Production of hydrocortisone micro- and nano-particles using supercritical anti-solvent with enhanced mass transfer

Supercritical anti-solvent precipitation with enhanced mass transfer (SAS-EM) is used for the formation of particles of hydrocortisone (HC), an anti-inflammatory drug. This technique is similar to the supercritical anti-solvent process but uses a reflecting horn surface that vibrates at 20 kHz frequency, which enhances the mass transfer of the solvent to supercritical fluid anti-solvent, reducing the growth of the particles. Controllable sizes and morphologies of HC particles are obtained using the SAS-EM process. At a power supply of 0 watts (to ultrasonic transducer), HC fibers of an average length of similar to 81 mu m and an average diameter of similar to 6 mu m are obtained. Upon increasing the power supply to 120 watts, which enhances mass transfer, particles of average size as low as 180 nm are obtained. Intermediate particle size and morphology are easily obtained by adjusting the power supply to the desired intermediate value. The obtained powder is free of impurities and is mostly amorphous.