VANCOUVER: A microchip inserted under the skin has been shown for the first time to successfully deliver a bone-loss drug to a small sample of women, according to US-led research published Thursday.

The device may someday allow patients to avoid daily injections of medication and permit doctors to adjust their doses from afar, said the study which appears in the journal Science Translational Medicine.

The technology "gives physicians a real-time connection to their patient's health, and patients are freed from the daily reminder, or burden, of disease," said co-author Robert Langer, a professor of cancer research at the Massachusetts Institute of Technology.

Langer and colleagues were to present their findings later Thursday at the annual meeting of the American Association for the Advancement of Science in Vancouver, Canada.

The device is about the size of a pacemaker and contains daily doses of medication inside small wells that open up either on a predetermined schedule, or when the chip is given a wireless signal to release the drugs.

"Each of these wells is covered by a nano-thin layer of gold which protects the drug for years if needed and prevents it from being released," said Langer in a statement released ahead of the presentation.

The wireless signal causes the gold to dissolve and allows the drug to enter the bloodstream.

In this case, researchers tested the device on seven women age 65-70 in Denmark who were prescribed the drug teriparatide for osteoporosis. The microchip was implanted just below their waistlines.

After tracking the women for 12 months, researchers found that the treatment improved bone formation and reduced the risk of bone fracture, and delivered the drug just as effectively as daily injections.

However, the same issues that raised concerns in animal studies were also observed in the women: the formation of fibrous collagen-based tissue around the microchip.

The presence of the tissue has raised concerns among researchers over its potential to interrupt drug delivery, though no such problems were observed in the one-year study, after which the women had the chips removed.

Scientists plan to continue studies on the microchip delivery system in heart disease, multiple sclerosis, cancer and chronic pain. The device is likely about five years away from potential market approval, the authors said.