scientificamerican.com
Chipping away at drug delivery: With a tiny implanted chip, filled with individual doses of medication, a patient might soon be able to forget all about daily shots—and perhaps even pills. Image: MicroCHIPS, Inc., Massachusetts
For people who face frequent needle jabs to treat chronic conditions, a new technology is on the horizon that might make treatment a lot less painful.
Researchers report that a new wirelessly controlled microchip, implanted under the skin, can safely and reliably give osteoporosis patients the daily dose of a drug that they need for at least 20 days in a row. The findings were presented at the American Association for the Advancement of Science annual meeting in Vancouver and published online Thursday in Science Translational Medicine.
Some 55,000 people in the U.S. with osteoporosis face daily injections of a bone-boosting hormone (known as human parathyroid hormone fragment, which is the basis for the drug teriparatide, sold as Forteo). But during a two-year daily regimen of the shots, close to three quarters of osteoporosis patients fail to take the drug as often as they are supposed to. High noncompliance makes this condition an especially compelling target for an automatic drug-dosing system.
“In a silent disease like osteoporosis, [patients] don’t feel any difference, and they just give up the injections all together,” says Robert Farra, co-author of the study and chief operating officer at MicroCHIPS, the company that makes the chip. Doctors can either preprogram the new device for a release schedule or send release instructions directly to it via a dedicated radio frequency.
For the study, eight postmenopausal women with osteoporosis had the chip—which is about three by five centimeters and can be implanted during an office visit—inserted under the skin around their bellies for about three and a half months. Daily doses of teriparatide were preprogrammed to release for about 20 days during the middle of the trial. Seven of the eight received most of their doses right on schedule, and each of these said they would opt in for another chip—most reported that they had forgotten that it was there.
Microchips like these could also be used for other conditions that demand discrete drug dosing, such as multiple sclerosis, for which some patients must inject a dose of interferon once every two days. Therapies that use hormones are particularly appealing for adaptation to microchip delivery because the body usually releases hormones intermittently—just as the chip does, Farra says. In the future, a device like this might also be able to help diabetics both monitor and treat their condition.
This sort of direct communication in an implanted device could help patients stick to medication regimes without having to face a syringe or pill bottle.
Remote controlled
The device can be preprogrammed or controlled wirelessly via the Medical Implant Communication Services (MICS) band, set aside for the U.S. Food and Drug Administration (FDA) by the Federal Communications Commission. And the device can also report back dose-delivery data to a computer-based system.
Scientists demonstrated that this sort of wirelessly controlled drug delivery might be possible in 1999. Some major technological hurdles needed to be cleared in the interim, Farra says.
The first challenge was figuring out how to create seals on the drug-holding wells that would stand up to moisture inside the body. Researchers solved this by using compression welding to create a hermetic seal around the well’s metallic membrane. The second hurdle was figuring out how best to open those tight seals. The scientists settled on an electrical current that would melt the membrane on command. The final hurdle involved scaling things down—getting all the components and wells onto a chip that would fit comfortably under the skin.
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