The aim of this study was to compare the applicability of inulin, its surface-active derivative (Inutec® SP1), and polyvinylpyrrolidone (PVP) as carriers in high drug load solid dispersions (SDs) for improving the dissolution rate of a range of lipophilic drugs (diazepam, fenofibrate, ritonavir, and efavirenz). The SDs were prepared by spray freeze-drying. Scanning electron microscopy showed that the obtained samples were highly porous spherical particles. Modulated differential scanning calorimetry showed that the drugs incorporated in these carriers were fully or partially amorphous. The solubility of the drugs in solutions of the different carriers was increased in an order: inulin 2.3 kDa < PVP K30 ≪ Inutec® SP1. The dissolution behavior of SD tablets was evaluated. Inutec® SP1-based SD tablets showed the best performance followed by PVP- and inulin-based SD tablets. The superior dissolution behavior of the drugs from Inutec® SP1-based SDs could be ascribed to its surface-active nature. In addition, Inutec® SP1-based SD tablets gave good physical stability at 20 °C/45% relative humidity (RH) and 40 °C/75% RH for 3 months.
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