Manufacture of submicron drug particles with enhanced dissolution behaviour by rapid expansion processes

In the case of pharmaceutical substances the particle size is quite important since it can limit the bioavailability of poorly soluble drugs. As an example we can refer to the data obtained for Griseofulvin. In 1962 Atkinson has studied the concentration of the drug in the blood, taken from healthy volunteers at given intervals of time after dosing, as a function of its specific area. The quantity absorbed for a particle size of 2.7 μm is twice as high compared with a particle size of 10 μm. The present article gives a survey of published knowledge about particle and product design with focus on the RESS process and some promising modifications of this technique. Experimental results confirm that each of these processes is a promising technique for the formation of submicron particles (≤100 nm) and that the improved dissolution behaviour is influenced by particle size, surface area, and wettability of the processed powders as well as by the pH-value of the dissolution media.