Figure 1.

Physical modes of GI-based drug delivery. Ultrasound (left) is a technology recently explored for its ability to enable localized drug delivery in the GI tract. The mechanism of action is transient cavitation, whereby small voids in solution collapse as a result of large pressure gradients, sending microjets of medicated solution into the tissue (inset). This technology could be used at home by patients for more convenient administration. Microneedles (right) have also been explored. Initially, a capsule would be coated to aid ingestion. When the capsule reaches the appropriate location (depending on the drug to be delivered), the coating dissolves, revealing the needles, which can then inject the medication directly into the tissue.