sealPurdue News

December 2000

Gel may cut doses for some medications

WEST LAFAYETTE, Ind. – A material invented at Purdue University is showing promise as a drug-delivery system that might replace some multiple-dose medications with a single daily formulation.

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Kos Pharmaceuticals Inc. of Miami, Fla., has signed a license from the Purdue Research Foundation's Office of Technology Commercialization to develop the material for a "gastric-retention" drug-delivery system.

The material, called "superporous hydrogels," expands dramatically when immersed in water. Oral drug delivery formulations made from the gels would swell rapidly in the stomach, causing medications to move more slowly from the stomach to the intestines.

Because the medications would remain in the stomach longer, they would be absorbed more efficiently by the body. Such a system might make it possible to take certain medications only once daily, instead of three or more times a day, said Kinam Park, a professor of pharmaceutics and biomedical engineering at Purdue.

Unlike other gels being tested for drug delivery, the superporous hydrogels swell to hundreds of times their dehydrated form within a matter of seconds, said Park, the gels' inventor.

Conventional hydrogels of the same size take hours to expand. The new hydrogels' rapid expansion is possible because they are riddled with numerous, interconnected pores, each one about the width of a human hair. The pores act as capillaries to draw in water.

"When you swallow something into the stomach, unless it swells very fast, it is going to be emptied into the intestine rather quickly," said Park. "That's why we came up with the so-called superporous hydrogels for gastric-retention applications."

Formulation scientists at Kos Pharmaceuticals were impressed with the technology, said Daniel M. Bell, the company's president and chief executive officer.

"We believe it will extend the number of opportunities we can pursue in improving the formulations of certain existing products," Bell said.

Kos Pharmaceuticals has begun work to develop formulations that can be tested in humans. However, the company will not disclose specific product applications until clinical trials are underway.

The hydrogels are made from various types of polymers called acrylic polymers. But the nature of the polymer is far less important than the gels' porous structure. The pores are formed by using an effervescing agent that fizzes, producing bubbles as the polymer is being synthesized into hydrogels. The bubbles create the pore formation.

Park has been working on the material for 15 years. It has also been licensed to a medical device company called MicroVention Inc., of Aliso Viejo, Calif., for developing a method to treat aneurysms, Park said.

The promise of Park's hydrogels illustrates how the public benefits through university research, said Lisa Kuuttila, assistant vice president and director of the Purdue Office of Technology Commercialization.

Superporous hydrogels have other potential applications, including their possible use in controlling appetite. Because the hydrogels swell so dramatically in the stomach, they might be used to induce the feeling of being full, reducing hunger pangs, Park said.

Another possible use would be to make toys that expand when placed in water, he said. A toy made from conventional hydrogels would take a day or two to fully expand, compared with seconds for the superporous variety.

The U.S. Food and Drug Administration has not yet approved any potential uses for superporous hydrogels.

Sources: Kinam Park, (765) 494-7759,

Lisa Kuuttila, (765) 496-7378,

Writer: Emil Venere, (765) 494-4709,

Other sources: Jennifer Rogers, 305-523-3620,

Research Associate Haesun Park holds before-and-after samples of superporous hydrogels. The material rapidly takes in water through capillary action , resulting in a dramatic swelling. (Purdue News Service Photo by David Umberger)

A publication-quality photograph is available at the News Service Web site and at the ftp site. Photo ID: Park.hydrogels

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