Clarification of the Dissolution Mechanism of an Indomethacin/Saccharin/Polyvinylpyrrolidone Ternary Solid Dispersion by NMR Spectroscopy

Here, an indomethacin (IMC)/saccharin (SAC)/polyvinylpyrrolidone (PVP) ternary solid dispersion (SD) prepared by spray-drying was characterized to clarify its dissolution mechanism. Solid-state NMR spectroscopy revealed that IMC and SAC in the ternary SD interacted via hydrogen bonding in a similar manner as that in the IMC/SAC co-crystal. Initial IMC dissolution from the ternary SD was slower than that from the binary SD, although IMC supersaturation was maintained for a relatively longer time in the ternary SD. Solid- and solution-state NMR measurements for dispersed particles in the dissolution test revealed that the particle for IMC/PVP binary SD was composed of amorphous IMC dispersed in PVP matrix and alpha-form IMC. In contrast, the particles for the ternary SPD was composed of amorphous IMC dispersed in PVP matrix and IMC/SAC co-crystals. Scanning electron microscopy indicated that in the binary SD, amorphous IMC microfiber-gel was generated on the surface of particles after the dissolution test, preventing amorphous IMC from contacting with water. In contrast, in the ternary SD, IMC/SAC co-crystals were generated on the surface of particles, and intermediate spaces were formed on the surface, which allowed water intrusion into the particles and continuous dissolution of IMC. (C) 2020 American Pharmacists Association (R). Published by Elsevier Inc. All rights reserved.