Wow, I've never even thought to dose that low. My opiate tollerance isn't very high I'd say. I'm feeling pretty good on 30mg hydrocodone + 25mg promethazine right to give you an example. Do you use the orange 8mg suboxone pills with the sword on one side? That's what I have and if so how do you even go about breaking a piece of the pill off that small?
Bio-availability wise, buprenorphine iv = 100% whereas sublingual is around 30%.
I do indeed also have the N8's, with the sword on one side.
The way to break up a N8 into smaller doses is to invest a few dollars ($2 to 5 max) into a pill crusher (you may already have one, then it's free

) and a pill splitter. With a pill splitter (and careful placement), you can get pretty accurate 2mg sections of the pill. Or, if you just want to get the pill crusher, you can do that too, there's just more work ahead (you'll see).
Then, place the 2mg section (or 8mg if you don't have/don't want a pill splitter) into the pill crusher. Twist the top on until the pill is crushed. I also like to tap it around a little, then crush a second and third time to make sure it's as fine as that will get me. Then, I dump the contents out onto a clean mirror. I then use razor blades (or a card like a credit card, ID, etc) to split up doses. If you have a 2mg section, you can split it into 4 piles, each making 0.5mg. This is a nice starting dose for IV bupe, I found the rush most pronounced at 0.5mg (versus higher doses - I too tried IV 2mg, and it didn't give me the high that 0.5mg did. Some people are different, so if you don't get good results out of a low dose, there's no harm in having tried. If it works at a lower dose, then you save a lot of bupe thanks to increased BA).
If you want 0.25mg sections, you can split a 2mg pile of powder into 8 sections, each being around 0.25mg. It can be tricky to separate the powder into seemingly equal piles, but with a little practice it'll get easier.
I would recommend trying 0.5mg and seeing what you think.
Yeah man lol i kinda lost it in that post I was a little pissed off. Its not even about me knowing I mean this kind of question gets asked daily and can be answered by searching the forums or looking at the subutex/suboxune thread. About the low dosage of bupe I felt this too but I though norbupe could not really cross the BBB? this makes sense then since nor is quite a bit stronger.
Norbuprenorphine can't cross the BBB on its own, however I do believe once buprenorphine has crossed the BBB, its metabolites will still be there. When drugs are metabolized, they are metabolized at the site of the neurotransmitter. So, the metabolites are still across the BBB.
Norbuprenorphine not being able to cross the BBB on its own just means that there isn't a "better form of buprenorphine out there". This means that the only way you can experience norbuprenorphine is through buprenorphine (as I don't think any other prodrugs of norbuprenorphine have been discovered ...yet...%)) meaning you can only get it with lower doses of buprenorphine. With higher doses of buprenorphine, the buprenorphine will saturate all mu-opioid receptors, and will prevent its metabolite, norbuprenorphine, from activating receptors.