This Tiny Submarine Cruises Inside A Stomach To Deliver Drugs

Jan 29, 2017
Originally published on March 20, 2017 11:00 am

A tiny self-propelled drug-delivery device might someday make taking antibiotics safer and more efficient. Think of it as a tiny submarine scooting around inside your stomach, fueled by the acid there.

Oral antibiotics are commonly prescribed life-saving drugs. Once an antibiotic is swallowed, it takes a trip to the stomach, where there's lots of acid. That stomach acid can break chemical bonds in the antibiotic and deactivate it.

To keep that from happening, doctors often prescribe acid-reducing medications like Prilosec or Prevacid. But they can cause side effects such as headache, diarrhea and fatigue.

So scientists at the University of California, San Diego, came up with a device designed to both reduce stomach acid and deliver medication without the side effects.

The swallowable device reacts with stomach acid release of tiny hydrogen bubbles. The bubbles scoot it around the stomach, and a magnesium core reduces acidity as it goes. The tiny device is covered by a special polymer, like a jacket, that is sensitive to changes in the acidity. Once the acid in the stomach is neutralized, the polymer dissolves and the submarines unload their antibiotic payload.

The micro submarine is only 20 microns across, about one-fifth the width of a human hair.

It might sound like an episode of The Magic School Bus, the cartoon series that miniaturized children so they could explore inside the body, but the authors think it could be a big improvement in drug delivery.

The study was led by Joseph Wang, the chair of nanoengineering at the University of California, San Diego. He says that the way that the scooting submarine delivers the drug actually helps the drug work better. "This active movement of the carrier improved the therapeutic efficiency in addition to the neutralization of the stomach [acid)."

The device isn't ready for use in humans yet, but preliminary testing in mice shows that it's safe and effective, at least there. The study was published Jan. 20 in Angewandte Chemie International Edition.

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OK, this next story was listed on the rundown for our show this morning with the headline Stomach Submarines - definitely grabbed my attention. So these are devices that can make oral medications more effective. And they're just like you might imagine from the name. They act like tiny submarines, diving through the stomach, neutralizing stomach acid and delivering drugs. Researchers say they could be especially important for antibiotic treatments. Here's NPR's Madeline Sofia.

MADELINE SOFIA, BYLINE: Oral antibiotics can be very useful medications - But there's a problem.


SOFIA: The gurgling acid in your stomach can destroy some antibiotics. In those cases, patients have to take an acid-reducing drug before each dose. Unfortunately, those extra drugs can come with side effects, such as headache, diarrhea and fatigue. Liangfang Zhang was looking for a way around that problem.

LIANGFANG ZHANG: The mission is to deliver the drug without taking some extra drug to neutralize this acid.

SOFIA: Zhang is a professor at the department of nano-engineering at the University of California, San Diego. The solution was a tiny, self-propelled device.

ZHANG: It looks like a mini submarine.

SOFIA: And that mini submarine is loaded up with antibiotic cargo. The clever device actually turns a problematic acid into its own fuel. As the submarine neutralizes the acid, it generates tiny hydrogen bubbles. Those bubbles propel the sub through the stomach, spreading the antibiotic. This is especially helpful in targeting ulcer-causing bacteria that hide out behind a layer of stomach mucus. Normal antibiotics don't actively penetrate that layer, but the submarine does.

ZHANG: Because it's powered and they can penetrate into the tissue.

ZHANG: Once the sub senses it's in the right spot, the antibiotic cargo is unloaded. The drug sub isn't ready for testing in humans yet, but it has been shown to be safe and effective in mice.

Madeline Sofia, NPR News.

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