Rectal administration (plugging) involves inserting the dose through the anus, where it is absorbed via the epidermal tissue of the rectum. This method of administration has some of the same advantages of sublingual administration, such as the denial of first pass metabolism.
Some debate exists about how effective rectal administration is. It is often touted to have rapid onset and more pronounced effects with minimal shortening of the duration. At the same time, some people have found rectal administration to be ineffective. Although this may be true, it most likely results from improper technique as opposed to the ineffectiveness of the method.
The unpleasant burning sensation sometimes experienced with rectal administration is usually a result of insufficiently deep insertion. The dose should be pushed in so that it is two knuckles deep.
Another complication that can be encountered is the presence of feces in the rectum. You don’t necessarily have to give yourself an enema, but evacuating your bowels prior to inserting the dose is a good idea.