Buprenorphine is a semi-synthetic derivative of thebaine, one of the most chemically reactive opium alkaloids. Buprenorphine has a molecular weight of 467 and its structure is typically opioid with the inclusion of a C-7 side-chain containing a t-butyl group. This group confers overall lipophilicity on the molecule which has an important influence on its pharmacology. Opioids exert their pharmacological effects by binding to opioid receptors. The pharmacological effects are determined by the nature of opioid-receptor interaction. Some of these effects such as analgesia, mediated by an agonistic action at the μ-opioid receptor are desirable, whereas others such as nausea, sedation, or constipation can be considered as unwanted adverse effects. Buprenorphine is a μ-opioid receptor agonist with high affinity, but low intrinsic activity.
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