Archive for Saturday, December 9, 2000

Smart pills

High-tech drugs release correct dosage at just the right time

December 9, 2000


Okay, be honest just how often have you taken a prescribed medication exactly how and when called for by the label? Chances are, a dose has been missed here, or the timing's been off a few hours there.

So how about a pill that you could remember to take just once a day, that would release not just one drug, but all the medicines you're supposed to take over 24 hours, at just the right time.

Drug designers are moving quickly to put such "smart drugs'' on pharmacy shelves using technologies ranging from a new generation of inhalers and skin patches to complex chemical microspheres and even time-release capsules with programmable microchips.

Soaking it up

Consider the new spheres developed by chemical engineers at Purdue University in West Lafayette, Ind. They're acid resistant to protect medicines from the harsh environment of the stomach, but then become squishy in the less acidic intestinal tract, releasing the drugs where they can be absorbed.

The key ingredient of the microspheres is a chemical compound called polyacrylic acid, which is best known as the "superabsorbent'' filling in diapers. By grafting this material with a plastic polymer, the researchers produced tiny sponges that have a mesh-like structure that expands and contracts in response to changes in acidity.

In diapers and similar products, the polyacrylic acid soaks up large volumes of liquid while keeping the surrounding areas dry. In delivering drugs, the microspheres are loaded with medicine and dried before use.

After being swallowed, the spheres stay collapsed until reaching the small intestine, where the swelling mesh acts like expanding bars of a cage, so that the substances trapped inside can escape and be absorbed easily.

Although other researchers have fabricated microspheres based on similar materials, the Purdue team has led the way with producing them in water, which means they are non-toxic and quick to react once they clear the stomach.

"The best thing to do is to use water for the production of materials intended to deliver medicines, and we have been able to do just that,'' said Petr Bures, a doctoral student in chemical engineering who participated in the project.

"The pressure peaks when these people get out of bed in the morning, so ideally you'd like to deliver a high level of medicine at exactly that time, and our technology could do this."

C. William Rowe, a scientist at Therics pharmaceutical company of Princeton, N.J.

Then there's 3-D drug printing, a process similar to inkjet printing, being brought on line by the Therics pharmaceutical company, of Princeton, N.J., based on technology developed by scientists at the Massachusetts Institute of Technology.

In this process, from 30 to 50 layers of drugs and binders and powders to control their release are assembled on a matrix, to control which portion of a tablet dissolves in what part of the digestive tract.

C. William Rowe, a Therics scientist, talks about a cancer patient being able to take one pill for both chemotherapy and to control the resulting nausea, or dosing regulated for the time of day, such as medicines for high blood pressure.

"The pressure peaks when these people get out of bed in the morning, so ideally you'd like to deliver a high level of medicine at exactly that time, and our technology could do this,'' Rowe said.

New delivery systems

At the same time, various biotech companies are producing systems to deliver drugs through the nose, the eyes, the lungs, and through the skin using injections, implants and even sound waves.

At Advanced Inhalation Research Inc., the lungs have been the target for delivering large therapeutic proteins, such as insulin and hormones, without passing through the obstacle of the gut, which digests proteins.

David Edwards, an engineer with the firm, predicts a future in which the inhaler "will be a very simple thing, the size of a pill'' that's both disposable and breath activated, so that the patient "won't sense anything at all.''

Another line of research involves packaging new drugs in dissolvable layers of fats, or liposomes, which offer the promise of delivering pharmaceuticals to specific organs and tissues that collect specific types of fat. Once in place, the drugs would be able to leak out slowly.

Several anti-fungal drugs delivered this way have either been approved or are in the FDA pipeline, while researchers are also working with them to deliver cancer-fighting agents.

The really exotic remedies are expected to arise from two areas genetic studies and nanotechnology the process of shrinking machines, including computer chips down to molecular size.

Hordes of biotechnology companies are racing to identify and decode the proteins and other chemicals our genes tell us to make each day in order for our bodies to run properly. And just as many researchers are working on miniaturization, including some who believe that information processing using DNA, rather than silicon circuits, will operate computers of tomorrow.

Ultimately, the goal is to create "drugs'' that will instruct the body to heal itself without damaging other systems.

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