United Press International - October 19, 2003
Steve Mitchell, Medical Correspondent

The chip -- about the length and thickness of a fingernail -- could be useful for delivering drugs that must be taken continuously, such as pain relievers or antidepressants, and has the potential to change how the pharmaceutical industry approaches drug delivery, a $54 billion market in the United States.

Robert Langer, a biomedical engineer at the Massachusetts Institute of Technology and principal investigator of the study, called the device "a pharmacy in a chip" and said the ability to load multiple drugs on a chip makes it an attractive method for delivering medications to patients who have to take several per day, such as the elderly or AIDS patients.

The chip, comprised of polymers that are completely absorbed by the body, also is "the first completely degradable system" for drug delivery and does not require a power source or outside stimulus to release the drugs, Langer told United Press International.

He said he anticipates the polymer chip will change drug delivery strategies because "it offers opportunities you could never do before."

Nicholas Peppas, chair of chemical and biomedical engineering and pharmaceutics at the University of Texas at Austin, said the chip is "a tremendous innovation" and represents "really, a very exciting application."

This could be used as a "new system that the patient can take once over a period of two to three months and forget about it," Peppas told UPI.

It would be useful for ensuring patients take their entire course of medications for diseases or conditions where it is essential, such as tuberculosis or birth control pills, he added.

The chip offers an advantage over currently available time-release capsules or patches because those release the drug continuously until the supply is exhausted, Peppas said. The microchip allows for delivering precise doses of a drug at specifically determined intervals.

Even more exciting is the chip completely breaks down into innocuous materials that will be cleared out of the body, he said.

The chips are "relatively expensive, so the cost will have to come down before they can be competitive to classical pharmaceutical applications," Peppas said, but it offers "lots of promise."

A major problem with previous attempts at implantable drug delivery systems is that they released a large amount of the drug at once, which can cause serious side effects.

Prior attempts using degradable polymers also encountered technical problems. Earlier versions mixed the polymer directly with the drug but this meant small alterations in the composition of the polymer or amount of drug in the blend could significantly affect how much drug was released.

Other attempts used silicon, which does not break down in the body and eventually must be removed, and also required a power source.

Langer's team overcame those technical barriers by using two types of biodegradable polymers to create their chip, they reported in the November issue of Nature Materials. A chip prototype contains approximately 36 individual reservoirs, which can be filled with precise doses of different drugs and then capped with polymers to seal them. As the polymer cap degrades, an exact amount of drug is released.

The release time for each reservoir can be adjusted by changing the composition or thickness of each cap so it deteriorates at a certain rate, releasing different drugs at different times without the need for an outside power source to stimulate release.

Langer's team ran tests in saline solution with prototype chips loaded with human growth hormone and a blood-thinning drug called heparin. As the various polymer caps degraded, doses of the drugs were released at several different times, ranging from the first day to more than four months later.

The researchers also conducted preliminary tests in animals and found the chips seem to work just as well inside a live body.

Langer noted the polymers used in the chip are approved by the Food and Drug Administration and used in sutures and other medical devices, which could speed up the time it takes to get the chips approved for use in humans.

Microchips, a Bedford, Mass., company focused on drug delivery products, owns the rights to the technology used in the chip and said it expects the appearance of the study in the prominent science journal Nature Materials will generate a flurry of interest from pharmaceutical companies.

Pharmaceutical and medical device companies have expressed strong interest in implantable drug delivery systems, such as the chip used in the study, and this is "really where the industry is headed," Microchips President and Chief Scientific Officer John Santini told UPI.

"The primary reason is the precise control over timing and delivery of a drug" the implantable systems offer, Santini said.

Microchips is in the process of identifying applications appropriate for the chip, but one candidate is vaccine boosters, he said. Multiple doses of a vaccine could be loaded on the chip and scheduled to be released at different time intervals. This could be useful for patients who are in remote locations and cannot easily return to medical clinics for follow-up vaccine booster shots.

Another application is using the chip for oral delivery of drugs to avoid upsetting the stomach. It could be possible to "target delivery so that the drug reservoirs open up in specific places in the gastrointestinal tract" after it passes through the stomach, Santini said.

In addition to avoiding problems in the stomach, this potentially could make drug delivery more efficient, he added.

Joyce Wong, assistant professor in biomedical engineering at Boston University, agreed pharmaceutical companies and drug delivery companies likely will move toward something like the chip.

"It's a great idea," Wong told UPI. The unique ability to completely degrade and release drugs at specific times offers several advantages, including local delivery of drugs so the chip could be implanted close to the site where it is needed, such as in the brain to treat brain cancer, she said.

"The key is that it's degrading away," Wong said. "The whole thing will be gone in a matter of weeks or months."

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