 |
 |
Microscopic beads mimic body's drug release system LONDON (July 30, 1998 09:10 a.m. EDT http://www.nandotimes.com) - Scientists have developed microscopic beads that may be able to carry and release drugs directly on tumors by mimicking the body's own drug release system. The beads, devised by researchers at Duke University in North Carolina, are made of polymer hydrogel that is similar to the material used in contact lenses and a protective outer coating. When the polymer swells it bursts and releases the drug. In a letter in the science journal Nature on Wednesday, the researchers said that although the system has not been proven in trials, early tests have shown that the beads can be leak-proof carriers of the potent anti-cancer drug doxorubicin. "Nature packages its drugs in polymers," David Needham, an associate professor of mechanical engineering and materials science, said in a telephone interview. The lipid layer is impermeable to sodium so the drug is trapped inside and the bead can patrol the bloodstream in search of tumors until it is triggered to release the drug. This could be done by external heat which could break down the coating or high-pitched ultrasound waves beamed into the body through the skin. "This system could find use for the triggered release of encapsulated drugs in the body," the researchers said. Needham, Kiser and Mark Dewhirst, a radiation oncologist,are now working on the best way to activate the polymer explosion so it delivers the drug when and where it is needed most in tumors. Unlike standard chemotherapy treatment that kills healthy as well as malignant cells in a very scattered approach, polymers could potentially carry drugs directly to the tumor. "Any molecule that has a therapeutic activity or an imaging feature could be trapped in this hydrogel," said Needham. "We envision this being an intravenous injection." Ronald Siegel of the University of California in San Francisco stressed in a commentary in Nature that the beads still need to tested on animals but he praised the achievement. "By a clever combination of polymer-gel science and lipid chemistry, they have constructed a granule mimic that can store a drug for a desired period and rapidly release it when properly stimulated," he said. In addition to carrying anti-cancer drugs, Needham and his colleagues said the system could also be used for a vaccine. "It's a hydrogel that can bind materials, coated with a bilayer to release it. It mimics the (natural) secretory granule. How we would use it is now the focus of our research," he added. By Patricia Reaney, Reuters Copyright 1998 Nando.net Copyright 1998 Reuters News Service a new voice - http://www.newcountry.nu/pd/members/janet/index.htm janet paterson - 51/10 - endocarb/selegiline/fluoxetine almonte/ontario/canada - [log in to unmask]