buprenorfine

Buprenorphine, commonly spelled buprenorphine (some sources spell it buprenorfine), is a semi-synthetic opioid used primarily to treat opioid use disorder and, in some formulations, chronic pain. It is a partial agonist at the mu-opioid receptor and an antagonist at the kappa-opioid receptor, with high affinity for mu receptors. This combination provides withdrawal relief and analgesia while producing a ceiling effect on respiratory depression, reducing overdose risk compared with full opioid agonists.

In opioid use disorder, buprenorphine is used as medication-assisted treatment to suppress withdrawal and decrease illicit opioid use. It is typically prescribed as sublingual tablets or films, often in combination with naloxone to deter injection misuse. Other formulations include transdermal patches for chronic pain and long-acting implants for maintenance in selected patients.

Mechanism-wise, the drug’s partial mu-agonist activity delivers analgesia and withdrawal control but with a ceiling effect on euphoria and respiratory suppression at higher doses. Buprenorphine’s high receptor affinity also contributes to its ability to block the effects of other opioids.

Pharmacokinetics generally involve sublingual administration with relatively slow onset and long duration, due to tight receptor binding and slow dissociation. It is extensively metabolized by the liver and has a long elimination half-life, allowing once-daily dosing in many regimens. Dosing and formulation can affect onset and total exposure, especially in patients with hepatic impairment.

Safety and regulation: Buprenorphine can cause drowsiness, constipation, and nausea. It carries risks of misuse, dependence, and withdrawal; concurrent central nervous system depressants increase the risk of respiratory depression. It is used in pregnancy for opioid dependence when indicated, though neonatal abstinence syndrome can occur. It is a controlled substance in many jurisdictions with prescribing requirements to limit diversion.