The futuristic idea that microchips could be implanted under a patient's skin to control the release of drugs has taken another step forward.

U.S. scientists have been testing just such a device on women with the bone-wasting disease osteoporosis.

The chip was inserted in their waist and activated by remote control.

A clinical trial, reported in Science Translational Medicine, showed the chip could administer the correct doses and that there were no side effects, according to BBC reports Thursday.

The innovation has also been discussed here at the annual meeting of the American Association for the Advancement of Science (AAAS).

One of the designers, Prof. Robert Langer from the Massachusetts Institute of Technology (MIT), claimed the programmable nature of the device opened up fascinating new avenues for medicine.

"You could literally have a pharmacy on a chip," he said. "This study used the device for the treatment of osteoporosis. However, there are many other applications where this type of microchip approach could improve treatment outcomes for patients, such as multiple sclerosis, vaccine delivery, for cancer treatment and for pain management."

The work is described as the first in-human testing of a wirelessly controlled drug delivery microchip. The technology at its core has been in development for more than 15 years.

It sees the fingernail-sized chip connected to an array of tiny, individually sealed wells of a drug product - in this case, a parathyroid hormone, teriparatide, which is used to counter bone density loss. Fully packaged, the device is about the size of a heart pacemaker.

"The whole device is approximately 3cm by 5cm, and 1cm thick," explained co-author Dr Robert Farra.

"Like other medical implants, it's made out of biocompatible materials. It has a housing with the electronics on the inside, together with the microchips that contain the discrete doses of the hormone."

The drug wells are capped by a thin membrane of platinum and titanium. A dose can only get out when a well membrane is broken, which is achieved through the application of a small electrical current.

The device was tested on seven women between ages of 65 and 70 from Denmark. In their paper, the scientists report that the implant delivered the drug teriparatide just as effectively as the injections pens that often used to administer such treatment, and that there were indications of improved bone formation (although drug efficacy was not formally assessed in the trial). Critically, no side effects were noticed.
The innovation started out as a research project in MIT but is now being developed by a spin-off company, Microchips Inc.
The firm is trying to scale up the system so that more doses can be included. In the trial, only 20 wells were present. Microchips Inc believes drug delivery devices containing hundreds of wells are possible.
However, the team acknowledges that a marketable product is still at least five years away.
Commenting on the research, John Watson, a professor of bioengineering at the University of California, San Diego, listed areas where improvements would be needed.
"In the study, the device failed in one patient (an 8th patient, not included in their analysis), and the manufacturing process yielded only one device with all 20 reservoirs of drug," he said.