51. Thakur, R.; Gupta, Ram B. “Production of Hydrocortisone Micro- and Nano-particles using Supercritical Antisolvent with Enhanced Mass Transfer, Chem. Eng. Comm., 193:293–305, 2006.
Supercrit. anti-solvent pptn. 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 supercrit. anti-solvent process but uses a reflecting horn surface that vibrates at 20 kHz frequency, which enhances the mass transfer of the solvent to supercrit. 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 W (to ultrasonic transducer), HC fibers of an av. length of .apprx.81 mm and an av. diam. of .apprx.6 mm are obtained. Upon increasing the power supply to 120 W, which enhances mass transfer, particles of av. size as low as 180 nm are obtained. Intermediate particle size and morphol. are easily obtained by adjusting the power supply to the desired intermediate value. The obtained powder is free of impurities and is mostly amorphous.