Researchers at Children's Hospital in Boston think that they may have created the most reliable means yet of delivering drugs that cannot be taken orally. Their solution is to combine  nanotechnology and magnetism to create a delivery system that is simple, but extremely durable and accurate.

Diabetes and other medical conditions often require long-term treatment with drugs that cannot be taken orally and must be administered on an as-needed basis. The problem with current long-term drug delivery systems is their lack of total reliability when it comes to delivering consistent doses and bearing up under repeated on-off demands.

The Boston researchers' solution is a small implantable device, less than a half inch in diameter, that is placed in a patient's body. The device contains a drug-filled membrane that is also embedded with nanoparticles of magnetite, a naturally magnetic mineral. The nanoparticles are about 1/100,000^th the width of a human hair.

When an external magnetic field switches on near the device, the nanoparticles heat up. Gels in the membrane become warm from the heat and temporarily collapse, opening pores that allow the drug to pass into the body. When the magnetic field is turned off, the nanoparticles cool and the membrane gels re-expand, blocking further entry of the drug into the patient's system. 

One great advantage of the system, says the researchers, is that it doesn't require electronic circuitry or mechanisms that can be damaged or rendered inaccurate by bodily processes. The nanoparticles, which are basically simple on-off switches, do all of the mechanical work and are affected only by magnetism. Because the membranes that hold the medications and nanoparticles do not respond to body heat, fevers and inflammation cannot cause them to deliver drugs inadvertently. Only the heat created by the magnetite nanoparticles when they are "on," which is much higher than body temperature, can make the membrane respond.

The amount of the drug that a patient receives can be controlled by how long the magnetic field is applied. Longer pulses produce higher doses. Theoretically, diabetes patients using such a system would be able to self-administer insulin simply by passing a magnetic field near their implanted drug delivery devices for a set amount of time.

Tests of the new technology thus far have been on animal subjects. The use of nanotechnology and magnetism in human subjects may still be years away. But the Boston experiment shows how the application of simple physics may provide a reliable, simple, even empowering, way for patients with special drug needs to dose themselves. 

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