Microchips run our cars, our washing machines, and even our coffee machines. Soon, they might also dispense medicine. The first study of this approach in people shows that microchips implanted under the skin deliver regular doses of a drug to fight osteoporosis, the bone-weakening condition common in the elderly. Ultimately, this technology may help treat a variety of diseases, including multiple sclerosis and cancer.
Automated drug-delivery devices are already widespread. Insulin pumps that release doses automatically have spared many diabetics from the painful and onerous routine of daily insulin shots. But osteoporosis patients taking the bone-boosting drug teriparatide, a version of parathyroid hormone, still must inject themselves every day. Even former soldiers balk, says Robert Adler, chief of endocrinology at the McGuire Veterans Affairs Medical Center in Richmond, Virginia, who wasn't involved in the study. "You have people who have been in foxholes getting shot at and you wave a needle at them, and they run the other way," he says. So even though teriparatide is the only drug on the market that builds bone, "its use is limited by the inconvenience of administration," says E. Michael Lewiecki, an osteoporosis researcher at the University of New Mexico School of Medicine in Albuquerque, who also wasn't a part of the study.
A team that included biomedical engineer Robert Langer of the Massachusetts Institute of Technology and colleagues from MicroCHIPS, a company based in Waltham, Massachusetts, had a possible solution: a microchip that releases a set amount of the drug after receiving a radiofrequency signal from a computer. Tucking two of these chips and the electronics to operate them into a protective case created a device about the size of a computer flash drive. The team slipped the devices just beneath the abdominal skin in seven elderly women who had osteoporosis. The procedure requires only a local anesthetic, and none of the recipients reported that the implant was bothersome, Langer says. "They didn't even realize it's there."
For 20 days, the researchers prompted the chips to release doses of teriparatide and took blood samples to gauge the effects. Compared with injections, the devices produced slightly smaller but less variable pulses of the drug in the bloodstream, the researchers report online today in Science Translational Medicine. The doses seemed to work. The patients showed higher blood levels of P1NP, a molecule that indicates bone construction. And they displayed no signs of kidney damage, a possible side effect of the drug. Langer says the results show that "for the first time in human beings, you ... can do remote-control drug delivery over a long period of time."
"We have to consider this exciting but preliminary data," Adler says. Lewiecki is also cautiously upbeat. Both researchers agree that the developers need to show that the devices work over a longer period of time and can carry enough of the drug so they need to be replaced infrequently. Researchers are investigating other alternatives for delivering the drug, such as patches users can apply to their skin, Lewiecki says. So whether patients will opt for implanted devices will probably depend on how small they are and how often they need to be changed, he says.
Langer says the company is working on chips that could hold as many as 400 doses, so the implants could work for a year without needing to be replaced. Similar chips might be able to supply drugs for cancer treatment or release painkillers. Future devices could also be interactive, sending updates on patients' condition to their doctors, who could then tweak the dosage. "We have entered the Star Trek era," Langer says.