Efficient analysis of pharmaceutical drug substances and products using a solid-state NMR CryoProbe

Solid-state nuclear magnetic resonance (ssNMR) is a high-resolution and versatile spectroscopic tool for characterizing pharmaceutical solids. However, the inherent low sensitivity of NMR remains a significant challenge in the analysis of natural abundance drug substances and products. Here, we report, for the first time, the application of a CPMAS CryoProbe™ to improve the sensitivity of 13C and 15N detection by approximately 5 to 6 times for solid-state analysis of a commercial pharmaceutical drug posaconazole (POSA). The sensitivity enhancement enables two-dimensional (2D) 13C–13C and 1H–15N correlation experiments, which are otherwise time-prohibitive using regular MAS probes, for resonance assignment and structural elucidation. These polarization transfer and correlation experiments reveal drug–drug and drug–polymer interactions in amorphous POSA and its amorphous solid dispersion formulation. Our results demonstrated that the CPMAS CryoProbe™ can be widely applied for routine pharmaceutical analysis and advanced structural investigations with significantly enhanced efficiency and throughput.