Planar bioadhesive microdevices: a new technology for oral drug delivery.

The oral route is the most convenient and least expensive route of drug administration. Yet, it is accompanied by many physiological barriers to drug uptake including low stomach pH, intestinal enzymes and transporters, mucosal barriers, and high intestinal fluid shear. While many drug delivery systems have been developed for oral drug administration, the physiological components of the gastro intestinal tract remain formidable barriers to drug uptake. Recently, microfabrication techniques have been applied to create micron-scale devices for oral drug delivery with a high degree of control over microdevice size, shape, chemical composition, drug release profile, and targeting ability. With precise control over device properties, microdevices can be fabricated with characteristics that provide increased adhesion for prolonged drug exposure, unidirectional release which serves to avoid luminal drug loss and enhance drug permeation, and protection of a drug payload from the harsh environment of the intestinal tract. Here we review the recent developments in microdevice technology and discuss the potential of these devices to overcome unsolved challenges in oral drug delivery.