Dissolution enhancement of sorafenib tosylate by co-milling with tetradecanol post-extracted using supercritical carbon dioxide

Sorafenib (SOR) is an important multikinase inhibitor for the treatment of cancers. It is commercially available (Nexavar from Bayer) in the form of sorafenib tosylate (SORt) due to its very low solubility. Studies have been made to further improve the dissolution behavior of the tosylate form (SORt), which could ultimately moderate the currently high daily dose. In the present study, SORt nanoparticles (SORt-NP) were prepared through a process that combined two industrially well-accepted techniques of co-milling and supercritical extraction. SORt was co-milled with hydrophilic polymers and tetradecanol, and the tetradecanol was post-extracted using supercritical carbon dioxide. The process enabled the formation of SORt-NP without using any toxic organic solvents, and the drug/excipient ratio (1:0.38) was substantially higher than determined in other studies (1:5.4-10). The enhanced dissolution behavior of SORt-NP was possible with an optimized number of milling cycles. Combining co-milling and supercritical extraction was able to form overall porous network structures with reduced crystallite size, which accelerated the dissolution of SORt-NP. The current method could be easily extended to other poorly soluble drugs as a general approach to improve their dissolution behaviors.