20.03.5.4 Buprenorphine

Morphine stimulates opioid m-receptors to induce analgesia. Another effect mediated by opioid m-receptors is respiratory depression. Respiratory depression is a common side effect associated with full agonists at opioid m-receptors (e.g. morphine)

Buprenorphine is a partial agonist at opioid m-receptors. Buprenorphine causes analgesia but is unlikely to cause excessive respiratory depression.

Buprenorphine is relatively well absorbed from most routes. It can be used sublingually for rapid relief of pain in post-operative patients. Buprenorphine is a slowly dissociating agonist, which means it sticks to the receptors. When the buprenorphine is associated with the receptors, it is not in the plasma. Thus, the plasma levels of buprenorphine can be very low but buprenorphine is still having an effect, as it is bound to receptors.

Buprenorphine is used as an analgesic. Buprenorphine is also used in opioid addiction, where it can be used to stabilise the addict prior to a gradual reduction of dose.