Story by Dann Hayes, (913) 864-8855 E-mail: [email protected]
KU RESEARCHER FINDS REPLACEMENT FOR SOLVENTS
LAWRENCE ã A solvent used in the food-processing trade is expected to help the pharmaceutical industry replace environmentally unfriendly and expensive solvents in the manufacture of drugs.
By using supercritical carbon dioxide, or CO2, in the pharmaceutical process, researchers at the University of Kansas have successfully replaced some chemical solvents. A supercritical fluid exists as neither a gas nor a liquid, but is something between the two that can exist only at a certain temperature and pressure.
≥Solvents are considered essential to the manufacture of drugs,≤ said Bala Subramaniam, Sharp professor of chemical and petroleum engineering at KU. ≥Theyπre used in the reactions that create most active drug compounds and, later in the process, to separate out the pure, active ingredients so they can be used to create finished drug products, such as tablets and intravenous solutions.≤
But many solvents used in pharmaceutical processes are unfriendly to the environment, Subramaniam said. An example is methylene chloride, which can no longer be used in the United States because itπs environmentally harmful, with serious hazardous-waste-disposal problems. It also leaves unacceptable residues on pharmaceutical products.
According to Subramaniam, supercritical CO2 can replace traditional solvents because at certain pressures and temperatures it behaves very much like them.
≥We have proved that supercritical CO2 is quite good at separating drug particles from solutions and recrystallizing them into discrete particles,≤ he said. ≥This leaves no detectable trace of residues unacceptable to regulatory agencies.≤
The food-processing industry has used supercritical CO2 for decades, such as in the decaffeination of coffee beans.
A patent has been filed on the supercritical CO2 recrystallization technique.
≥It is essentially a process to produce drug particles with desired sizes,≤ Subramaniam said. ≥The starting point is a solution in which the drug is dissolved. This solution is sprayed as droplets into a chamber containing compressed carbon dioxide, which selectively extracts the solvent from the spray, causing the drug to fall out of solution as fine particles.≤
This process has several advantages over traditional techniques, he said. It replaces the solvents previously used with environmentally benign supercritical CO2 and allows for better control of particle size distribution, which is important for effective therapy.
The particle formation process that Subramaniam and his team have invented could also be applied in other areas of material processing, such as polymer production. However, the focus of research at KU has been on the pharmaceutical industry.
≥There are others out there working on these techniques,≤ he said. ≥But weπve crested the wave, and we hope to stay on top.≤
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