Buprenorphine + norbuprenorphine

Buprenorphine + norbuprenorphine refers to the presence of both buprenorphine, a semi-synthetic opioid, and its major active metabolite, norbuprenorphine. Buprenorphine is primarily used for opioid use disorder and pain management. It acts as a partial agonist at the mu-opioid receptor, an antagonist at the kappa-opioid receptor, and an agonist at the nociceptin receptor. This unique pharmacology results in effective suppression of withdrawal symptoms with a lower risk of respiratory depression compared to full agonists[5][6][8]. Norbuprenorphine is formed via N-dealkylation by CYP3A4 metabolism of buprenorphine and is itself an active metabolite. Unlike buprenorphine, norbuprenorphine is a full agonist at mu-, delta-, and nociceptin receptors but has much less antinociceptive potency while causing more pronounced respiratory depression due to poor brain penetration[1][6][8]. Both compounds are further glucuronidated before excretion.