I have never done this, however, as a general rule of thumb, it’s safe to assume that anything administered rectally will have a more intense and/or immediate bioavailability. This is because it bypasses the digestive tract and goes directly to your bloodstream, skipping every step in the metabolic process.
This the same reason insufflation, smoking, and injecting are typically much stronger RoAs than oral consumption.
If you intend to do this, my suggestion is to start as small as possible to get a feel for the effect. 4 shots of vodka might get you mildly tipsy when drank, but 4 shots in a rectal tampon can kill you.
When you ingest too much of something orally, your body’s reaction is to throw up any excess. When you boof something, it’s in there. It’s in your bloodstream in an instant. There’s no removing it.
Small bites at a time for this sort of thing. Smaller than you think.
You can always do more, but you can never do less.