From what I know, I believe that most NSAIDS can be absorbed through your lower GI tract. Widly available here is of course Tylenol suppositories, and in Canada they have Naproxin rectal suppositories too. So that makes me believe that most of them can be absorbed via that route.
However, because of the nature of the beast, taking them orally or rectally can produce basically the same neg results, just different ends, just not as severe when taken rectally.
A rule of thumb that I use in nursing for some of my patients is that most all meds can be, and are usually as effective, some even more etfective, at least faster acting, when given rectally. They don't have to be processed they can just be absorbed. You can't do that with medications that are enteric coated, time released, or some of the other "serious" meds that need the above process to work properly. But if my patient is in serious enough condition that I am giving their meds rectally to them, usually all the serious meds are D/C'd and only comfort meds are being given anyway.
Just a side note, Advil is coated, so when I give it rectally I disolve it first, if not, it just sort of sits there and takes forever to work. Hope this helps?
Mashie