Micro-needles could make drug regimens more convenient for patients. Instead of having to swallow a fistful of pills each day, the patient could simply slap on a micro-needle patch and get on with life. Clinical trials have shown the technology to be effective, safe and painless for certain drugs. But development remains in the early stages. Prausnitz said you can expect to start seeing micro-needles in your doctor's office in two to five years.
Needle-Less Devices
How do you breach the body's largest protective barrier without a needle? By changing the physical structure of the skin, so that drugs can get through without making a hole.
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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The method in use longest is called iontophoresis, a technology that uses electrical currents to deliver local anesthetics. Devices such as Needle Buster and NumbyStuff apply a low-level current that pushes a topically applied drug through the skin.
Ultrasound -- the same technology used to scan fetuses in the womb -- is another needle-less solution. Physical therapists have found that drugs applied to the skin work better when the skin is then massaged with ultrasound. This finding ultimately led to the design of an ultrasound device created specifically to make the skin more permeable.
The "SonoPrep" was approved by the U.S. Food and Drug Administration in August 2004 to deliver topical anesthetics, used to numb the skin before more invasive procedures, such as inserting an intravenous (IV) tube or doing small biopsies. The device "zaps people" and "creates temporary pores, super-little-tunnels, in the skin" so "stuff can go through," explains Massachusetts Institute of Technology biomedical engineer Robert Langer, who helped develop it. Within 24 hours, he said, the skin returns to normal. A SonoPrep application takes about 15 seconds. The futuristic-looking probe-like device is marketed by Sontra, of Franklin, Mass. In the future, Langer predicts it will be used to deliver pain medications, insulin and some vaccines.
The Patch
You may have seen your friend, who is trying to quit smoking, wearing one. Or your girlfriend, who is taking her birth control hormones via the skin. Or your relative with angina, who's been prescribed a course of nitro-glycerine -- via patch.
The patch debuted in the 1980s, making it a relative old-timer (though not nearly as old as the needle, developed in 1853). Only a few drugs can use the patch as a launching pad to migrate through the skin in their active form. Still, patients like the method, thanks to its ease of use and painlessness, so researchers continue working on improvements.
Two of these improvements, again, focus on changing the skin structure. One comes from an Israeli company named TransPharma. Its ViaDerm patch gives the patient a device similar to a computer mouse. The patient places the device on the skin (usually, of the arm or forearm) and clicks, transmitting an electrical current. The current creates microscopic skin openings over which she then slaps on the patch containing the medications. The meds then have 24 hours to enter before the skin returns to normal.
The PassPort patch, made by Altea, of Tucker, Ga., uses heat to produce a similar effect. "If you warm up the skin very locally -- a microscopic spot," said Prausnitz, "you create a small thermal explosion at that site. That explosion makes a very small crater in the skin, and that crater is a hole in the skin that drugs go through." This may sound scary, but you shouldn't feel a thing. Researchers hope the method could lend itself to delivery of vaccines, genes or proteins to treat conditions such as metabolic disease and heart disease.
The PassPort patch, containing a reservoir of drug, is applied to the skin. A small hand-held medical device -- like a remote control -- activates the patch and delivers a short pulse of energy, "creating tiny channels in the skin surface," according to the manufacturer. The drug or vaccine flows into the body through the microscopic channels. The patient can leave the patch in place for up to a day -- depending on the required dose. When the patch is removed, the microscopic channels close and the skin quickly returns to its normal state.
Altea -- now testing the patch's use for delivery of insulin and certain narcotic painkillers -- plans to seek marketing approval in the United States in 2007, reports chief executive officer Eric Tomlinson.
Breathe It In
Some researchers think the best way to a man's health is through his lungs, not his skin. The lungs are, indeed, a critical entryway into the inner workings of the human body. They are why, for people with asthma, inhalers often work.
For one thing, the interior surface of the lungs offer an enormous working area for drugs to penetrate -- "roughly the size of a tennis court," according to Stephen Farr, senior vice president and chief scientific officer of Aradigm of Hayward, Calif., a maker of inhalers.
The lungs are also a membrane away from a person's bloodstream, or, as Farr puts it, "one cell layer away from the blood capillaries."
Inhaler technology has proved so successful that other medications are now routinely available this way, including insulin and drugs to treat migraines. More than 300 drugs are in late-stage development for this "pulmonary delivery" method, which market analyst Perez projects to be a $9 billion business in the United States five years from now. They include epinephrine, the drug used in response to a severe allergic reaction. Today there is only one way to get this drug in an emergency: a large-bore needle jammed force fully into the meaty part of the thigh.
The Microchip
Granted, this is going to scare all those conspiracy types out there convinced the government has planted microchips in our brains. The reality is that some private companies are speeding toward a technology that implants medicine-carrying chips under the skin, where they slowly and reliably release their payload into the bloodstream.
MIT's Langer and his colleagues have already developed several prototypes, some no bigger than a matchstick. The first one, made of silicone and gold, held more than 400 tiny chambers, each bearing medication. This offers the possibility of repeated doses of one or several medicines. The rate of release can be altered at any time, because the chip is run by remote control. "The way you open a garage door," said Langer, "you can open up a well inside the chip."
ChipRx of Lexington, Ky., and MicroCHIPS of Bedford, Mass. are two biotech companies currently testing the microchip. Marketing "would all be at least two to five years away," according to Langer. Someday, said Langer, he sees the microchip "being swallowable." Patients may be able to get all their medications this way. One chip, one gulp -- instead of dozens of pills a day. "The chip," Langer predicts, "will deliver them when you want to."
So this all means the needle is history, right? You wish. "My expectation is that the hypodermic needle will never disappear," Prausnitz said. Ouch.•
Ranit Mishori, a family practice resident at Georgetown University/Providence Hospital, recently wrote for the Health section about off-site surgical centers.
