I read a study once that found there can be a huge range in bioavailability for rectal hydromorphone for different people. I'm on my phone at the moment so it's hard to search for the source and thus I'm not going to try and pull numbers from my memory, but again in this study there was a big difference between the people who absorbed it best and worst via that route. If I'm remembering that right (I think I am) and it is relatively reflective of the larger population (more of a tossup), there's no real way to know whether rectal hydromorphone will be particularly effective for you or just kind of meh. I'm NOT telling you to IV it instead... Just kind of throwing it out there as an interesting fact.
Anyway it's been a while since I've plugged hydromorphone on its own but I seem to recall it could be a little stubborn getting to the right place. The problem was always that I wouldn't feel it as much as I wanted and I'd add a little more and it wasn't enough and I'd add a little more and it still wasn't enough and I'd add a little more and suddenly it would be too much. So at least for some people, there can be a pretty fine line for what's not so great because you feel nothing and what's not so great because you're sick.
While 40mg of oxycodone is a decent amount, I wouldn't say it's enormous or anything and rectal hydromorphone has the potential to be rather potent. Depending on what you may or may not have already decided to do, I would recommend adding pretty small increments at this point... Even 1mg at a time if you could manage to get a piece that small. I always try and give more conservative advice because I don't want to be responsible for anyone feeling poorly or worse but I am being honest about how quickly the line of comfort was crossed in my own experience. You're also in withdrawals it sounds like so depending on how long that's been it could take slightly less than you're thinking.
Honestly if you had just come on here and had asked how much hydromorphone to take before taking it, I don't think I would have recommended you take as much as you already have, let alone adding to, it based on your stated tolerance. Only you know how you are feeling and how much more you can take, but I think you need to go really slowly from this point on. It's possible you don't absorb it as well rectally as some others might so you may very well come back and say that you took more than I suggested and were totally fine. Without any way to know whether or not you will be though, I always feel it better to err on the safer side of caution.
