Use of Time-Domain NMR for H T Relaxation Measurement and Fitting Analysis in Homogeneity Evaluation of Amorphous Solid Dispersion.

This study examined the usefulness of H T relaxation measurements for evaluating the homogeneity of amorphous solid dispersion (ASD). Indomethacin and polyvinylpyrrolidone were used to prepare two kinds of ASDs. One was inhomogeneous ASD (ASD) prepared by a melt-quenching method, and the other was homogeneous ASD (ASD) prepared by a solvent evaporation method. The T relaxation was measured by the time-domain NMR (TD-NMR) technique using a low-field NMR system. Curve-fitting analysis of T relaxation plots was conducted using the Akaike information criterion. This fitting analysis revealed that the T relaxation of ASD and ASD was biphasic and monophasic, respectively. ASD and ASD were inhomogeneous and homogeneous on a nanometer scale, respectively, considering the spin diffusion of H nuclei. These T results were consistent with the Raman mapping of ASDs. From the fitting analysis of H T relaxation, we conclude that TD-NMR is a promising technique for evaluating ASD homogeneity.