Molecular Salts of Anesthetic Lidocaine with Dicarboxylic Acids: Solid-State Properties and a Combined Structural and Spectroscopic Study

Four lidocaine molecular salts of
dicarboxylic acids (oxalic, fumaric,
malonic, and succinic) were synthesized and characterized by a combined
use of X-ray powder and single-crystal diffraction, differential scanning
calorimetry, Fourier transform infrared spectroscopy (FT-IR), and
solid-state NMR (1H MAS and CRAMPS, and 13C
and 15N CPMAS): all molecular salts show a dramatic increase
in their melting point with respect to both lidocaine and lidocaine
hydrochloride, and a higher dissolution rate and thermodynamic solubility
in physiological solution with respect to the free base.

通过结合使用X射线粉末衍射和单晶衍射、差示扫描量热法、傅里叶变换红外光谱（FT-IR）以及固态核磁共振（1H MAS和CRAMPS，以及13C和15N CPMAS）对四种羧酸二盐（草酸、富马酸、丙二酸和丁二酸）的利多卡因分子盐进行了合成与表征：所有分子盐相较于利多卡因及其盐酸盐均表现出显著的熔点升高，在生理溶液中的溶解速率和热力学溶解度亦相对游离碱有所提升。