Physicochemical properties and oral bioavailability of ursolic acid nanoparticles using supercritical anti-solvent (SAS) process

► Nanoscale ursolic acid (UA) was made by a supercritical antisolvent process. ► Mean particle size of processed UA is 139.2±19.7nm, irregularly spherical. ► Dissolution rate and oral bioavailability of nanoscale UA increased significantly. The objective of the study was to prepare ursolic acid (UA) nanoparticles using the supercritical anti-solvent (SAS) process and evaluate its physicochemical properties and oral bioavailability. The effects of four process variables, pressure, temperature, drug concentration and drug solution flow rate, on drug particle formation during SAS process, were investigated. Particles with mean particle size ranging from 139.2±19.7 to 1039.8±65.2nm were obtained by varying the process parameters. The UA was characterised by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, specific surface area, dissolution test and bioavailability test. It was concluded that physicochemical properties and bioavailability of crystalline UA could be improved by physical modification, such as particle size reduction and generation of amorphous state using SAS process. Further, SAS process was a powerful methodology for improving the physicochemical properties and bioavailability of UA.