buprenorphin

Buprenorphin, commonly spelled buprenorphine, is a semi-synthetic opioid used both as a medication for opioid use disorder and as an analgesic for chronic pain. It is a partial agonist at the mu-opioid receptor and an antagonist at the kappa-opioid receptor, with very high receptor affinity. This combination produces analgesia and helps relieve withdrawal and cravings while offering a ceiling effect on respiratory depression, which contributes to a wider safety margin than full opioid agonists.

In the treatment of opioid use disorder, buprenorphin is used for maintenance therapy and to manage withdrawal symptoms. It is commonly supplied as sublingual tablets or films, sometimes combined with naloxone (for example, formulations marketed as buprenorphine/naloxone) to deter injection. For pain management, buprenorphin is available in various formulations, including transdermal patches and buccal or sublingual products, tailored to the indication and patient needs.

Pharmacokinetics and administration vary by formulation. Sublingual administration bypasses much of the first-pass metabolism, allowing relatively rapid onset with a long duration of action. Buprenorphin is mainly metabolized by hepatic enzymes, particularly CYP3A4, to active and inactive metabolites and is excreted in urine and feces. The drug’s high receptor affinity means it can displace other opioids and may precipitate withdrawal in individuals currently dependent on full agonists.

Common safety considerations include drowsiness, nausea, constipation, and dizziness. Caution is advised when used with other central nervous system depressants, including benzodiazepines and alcohol. Buprenorphin is a controlled substance in many countries and is typically prescribed within specialized treatment programs or under medical supervision.