^A little info and update on my personal experience might also back up my hunches that I mentioned in my previous post...
I've been taking buprenorphine as Subutex for about 40 days. I started at 16 mg per day, and began a tapering scheme a week ago, and am now down to about 10 mg per day.
I have mainly taken it sublingually, dosing numerous times per day for the first 35 days or so, but only once for the remaining days. The days of multiple ingestions, have provided me with experience of administering variable amounts of Subutex. On three occassions I used a rectal ROA, twice nasal, and the rest have been sublingual.
My observations so far are as follows:
A) Sublingually, numerous smaller doses spread out over a period of a few hours, are cummulatively more effective than a single large-dose administration. Thus, I assume that with this ROA, the smaller the dose, the higher the chances are of absorbing as much buprenorphine as possible.
B) Rectal administration should probably only be done at doses smaller than or equal to 2 mg buprenorphine. With larger amounts, more water is required for complete dissolution of the buprenorphine, which calls for the use of a larger syringe... this does not go well with an untrained asshole. However, absorption seems to be quite high, and one does avoid the annoyances of sublingual administration (e.g. bad taste, prolonged absorption times when salivary glands produce little saliva, and the large amount of wasted product when salivary glands go amok).
C) Nasal administration is uncomfortable when large amounts of Subutex is snorted. I puked immediately after taking my first line ever. I attempted to snort 1 mg of buprenorphine on the first day of heroin withdrawals, and ended up projectile vomiting immediately. However, I followed up on it, with another 1 mg line (this time with slower, and more controlled inhalation), which went down fine. Even with 1 mg, it seemed like a lot went to waste by dripping down my throat. But I think that some of it must get absorbed when passing the pharynx and esophagus, as long as swallowing is avoided for as long as possible. At the time, however, effects were minimal due to my intense heroin withdrawal symptoms, and the low dose taken. But this method seems popular and effective, and I am going to experiment more, once I reach a much lower daily dose.
My conclusions:
My preferred ROA so far is sublingual. For sublingual and nasal ROA, the lower the dose, the better the absorption rates. This also leads to a better cumulative effect, if small doses are taken in intervals over a period of time. With smaller doses, less goes to waste. The large doses require a lot to be absorbed, and this leads to more wastage, due to over/under salivation, lack of accommodation space in the mouth, nasal cavity, pharynx, and esophagus. And lastly, if you wanna go in the back door, do so at doses lower than 2 mg, with 1 ml syringes, unless well acquainted with alternative gear and methods. Rectal administration has almost no 'spillage' and absorption rates are likely relatively high in the rectum. Absorption percentages are probably also higher at lower doses with rectal ROA.