New Approaches to the Characterization of Drug Candidates by Solid‐StateNMR

Abstract

Solid‐state NMR (SSNMR) spectroscopy has been found to be very useful technique for pharmaceutical development. This technique is currently applied for the study of pharmaceutical solids, ranging from detailed structural studies of active pharmaceutical ingredients (APIs) forms to analysis of complex drug products and formulations. The study suggests that solid‐state structure of a pharmaceutical product can influence its properties, manufacturability, and stability. It is essential to regulate and control over solid‐state structure and subsequent properties. The studies show that SSNMR is closely related to the widely used technique of solution‐state NMR and possesses many of the same features. Further the study concludes that field of pharmaceutical SSNMR continues to advance at a rapid rate and will develop new molecular classes and new formulations and delivery modes in near future.

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“…The possibility of phase separation in the 1:2 tenoxicam– l ‐arginine SDD was assessed using 13 C‐detected 1 H T 1 and T 1ρ relaxation measurements at a single temperature (273 K). 1 H T 1 measurements can detect phase separation if present but cannot directly prove phase association as different phases within a mixture can have coincidentally similar 1 H T 1 relaxation times 48–49. It was previously shown that multiple peaks within a single 13 C‐detected 1 H T 1 saturation‐recovery experiment can be used to estimate a confidence interval (CI), which is useful for determining the likelihood that a particular resonance with a slightly different 1 H T 1 value is statistically meaningful and thus likely to be a separate phase 49,70.…”

“…In the present work, the SDDs are characterized with DSC, X‐ray powder diffraction (XRPD), IR spectroscopy, scanning electron microscopy (SEM), and solid‐state nuclear magnetic resonance (SSNMR). SSNMR is a particularly powerful tool for studies of amorphous materials and interactions between molecular species in formulated drug products 45–48. Recently developed approaches to the study of molecular association using two‐dimensional (2D) SSNMR and spin diffusion effects are applied to probe intermolecular interactions and gain insight into the solid‐state structure of the SDDs 49.…”

Chapter 2. Solid‐State NMR in Drug Discovery and Development

“…Specialized lineshape fitting routines are used to extract anisotropic parameters and obtain the principal components of tensors of interest, such as the fits shown in Figures 2.1, 2.2 and 2.3. [121][122][123] More details about quantitative processing of SSNMR data for drug development applications, including quantitative spectral analysis, deconvolution and nonlinear fitting of relaxation data, can be found elsewhere. 123 …”

“…[121][122][123] More details about quantitative processing of SSNMR data for drug development applications, including quantitative spectral analysis, deconvolution and nonlinear fitting of relaxation data, can be found elsewhere. 123 …”

“…213,214 A recent review that covers SSNMR studies of excipients in more detail is presented elsewhere. 123 Basic 13 C CP-MAS spectra of many common organic and polymeric pharmaceutical excipients have also been compiled. 215 The study of pharmaceutical excipients also offers unique opportunities for multinuclear SSNMR studies.…”