Aug. 31, 2001 New Brunswick/Piscataway - Polymers that may improve drug delivery or enhance cosmetic products were highlighted in a paper presented Monday, August 27 by Kathryn E. Uhrich, Rutgers associate professor of chemistry, at the 222nd national meeting of the American Chemical Society in Chicago, Ill.
ACS, which holds two national meetings a year, is the world's largest scientific society. The paper, "Designing Polymeric Micelles for Drug Transport," is a summary of Uhrich's work on unique polymers known as amphiphilic starlike macromolecules (ASMs).
These molecules act like tiny carrying cases for drugs and other types of oily or greasy molecules, such as fragrance oils, that don't dissolve easily in water. The ASMs make the drugs water-soluble so they can be readily transported through the skin, eyes, intestinal walls or any other body tissue.
Most drugs are hydrophobic and thus not easily soluble in the bloodstream, Uhrich explained. To make sure drugs get to their destination within the body, they are often delivered inside fatty globules known as liposomes. But liposomes aren't always good carriers because heat and enzymes can break them up and allow the drug to escape in an uncontrolled fashion.
Uhrich reports that adding a small amount of ASM polymer to the liposome solution resolves both the water solubility and drug control problems because it stabilizes the liposomes. "It appears that it takes only a small amount of the polymer to stabilize the liposomes," she says. "We're still not sure exactly how it works, but we're studying it."
Uhrich and her team have also found that by altering the polymer structure in certain ways, they can control the rate at which the drug is released. Designing polymers that are more "greasy" or more hydrophobic, will cause the drug to be released slowly, while a polymer that's less hydrophobic will release its drugs faster.
"We are reaching a point in our research where we believe we will be able to design the carrier to meet a drug's specific time-release requirements and make it stay in the bloodstream for a long or short period of time so that the patient gets the maximum benefits of the drug," she said.
So far, Uhrich's research team has tested the polymer systems on several molecules, including beta-blocker drugs used to treat heart disease and antibiotics. "We are searching for the best match between the polymer and the drug, where the drug is released over a desirable time period," she noted.
Uhrich has latched onto another unique property of the polymers – their ability to turn liposomes from opaque substances into crystal-clear ones -- to develop crystal-clear beauty products. The team has found that adding a small amount of polymer can change the liposome solution from opaque to clear, a "very desirable commodity in the world of cosmetics right now," she noted, "judging from the number of cosmetic companies that have expressed interest in the concept.
"Cosmetics weren't my first goal," adds Uhrich, "but it makes sense. The same properties needed for transporting drugs -- such as biocompatibility and water solubility -- are needed for beauty aids. If you can use polymers to carry 'greasy' drugs within your body, why not use them to carry 'greasy' dyes or fragrances outside the body?"
At present, Uhrich's polymers are targeted at drugs and cosmetics, but many other potential uses exist for the ASM polymer's powers. "They could work with anything that's greasy or oily that you may want to make into a water solution or make clear," Uhrich notes.
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