Characterization of multicomponent crystal formed between indomethacin and lidocaine

Abstract

Purpose: Crystalline complex was formed between indomethacin (IDM) and lidocaine (LDC) at molar ratio 2:1 from ethanol solution. The purpose of this study was elucidation of an interactive manner between IDM and LDC in ethanol solution and mechanism of the complex formation through solid state as well as liquid state. Methods: The chemical and physical nature of the complex was clearly elucidated by the alliance of powder X-ray diffractometry, differential scanning calorimetry, and infrared spectroscopy. The complex was also formed via solid-state reaction by cogrinding and heating treatment without any solvent. Results: The complexation process was estimated to be as follows: (i) mixing and contact of two components, (ii) disorder of crystalline LDC by grinding or fusion, and then (iii) crystal growth by heating. In addition, 1H-NMR coupled with microchanneled cell for synthesis monitoring revealed that a primary interactive force between IDM and LDC molecule was coulomb energy.

Key words:

• Crystal
• indomethacin
• lidocaine
• multicomponent
• pharmaceutical salts

Acknowledgments

This work was supported in part by a grant from the ‘Academic Frontier’ Project for Private Universities: matching fund subsidy from MEXT (Ministry of Education, Culture, Sports, Science, and Technology) 2007–2009 in Japan. The authors thank Dr. Yutaka Takahashi and Dr. Satoshi Sakurai of JEOL Ltd. (Japan) for the MICCS-NMR measurements. The authors also thank Ms. Misa Kenmotsu for her excellent technical assistance.

Declaration of interest: The authors report no conflicts of interest.