Design & Synthesis of A Few Pharmaceutical Cocrystals/Salts by Crystal Engineering Approach and Study of Their Physicochemical Properties

Abstract

The pharmaceutical cocrystal of an active pharmaceutical ingredient with GRAS or non-GRAS compounds offers an opportunity to develop a new drug product with improved physicochemical properties. Pharmaceutical cocrystal exhibits better physicochemical properties such as solubility, stability, dissolution, melting point, crystal habit, compressibility, friability etc. without altering the biological activity of drug compounds. In the last two decades, numerous research activities have been carried out to develop the new drug products of BCS Class II and BCS Class IV drug ingredients by cocrystallization techniques. The result showed remarkable increment in the solubility and dissolution rate of BCS Class II and IV drug ingredients. In this context, a series of active pharmaceutical ingredients have been chosen for the present work which is having poor or high aqueous solubility and permeability. All the active ingredients chosen in the study are screened for salt/cocrystallization experiments by crystal engineering approach with various GRAS and non-GRAS compounds. Solution crystallization and liquid-assisted grinding approach are followed for the cocrystallization experiments. The newly synthesized salts/cocrystals were characterized by various spectroscopic (FT-IR, NMR, and UV-Vis), thermal (DSC and TGA), and PXRD techniques. The crystal structure of the synthesized salts/cocrystals were determined by SC-XRD techniques. Aqueous solubility (equilibrium solubility) was measured for the cocrystal/salt of BCS class II drug by UV-Vis spectroscopy and compared the results with API alone. In all the five series, the stability of the synthesized salts/cocrystals were evaluated. In some cases, hygroscopicity study at accelerated humidity condition was performed to demonstrate the non-hygroscopicity of the synthesized cocrystal/salt. In few cases, isostructurality of the synthesized salt/cocrystal was described based on the SC-XRD analysis. Further, in one chapter DFT calculations were performed for the synthesized salt/cocrystal to support the crystal structure data determined from the SC-XRD analysis.