Local atomic structure determination of the amorphous verapamil HCl drug

Author(s)

Bezzon, Vinicius D. N. ; Ferreira, Fabio F. ; de Lima, Joao C.

• Document type: Journal article
• Source: Journal of Non-Crystalline Solids; v. 565, p. 10-pg., 2021-05-14.

Abstract

We investigate the local atomic structure of verapamil hydrochloride in the amorphous state (a-VRPH) using the pair distribution function (PDF) and Reverse Monte Carlo (RMC) methods. We obtain the a-VRPH sample from its crystalline counterpart (c-VRPH) using the solvent evaporation technique. From the measured X-ray powder diffraction (XRPD) data for a-VRPH and c-VRPH, two total structure factors S(Q) are derived, and Fourier transforming them, two total reduced distribution functions, gamma(R), are obtained. We refine the XRPD pattern of cVRPH using the Rietveld method to confirm the sample's crystal structure is the pure c-VRPH. The partial Sij(Q) factors and PDF functions are simulated based on the VRPH crystal structure found in the Cambridge Structural Database (R) (CSD). The PDF and RMC analyses allow us to observe some similarities between a-VRPH and c-VRPH at the intramolecular level and the main differences at the intermolecular level induced by the amorphization process. (AU)

• FAPESP's process: 18/11990-5 - Local structure characterization and stability of amorphous systems
• Grantee: Vinícius Danilo Nonato Bezzon
• Support Opportunities: Scholarships in Brazil - Post-Doctoral