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Updated: May 12, 2026

A Package of Established Analytical Tools to Investigate the Solid-State Alteration of Lipid-Based Excipients
Published on: August 9, 2022
Physicochemical characterization of felodipine-kollidon VA64 amorphous solid dispersions prepared by hot-melt
Yuejun Song1, Lianyan Wang2, Ping Yang3
1College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China; Laboratory of Magnetic Resonance Spectroscopy and Imaging, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of sciences, Suzhou 215123, China.
Abstract:
To improve the dissolution and hence the oral bioavailability, amorphous felodipine (FEL) solid dispersions (SDs) with Kollidon® VA 64 (PVP/VA) were prepared. Hot-melt extrusion was employed with an extruding temperature below the melting point (Tm ) of FEL. X-ray powder diffraction (XRPD) and (13) C CP/MAS nuclear magnetic resonance (NMR) measurements show that the extrudates are amorphous. The intermolecular interaction between FEL and PVP/VA in SDs was investigated by Fourier transform infrared spectroscopy, (15) N CP/MAS NMR, and (1) H high-resolution MAS NMR. Furthermore, a single glass transition temperature (Tg ) was detected by differential scanning calorimetry in addition to a single (1) H T1 or T1rho relaxation time detected by (13) C NMR signals. These results confirm that the extrudates contain FEL dispersed into the polymer matrix at a molecular level with no detectable phase separation. This molecular-scale mixing results in a significantly faster dissolution rate compared with the pure crystalline FEL. Additionally, the molecular-scale mixing prevents the amorphous drug from recrystallizing even after being stored at 40°C/75% Relative Humidity for 2 months.
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