Medicine may heal, but sometimes taking it hurts. Or causes unpleasant side effects. Or just plain tastes terrible.
This is not a minor concern -- especially if you're a patient who has to take several pills a day, or a child who needs daily insulin injections, or a patient who suffers so badly from fear of needles that you haven't visited a dentist or a doctor for years.
A tiny patch (top) is backed by silicone micro-needles (above, in an enlarged view) that deliver drugs through the skin. The micro-needles are too small to see unaided -- or feel when they pierce the skin.
(Georgia Institute Of Technology)
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Many patients who find the means of taking medicine -- what scientists call "the delivery system" -- too painful or off-putting skip doses, or give up taking their medication altogether.
The dream of solving that problem has inventors toying with everything from skin patches to microchips as possible ways to take drugs for, say, pain, heart disease, diabetes or cancer. More than 100 U.S. pharmaceutical and biotech companies have joined the race, according to Elisa Perez, a market research analyst for Frost and Sullivan, a San Antonio-based health care consulting company. It's no secret why. "Total revenues [for new and emerging methods] are anticipated to reach $42 billion in 2007," Perez said.
The research shares another common goal: getting around the needle -- meaning, the hypodermic needle. That, it turns out, isn't so easily accomplished.
The needle is quite good at its task: getting a medication directly into the tissues and the bloodstream. The trick is first getting through the skin, the body's largest organ and a formidable barrier. "The very outer layer, which is incredibly thin, called stratum corneum, is nonpermeable to most anything," said Mark Prausnitz, an associate professor of chemical and biomedical engineering at the Georgia Institute of Technology. But when you need to deliver drugs, he said, "you want to overcome that."
In addition, injecting a drug lets it escape most of the enzymes, acids and digestive juices in the stomach and small intestines that can render many drugs powerless.
The problem, of course, is that many people fear needles -- so much so that significant numbers of patients (researchers estimate between 7 and 22 percent of the general population has varying degrees of needle phobia) choose to skip treatments and medical procedures requiring them.
New products already on the market include patches, nasal sprays and other devices. More are in development. Following is a look at what is coming down the road, possibly in your lifetime:
Micro-needles
Developed by Prausnitz and his colleagues (and several other companies), the micro-needle is a needle mounted on a patch, about the size of a postage stamp, which is then applied to the skin. Prausnitz expects the technology, when perfected, to be able to deliver some drugs now taken by mouth -- drugs that control high blood pressure, cholesterol and pain.
The needle is as sharp and penetrating as ever, but so small (less than a millimeter in length) and thin it barely stimulates nerve endings. Some patches are designed with multiple needles on board -- sometimes hundreds of them. Not only can't micro-needles be felt; they also can't be seen. "Don't underestimate the importance of the visual cues," said Prausnitz.
Inspired by advances in the microelectronics industry, Prausnitz and his colleagues at Georgia Tech began work on the micro-needle in the late 1990s. If miniaturization could help computers, Prausnitz reasoned, it could aid drug delivery as well. The end result: a micro-needle as long as one or two human hairs are wide -- or, as Prausnitz puts it, "just at the very edge of what you could see."
Micro-needles can work in different ways. In one application, the needles are used to inject medications into the skin over the course of several hours. The needles can also be covered with a drug coating that comes off when the needles are removed. Prausnitz calls the method the "coat-and-poke."
A third way of using the micro-needle -- the so-called "poke and flow" -- involves inserting the needles into the skin on the base of a patch. Drugs can then either be allowed to slowly seep, or diffuse, into the skin through the hollow needles in a passive patch, or they can be given a push from an active patch equipped with, say, a micro-pump.
