| Nanoparticles and new technologies enhance the bioavailability of poorly soluble drugs, writes Yann Bayeux at Pierre Fabre Medicament
Around two thirds of the products used in the pharmaceutical industry are in solid form, such as tablets and pills. Consequently, a lot of effort has been put into research on particle generation processes. The standard processes – crushing/milling and crystallisation/precipitation – are still the most commonly used. However, supercritical fluid (SCF) technologies present a new and interesting route for particle formation, which avoids most of the drawbacks of the traditional methods. Supercritical processes give micro or even nanoparticles with a narrow size distribution. They can also be used in co-process with excipients or host molecules like cyclodextrins.
USING SUPERCRITICAL CO2
The supercritical state is also known as the fourth state of matter. Above a certain critical temperature and pressure (30.7°C and 73.8 bar respectively for CO2), the boundaries between gas and liquid disappear. Beyond this critical point, the substance has the viscosity of a gas and the density of a liquid. Supercritical CO2 (scCO2) is the most commonly-used system in nanoparticle generation. The main reason is linked to the intrinsic solvent properties of the supercritical CO2: the viscosity of a gas, the density of liquid and the fact that the critical state of CO2 can be easily reached. The treatment is generally carried out at about 40°C and it allows us to handle temperature-sensitive molecules. Furthermore, CO2 is cheap, non-toxic, noninflammable, easily available and can also be recycled. Supercritical carbon dioxide is considered as a ‘green’ solvent; after depressurisation, it leaves no residue, unlike an organic solvent. |
