MICROCHIP IS A NEW MEANS OF MEDICATING

It can be swallowed, injected, inhaled, or delivered to the bloodstream through a time release implant.  Now scientists say they have devised a new way to give patients their medicine: through a fingertip size microchip embedded in the body that can control remotely via a wireless connection.

The drug chip, more than a dozen years in the making, was used to deliver bone-strengthening hormones to women with advanced osteoporosis who otherwise would have needed daily injections.  After four months, the chips were safely removed from the patients’ bodies, scientists reported at a meeting in Vancouver, British Columbia, for the American Association for the Advancement of Science.

Like pacemakers, defibrillators and other implantable electronic devices, the chips are controlled by radio waves in a dedicated medical frequency band.  But instead of delivering an electronic signal to the body, they deliver a chemical signal.

The technology could be ideal for treating conditions that require regular pulses of medication, including pain, infertility, multiple sclerosis and perhaps even diabetes.

In addition to eliminating the need for needles, the chips would make it much easier for patients to comply with complicated drug regimens, doctors said.

Robert Langner, a professor of chemical engineering at the Massachusetts institute of Technology and senior author of the study, which was also recently published by the Journal Science Translational Medicine, and MIT colleagues first presented the idea for a drug delivery microchip in a 1999 article in the journal Nature.  At the time, they envisioned a device that could hold small doses of potent medications in tiny compartments, each sealed by a thin metal membrane.

By applying an electric charge to the membrane, it would dissolve and release the contents of the reservoir.

The researchers started a company, MicroChips Inc of Waltham, Mass, to turn their concept into a product.  Their first focus for drug delivery was women with osteoporosis because human parathyroid hormone, which is used to stimulate bone formation, is delivered in doses small enough to fit on the chips and must be administered in daily pulses.

The scientists encountered a host of technological hurdles along the way, said lead author Robert Farra, president and chief operating officer of MicroChips.  Major challenges included figuring out how to seal the compartments tightly and how to open the chambers at the appropriate time, he said.

Eventually, the team produced a device measuring approximately 1 by 2 inches.  Inside are two microchips, each containing 10 chambers with doses of human parathyroid hormone.

They implanted the devices in eight women in Denmark, positioning the chips beneath the skin near the waistline and programming them to release daily doses of the hormone.  One of the devices didn’t release the drug and the woman was dropped from the study.  In the rest, the treatment was shown to be safe.

One concern was that the fibrous coating that typically grows around implanted devices would block the drug and prevent it from working.

But the microchip-released doses behaved similarly to standard injected doses, and blood tests showed that the bone formation increased.

Patients reported that they were not bothered by the devices once  they were implanted.

The medicine itself was delivered painlessly.

As many as 70 percent of patients who are prescribed hormone therapy for osteoporosis don’t comply with the dosing directions, which involve daily injections for up to two years, experts say.

“The major advantage of the chip is that the patient takes every dose that is prescribed,” said Dr. Robert Neer, a study coauthor and director of the Massachusetts General Hospital Bone Density Center in Boston.  “The chip is more reliable than the patient.”

Matk Saltzman, a biomedical engineering professor at Yale University who was not involved in this research, said the advance solved an intractable problem in implantable drug delivery: how to administer medications in pulses rather than at a constant rate.  Some medications, including the hormone the osteoporosis patients were taking, aren’t effective unless they’re given in discrete doses, he said.

Eventually, drug dispensing chips could be used to deliver any drug—or combination of drugs—that is potent enough to be administered in the tiny doses the device can store, Langner said.

The microchips wouldn’t have the capacity to store the amount of insulin that patients with diabetes must inject each day to regulate their blood sugar.   But the chips could be built with glucose sensors that would notice when a patient’s blood sugar plunged too low and respond by triggering a release of glucagons, a hormone that raises blood sugar levels.

Microchips could theoretically be used to deliver a wide array of medicines, but they would be practical only for drugs that treat serious illnesses, Langner said.