Microchips as implantable drug delivery devices

A microchip has been designed for use as an implantable drug delivery device. Each dosage of drug is contained in an individually addressable microreservoir. This device has no moving parts, but instead relies on an electrochemical reaction to remove the gold cap off of a reservoir. After the cap is removed, the active substance inside the well is free to dissolve or diffuse into the surrounding solution. The performance of the device in phosphate buffered saline and calf serum has been evaluated using the release of fluorescent dye. The electrochemical and release kinetics are slower in serum than in saline, but pulsatile release was achieved in both media.