Buprenorphine
Buprenorphine is a partial opioid agonist and also an opioid antagonist. It came out as an analgesic in the 1980s, but is nowadays used also for the treatment of opioid addiction. It is sold under trade names such as Temgesic, Buprenex, Subutex and Suboxone (combined with naloxone).
Mode of action
Buprenorphine is a thebaine derivative, and its analgesic effect is due to agonism of μ subtype of opioid receptor. Buprenorphine is also a κ- antagonist. Unlike other opioids, naloxone can only partially revert the effects of buprenorphine. Buprenophine has quite a long effect, 48 hours, due to its slow dissociation from the opioid receptors. Patients build tolerance towards buprenorphine fairly quickly.
Pharmacokinetics
Buprenorphine is administered as hydrochloride as either intramuscular or intravenous injection or as sublingual tablets. It is not administered orally, due to very high first-pass metabolism. Burenorphine is metabolised in the liver into an active metabolite, norbuprenorphine by N-dealkylation via CYP-3A4. The metabolites are further conjugated with glucuronic acid and eliminated mainly through excretion into the bile. See Instant Detox and The Bitter Pill from Wired magazine.
Side effects
Most common side effects are drowsiness, nausea, sweating and dizziness. High doses can also cause respiratory depression, which can be dangerous, for there is no dependable antagonist. Buprenorphine causes addiction, but mainly psychological dependence. There is debate as to whether Buprenorphine has the potential to cause liver damage in some patients. Due to the potential threat of developing jaundice of the liver, it is recommended that doctors refrain from prescribing this synthetic opiod to any patient suffering from liver or kidney problems.
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