Other implantable devices can become bogged down by tissue that grows around them. But the researchers found that even with the extra layer of tissue around it, drug absorption via the chip seemed to work just fine.
The researchers also found that dosing accuracy was actually better than standard injection, says Robert Langer who, with fellow study co-author Michael Cima, both of the Massachusetts Institute of Technology, first started developing the concept of an implantable wireless microchip in the 1990s. And it might not end up being that much more expensive, Farra says.
Farra's group aims to provide the medication-filled chip for a price that will still cost no more, including implant and removal surgery, than the $10,000 to $12,000 that a year's worth of teriparatide injections currently cost. The approach also vastly increases compliance. The current small study did not measure whether or not women with the implant had fewer bone breaks than people who were in charge of their injections. But if future studies find that by increasing compliance patients with the chip also decrease their risk of breaking a bone, then it could also help decrease medical care costs in the long run. With an aging population, the cost of osteoporotic fractures is estimated to top $20 billion by 2015 in the U.S. alone.
External approval for internal dosing
The device still needs perfecting. The eighth patient in the study had a malfunctioning chip that did not release any medication, which might lead some to worry about potential for accidental release of excessive dosages. But with the design of each well's membrane and activation mechanism, Langer says, "I don't think there are big safety concerns."
Other wireless medical devices have raised eyebrows for their potential susceptibility to signal interference or even hacking. Because the device uses the MICS frequency, it is likely to face less interference than if it were on busier parts of the band. Also, a unique ID number is required to establish connection with each individual chip, decreasing the ease of hacking.
Farra and his colleagues have built an implant—the same size as the one in the study—that contains 365 doses, which, they suggest, could provide daily dosing for a year or possibly even every-other-day doses for two years.
Farra suggests that more development and trials could yield a yearlong chip ready for FDA approval in four years.
John Watson, a professor of bioengineering at the University of California, San Diego, thinks this estimate is a tad optimistic. He has been helping to find ways to move technology from the drawing board to clinical use more quickly. But, he says, for a device like this, researchers will need to tweak the technology, recruit more patients, run a one- or two-year-long study and complete another year or two of follow-up—plus time to review the data and seek approval from the FDA. "That's very doable," says Watson, who wrote an editorial about the new device that was also published online Thursday in Science Translational Medicine. It is just a matter of doing it, he says.
If the chip proves successful in larger and longer trials, it might also be adapted for treating more acute conditions, such as delivering drugs for a month or two after a heart attack. The chip could also be filled with a mix of drugs delved out in dosages specifically tailored to a patient's needs, Farra notes. For instance, if a patient is responding well to medication, a doctor could dial back the release frequency. Or if a patient needs to be slowly weaned off or onto a drug, there could be smaller doses preset in the chip.