Processing Pharmaceutical Compounds Using Dense Gas Technology

Abstract

Dense gas techniques, which utilize the properties of fluids in the vicinity of the critical point, are increasingly being used for the processing of pharmaceuticals. Dense gases are unique solvents that can be used for extractions, chromatographic separations, and chemical syntheses because of their liquidlike solvation power and gaslike mass-transfer properties. The processes can be conducted at moderate temperatures and are thus suitable for many heat-labile compounds such as proteins, biocompatible polymers, and pharmaceuticals. The products formed by densegas processes are generally free of residual solvent. Recent applications of dense gas techniques have focused on micronization; crystallization of high-purity particles; sterilization; and drug formulations, including the formation of liposomes and drug coatings. The following review presents examples of drug extraction, separation, synthesis, sterilization, and particle formation and demonstrates the broad application of dense gases for drug formulation purposes in the pharmaceutical industry.

Fractioned High Pressure Extraction of Anthocyanins from Elderberry (Sambucus nigra L.) Pomace

“…In anthocyanin extraction, this fact can be an important advantage: there will be a temporary reduction in the extraction medium pH value, and this will increase anthocyanin stability and cell membrane permeability, leading to higher diffusivities (Türker and Erdoğdu 2006;Norton and Sun 2008). Moreover, it also can inactivate unwanted enzymes (Kamat et al 1995;Norton and Sun 2008) and microorganisms (Foster et al 2003) that may destroy these pigments (Delgado-Vargas and Paredes-López 2003;GarciaPalazon et al 2004). On the other hand, the presence of undesired compounds in several vegetal matrixes, which may be coextracted or which may interfere negatively with the extraction of desired substances, decreasing extraction yield and selectivity, is a typical situation in natural products extraction methodologies (conventional and supercritical).…”

High‐pressure NMR characterization of triacetyl‐β‐cyclodextrin in supercritical carbon dioxide

“…[6,7] Particularly important is the fact that scCO 2 can be easily separated from products by simple decompression of the system, resulting in a solvent-free product eliminating the need for energy intensive drying steps to remove solvents, [8] and the possibility of processing heat-sensitive molecules. [9] The use of scCO 2 as a reaction medium is often limited by its poor solvent strength with respect to conventional organic solvents. [10] As natural CDs are insoluble in scCO 2 , reported examples of CD complexes in this medium are produced by mixing the physical mixture of the CD and the guest molecule in batch, or in continuous mode, by placing both compounds in separated reactors, and passing a stream of scCO 2 saturated with the drug through the CD matrix.…”

Bioseparation of Nutraceuticals Using Supercritical Carbon Dioxide

“…Another benefit of supercritical technology over conventional solvent extracts is longer shelf life due to inactivation of microorganisms and spores throughout the high pressure treatment and the depressurization step. Such SC-CO 2 treatment is also being looked at as a sterilization technique for various applications, including pharmaceuticals and medical devices (Foster et al 2003).…”