Key Applications of Supercritical CO₂ Equipment in the Pharmaceutical Industry

Supercritical CO₂ equipment is widely used in the pharmaceutical industry. Its operating principle is highly ingenious: carbon dioxide reaches a supercritical state under specific conditions (temperature above 31.1°C and pressure above 7.37 MPa). In this state, CO₂ exhibits both liquid-like and gas-like properties, combining strong solubility with high diffusivity.

This technology is particularly suitable for extracting active ingredients from traditional Chinese medicines. For instance, when extracting volatile oils from herbs such as mugwort and zedoary turmeric, conventional methods often lead to loss of active components. In contrast, supercritical CO₂ extraction can be performed at low temperatures, increasing oil yield by 4–5 times. For example, in the extraction of peppermint volatile oil, a yield of 3.20% was achieved, significantly higher than the 0.84% obtained by steam distillation, while also preserving better bioactivity.

For highly polar compounds such as alkaloids and flavonoids, ethanol can be added as an entrainer to improve extraction efficiency. The extraction of lignans from Schisandra chinensis is a typical case, achieving a yield of 2.929%, which is 5.4 times higher than that of conventional methods. In the extraction of compound herbal medicines, such as cinnamaldehyde from Huoxue Babu Plaster, the extraction rate reached 80.13%, demonstrating excellent performance.

In pharmaceutical formulation, supercritical CO₂ technology addresses several key challenges. One application is drug micronization. For poorly water-soluble drugs, ultrafine particles of 1–2 microns can be prepared using methods such as RESS or GAS, significantly improving bioavailability. This technology is especially advantageous for drugs with low melting points or waxy characteristics, such as ibuprofen, where conventional grinding often causes particle adhesion.

Another application is in hot-melt extrusion, which can be regarded as a second-generation hot-melt extrusion technology. CO₂ acts as a temporary plasticizer, reducing the processing temperature by 30–65°C. This is particularly important for protecting heat-sensitive active ingredients. For example, when p-aminosalicylic acid is co-processed with ethylcellulose, the degradation rate of the active ingredient decreases from 17% to 5%. Moreover, the resulting foamed material is easier to mill, increasing the yield from 59% to 96%.

In analytical testing, supercritical fluid chromatography (SFC) offers significant advantages, including rapid analysis and low sample consumption. It is particularly suitable for separating chiral drugs. For instance, this technology performs effectively in separating cortisone and dexamethasone isomers.

From an environmental perspective, this technology is truly green. It replaces toxic solvents such as dichloromethane and hexane, and CO₂ can be recycled, resulting in lower energy consumption compared to conventional processes. For example, in hops extraction, CO₂ is fully recycled, making the process both economical and environmentally friendly.

Certainly, the technology also has limitations. Equipment costs are relatively high, continuous production remains challenging, and the extraction efficiency for highly polar compounds needs further improvement. However, with ongoing technological advances, supercritical CO₂ technology holds great potential, particularly in the extraction of compound herbal medicines and the development of nano-formulations.

In summary, supercritical CO₂ technology offers an efficient and green pathway for the pharmaceutical industry. Although the initial investment is relatively high, the long-term benefits in terms of product quality and environmental sustainability make it worthwhile. Based on our practical experience in recent years, the advantages of this technology are evident, and we believe it will see broader adoption in the future.