Buprenorphine

buprenorphine is a semisynthetic opioid of the morphinan chemical class. it functions as a mixed partial agonist opioid receptor modulator.

at higher dosages, it is used to treat opioid addiction in opioid-dependent individuals. in lower dosages it is used to control moderate-acute pain in non-opioid-tolerant individuals and in even lower dosages it is used to control moderate chronic pain.

chemistry

buprenorphine is a semi-synthetic morphinan derivative of the opioid alkaloid thebaine. like many opioids, such as codeine or hydrocodone, it is has a morphinan backbone.

buprenorphine and other molecules of this class contain a polycyclic core of three benzene rings fused in a zig-zag pattern called phenanthrene. a fourth nitrogen containing ring is fused to the phenanthrene at r₉ and r₁₃. buprenophine (along with other morphinans) contains an ether bridge between two of its rings, connecting the benzene and opposite cyclohexane ring through an oxygen group.

buprenorphine is unique to human medical opioids as it contains an addition fused ring which connects to the lower cyclohexane ring at r₆ and r₁₄. this structure is called a endoethenotetrahydrooripavine backbone, often found in veterinarian opioids. it contains a hydroxy group (oh-) substituted on the benzene ring and a methoxy group bound to the lower cyclohexane ring. the backbone of buprenorphine is also substituted with a methyl cyclopropyl moeity on its amino group. adjacent to its methoxy attachment, the cyclohexane ring is bonded to r₂ of a 2-butanol chain.

pharmacology

buprenorphine acts as a partial agonist of the μ-opioid receptor with a binding affinity of k~i~ = 1.5 nm; it also acts as an antagonist of the κ-opioid receptor with a binding affinity of k~i~ = 2.5 nm and the δ-opioid receptor with a binding affinity of k~i~ = 6.1 nm.

buprenorphine exerts its effects by binding to and activating the μ-opioid receptor. this occurs because opioids structurally mimic endogenous endorphins which are naturally found within the body and also work upon the μ-opioid receptor set. the way in which opioids structurally mimic these natural endorphins results in their euphoria, pain relief and anxiolytic effects. this is because endorphins are responsible for reducing pain, causing sleepiness, and feelings of pleasure. they can be released in response to pain, strenuous exercise, orgasm, or general excitement.