Picked up one of these today from a local friend.. for a friend.. paid out the ass for it..
What should I recommend my friend dose this at.. hes been doing 30mg oxy's for a couple days now.. but this is all my dude had available.. Just want to inform my friend of correct dosage before taking too much.. I was thinking an eighth of the pill..
I believe I can be of help. I generally rail about 35 mgs of oxy. Recently, I tried a 10 mg IR opana. I would have to snort 7.5 mgs of one to get high, but I had calculated I would only need 2.5 mgs.
Next, I got my hands on a 40 mg ER opana (generic formula of the old Endos). This time, an eighth or so was plenty. Granted, breaking one pill up this many times gets difficult and you eventually are just ballparking it and kill your tolerance, etc. There is definitely a difference when it comes to the amount of binders you're snorting and the surface area vs. active chemical.
All that to say, an eighth is a good place to start. I wouldn't recommend doing any more at first because it's strong and you don't wanna fuck up. Keep in mind, however, that it is ~90% intranasally bioavailable, while oral is 10%.
Also, this post would do better on /r/opiates.