Buprenorphine

Abstract

Properties, Metabolism and Forms Buprenorphine is a semi-synthetic derivate of thebaine. [1] Buprenorphine has both analgesic and antihyperalgesic systemic effects [2-4] but the exact mechanism of the different modalities remains unknown. [5] It has three known receptor binding mechanisms. First Buprenorphine is an ?-opioid receptor agonist. Secondly Buprenorphine shows partial agonistic activity at the opioid receptor-like receptor 1 (ORL1)-receptor that induces a pronociceptive effect, for example useful in the treatment of hyperalgesia. Its antagonistic activity at the third receptor, the ?-opioid receptor, might explain the less sedative and psychomimetic effects compared to morphine or fentanyl. Buprenorphine is metabolised by the liver into norbuprenorphine. The latter is a μ-opioid, δ-opioid and nociception receptor full agonist, as well as a κ-opioid receptor partial agonist. [6, 7] After glucuronidation, both glucuronides are eliminated mainly through excretion into the bile. [8] Anaesthesiological Clinical Use A higher-dose sublingual form (up to 2 mg) is indicated for detoxification and long-term replacement therapy in opioid dependency. [9-14] It is also a good alternative to sustained-release opioids such as morphine and oxycodone. [15, 16]. The transdermal form is indicated for the treatment of severe cancer pain and severe non-cancer pain not responding to non-opioids. [17] But also in orthopaedic surgery e.g., in elderly, it is proven an effective tool for pain control [18-20]. The intravenous formulation is used in continuous postoperative pain treatment. Regional Administration of Buprenorphine Conflicting results have been published on the efficacy and duration of various opioids (including buprenorphine) in prolonging the duration of local anaesthetics. [21, 22]. The regional use of buprenorphine has been described in neuraxial [23] and peripheral blocks as adjuvants. [21, 22]. Local buprenorphine application, e.g., to the stellate ganglion, is also described in chronical pain management. [24] Other Clinical Use Buprenorphine can be sleep-inducing which can be an advantage when pain is accompanied with sleeplessness. [25] Other clinical indications are pregnancy [26], maxillofacial surgery [27], treatment in non-suicidal selfinjury [28], vasectomy surgery [29], and due the euphoria and anxiolytic effects it can be used as an alternative antidepressant in patients with depression due to pain. Adverse Effects and Contraindications The adverse effects are similar to those of other opioids. The most important side effect is nausea and vomiting, in particular when initiated at high doses. Another important side- effect is respiratory depression but due to a relatively long half-life, this depression is characterised by a ceiling effect. [30] The combination with alcohol and/or benzodiazepines however, can lead to fatal respiratory depression. A "precipitated withdrawal" is described when buprenorphine is used in persons with a physically dependency for full-agonist opioids, who are not already in withdrawal. [31-33] Conclusion Buprenorphine is a common used opioid that provide effective pain relief in cancer and Non-Cancer patients. As an adjuvant used in regional anesthesia, it is likely to? prolong the peripheral nerve block duration.