Solid State NMR Study of the Mixing Degree Between Ginkgo Biloba Extract and a Soy-Lecithin-Phosphatidylserine in a Composite Prepared by the Phytosome® Method

The Physical Stability of Felodipine and Its Recrystallization from an Amorphous Solid Dispersion Studied by NMR Relaxometry

The ¹H nuclear magnetic resonance (NMR) relaxometry method was applied to investigate the physical stability of an active pharmaceutical ingredient (API) and, for the first time, its recrystallization process in an amorphous solid dispersion system (ASD). The ASD of felodipine and polyvinylpyrrolidone (PVP) was prepared using the solvent evaporation method in a mass ratio of 50:50. In the first stage of the study (250 days), the sample was stored at 0% relative humidity (RH). The recovery of magnetization was described by one-exponential function. In the second stage (300 days in 75% relative humidity), the recrystallization process of felodipine was studied, showing in the sample three components of equilibrium magnetization related to (i) crystalline felodipine, (ii) water, and (iii) felodipine and PVP remaining in the ASD. The study shows that the ¹H NMR relaxometry method is a very useful tool for analysing the composition of a three-phase system mixed at the molecular level and for the investigation of recrystallization process of API in amorphous solid dispersion system.

NMR technique and methodology in botanical health product analysis and quality control

Botanicals have played an important role in maintaining human health and well-being throughout history. During the past few decades in particular, the use of botanical health products has gained more popularity. Whereas, quality, safety and efficacy concerns have continuously been critical issues due to the intrinsic chemical complexity of botanicals. Chemical analytical technologies play an imperative role in addressing these issues. Nuclear magnetic resonance (NMR) spectroscopy has proven to be a powerful and useful tool for the investigation of botanical health products. In this review, NMR techniques and methodologies that have been successfully applied to the research and development of botanical health products in all stages, from plants to products, are discussed and summarized. Furthermore, applications of NMR together with other analytical techniques in a variety of domains of botanical health products investigation, such as plant species differentiation, adulteration detection, and bio-activity evaluation, are discussed and illustrated with typical examples. This article provides an overview of the potential uses of NMR techniques and methodologies in an attempt to further promote their recognition and utilization in the field of botanical health products analysis and quality control.

NMR relaxometry in an investigation of the kinetics of the recrystallization of a three-phase system

The method of ¹H Nuclear Magnetic Resonance (NMR) relaxometry is applied to investigate the kinetics of the recrystallization of an active pharmaceutical ingredient (felodipine) from the amorphous phase of its physical mixture with a polymer (polyvinylpyrrolidone, PVP). Comparison of the recrystallization results obtained for amorphous felodipine and its mixtures with PVP shows that the recrystallization process of API is faster in the mixtures and depends on the content of water in the system. The free induction decay (FID) for protons that were detected are composed of three components, and the loss of water from PVP strongly influences the part characterized by the longest spin-spin lattice relaxation time. Analysis of the FID of the physical mixture indicates that the content of water does not change during the recrystalization process. The study shows that the T₁¹H NMR relaxometry method is very useful for analysing the composition of a three-phase mixture and the recrystallization process.