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.
Medical professional advise tapering off Buprenorphine to avoid withdrawal symptoms. Buprenorphine Withdrawal Symptoms Include: Nausea; Headaches; Pain; Flushing; Dizziness; Overdose of Buprenorphine is extremely rare but can occur if mixed with anti-depressants, alcohol, benzodiazepines, GHB and other central nervous system drugs.