Teaching Old Drugs New Tricks

Researchers working to develop new and better methods of delivering medicine

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By
HealthDay Reporter

MONDAY, Jan. 6, 2003 (HealthDayNews) -- Inhaled insulin for diabetics. Nanoparticles that detect the onset of disease before it develops. Implantable microchips that dispense precise amounts of medicine at exactly the right time.

If researchers have their way, swallowing a bitter pill may eventually become a thing of the past.

Across the world, researchers are working on developing new methods of delivering drugs that are both more effective and more pleasant for the patient.

The drug-delivery field is booming. In the last 20 years, drug delivery has gone from a small niche field to a $20 billion industry, according to the American Chemical Society.

You're probably familiar with some of the advances already made: nicotine patches to help smokers kick the habit, and nasal inhalers to treat allergies.

But those are only the beginning, said Robert Langer, a professor of chemical and biomedical engineering at Massachusetts Institute of Technology in Cambridge, Mass.

"The industry has grown tremendously," Langer said. "Better pills. Patches. New types of aerosols. It's really just taken off."

Like with a new drug, new drug-delivery methods have to undergo extensive testing to prove their safety and gain U.S. Food and Drug Administration approval.

Diabetics, for example, have used insulin injections to control their blood sugar for decades. Researchers are currently testing an inhaled form of insulin to do away with dreaded needles.

But before it's approved for market, researchers must prove that inhaling insulin won't cause other problems, such as damage to the lungs.

Here's a rundown of what the American Chemical Society views as some of the most promising new research in drug-delivery technology:

The Problem With Pills: There are two major drawbacks to taking an ordinary medicine orally, Langer said.

The first is that a pill's strength isn't evenly distributed throughout the day -- there can be a peak when it's first digested and a valley when it begins to wear off.

Researchers are working to develop extended-release pills that deliver the medicine at a more steady pace, or that can tailor the dosage to specific times of the day when it's needed most. One of the first available is called Concerta, a once-a-day pill for Attention Deficit Hyperactivity Disorder, Langer said.

The second difficulty with taking medicine orally is that the stomach simply devours many compounds. That's why insulin, for example, has to be injected and not swallowed.

Researchers are working on pills that can survive the stomach and get to the part of the body where the medicine is needed, Langer said.

Your Very Own Pharmacy: Langer and other researchers are working on developing a microchip that could be implanted under the skin and programmed to act like a tiny pharmacy, directing the release of drugs exactly when you need them.

The chip has tiny reservoirs that could hold several types of medicines. The chip could also transmit the information to the doctors office or hospital.

Seeking Out And Destroying Disease -- Before It Starts: Drug-delivery researchers are working on developing nanoparticle sensors -- tiny, atom-sized particles that course through the bloodstream and can detect compounds that may be markers for disease.

Nanosensors might be on the lookout for excess glucose, a sign of the onset of diabetes, or excess cholesterol. The particles could trigger a system (such as a microchip) that would release a drug to fix the chemical imbalance. The nanoparticles are biodegradable and will self-destruct in a few days, Langer said.

Real-Life Star Trek: On the TV show, Bones, the ship's doctor, gave patients medicine by painlessly zapping them with a gadget.

Soon, that may be more than science fiction.

Researchers have discovered that placing an ultrasound on the skin for about 15 seconds temporarily disorders the fatty substances in the skin, making it more permeable. This allows larger molecules to pass through and enter the blood stream.

The aim is to one day use ultrasound to deliver medicine -- insulin, perhaps, or anesthesia directly on the source of pain.

Ultrasound could also help non-invasively gain information about what's going on in the body. One day, diabetics might be able to zap their skin with an ultrasound in the morning, place a sensor over the location and track their blood sugar. The current method is pricking the skin and extracting a droplet of blood.

When All Else Fails, Grow a New Organ: Many diseases cannot be treated by drugs, Langer said. The second major area of drug-delivery research is tissue engineering, or growing new cells or new organs in the laboratory.

For example, if a person is dying of liver failure, the only way to treat them is by transplantation. For that, they have to wait for someone else to die, Langer said.

But what if a person could receive new liver cells that would grow and regenerate the damaged organ?

It's not such a far-off hope.

Cells are intelligent, Langer said. Given the right circumstances, they will organize themselves to take over the function of the cells in the area where they are placed.

Langer and his colleagues have developed a polymer support system, similar to a scaffolding, that the cells can use as a guide. The scaffolding gradually degrades, leaving only the living cells.

What To Do

Read more about using ultrasound to deliver medicine at Wired. Read more about tissue engineering at Tissue-Engineering.net.

SOURCES: Robert Langer, Ph.D., professor of chemical and biomedical engineering, Massachusetts Institute of Technology, Cambridge; American Chemical Society

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