹³C CP/MAS Solid-State Nuclear Magnetic Resonance Spectroscopy

Polymorphic Characterization of Pharmaceutical Solids, Donepezil Hydrochloride, by ¹³C CP/MAS Solid-State Nuclear Magnetic Resonance Spectroscopy

Donepezil hydrochloride is a reversible acetylcholinesterase inhibitor that is used in the treatment of Alzheimer’s disease to improve the cognitive performance. It shows different crystalline forms including hydrates. Therefore, it is very important to confirm the polymorphic forms in the formulations of pharmaceutical materials because polymorphs of the same drug often exhibit significant differences in solubility, bioavailability, processability and physical/chemical stability. In this paper, four different forms of donepezil hydrochloride were prepared and characterized using X-ray powder diffraction, Fourier transform infrared, and solid-state nuclear magnetic resonance (NMR) spectroscopy. This study showed that solid-state NMR spectroscopy is a powerful technique for obtaining structural information and the polymorphology of pharmaceutical solids.