This occurs when a substance passes from the fluid in the tubular lumen through the apical membrane, across the cytosol , and then into the interstitial fluid.
Yes, it's potent stuff. Cat receive it either as an injection or orally. It takes effect in roughly half an hour, lasting about 8 hours before another administration is necessary. Cats usually react negatively to opiates, but buprenorphine is an exception. That's one reason vets use it if they can receive the necessary special certification.
Hi there: I am on and of Buprenorphine 8mg for about 2 years now (to stay awake during the day 1 pill cut in 4 quarters (2mg) during the day). In order to not get into withdrawl you need to tape it down. Meaning you take every day a quarter of the pill less. I have done this 4 times now and it really works.