Drug delivery to the colon

The recent patent literature concerning drug delivery to the colon is reviewed. A variety of products are under development using either specialised drug coatings or specific devices that target drugs to the colon. The use of coatings that break down in response to microbial flora, change in pH or the permeation of water, herald promise. A number of devices that release drugs in response to changes in pressure, the passage of time or that have degradable tablet cores are also described. However, many of these devices are so complex that they may be uneconomic to manufacture. Colonic drug delivery devices that release drugs in response to microbial degradation are the most propitious, as they are simple and are less susceptible to inter-patient variability.