Pain Updates: Butrans - Buprenorphine patch

• is a transdermal system (buprenorphine) indicated for moderate-to-severe chronic pain in patients requiring an around-the-clock opioid analgesic for an extended period of time.
• exerts its analgesic effect via high affinity binding to μ opiate receptors in the CNS; displays partial mu agonist and weak kappa antagonist activity
• intended to be used for the continual release of buprenorphine transdermally over a 7-day period per patch, for the management of persistent pain of moderate intensity. BuTrans can be used in either opioid naïve patients or patients previously treated with PRN (as needed) analgesics when the analgesic requirement has progressed to a need for continuous opioid analgesia.
• Pallimed article: http://www.pallimed.org/2008/07/td-buprenorphine-for-everything-and.html
• From: http://www.palliativedrugs.com/buprenorphine.html
• Its release is controlled by the physical characteristics of the matrix and is proportional to the surface area of the patch. Absorption of the buprenorphine through the skin and into the systemic circulation is influenced by the stratum corneum and blood flow.
• There are few practical differences in the use of the buprenorphine or fentanyl matrix patches.
• Compared with fentanyl, TD buprenorphine adheres better. However, after patch removal, it is associated with more persistent erythema (± localized pruritus), and sometimes a more definite dermatitis.
• Retrospective analysis suggests that, compared with TD fentanyl, patients receiving TD buprenorphine (as Transtec®) have a slower rate of dose increase and longer periods of dose stability.
• Buprenorphine does slow intestinal transit, but possibly less so than morphine. Constipation may be less severe.
• In contrast to other opioids, buprenorphine does not suppress the gonadal axis or testosterone levels.
• Compared with morphine and other opioids, buprenorphine has little or no immunosuppressive effect.
• With typical clinical doses, it is possible to use morphine (or other μ-opioid receptor agonist) for break-through (episodic) pain and to switch either way between buprenorphine and morphine (or other μ-opioid receptor agonist) without loss of analgesia.
• Despite concerns that antagonism could occur, this is likely only with a very large dose; even with buprenorphine 32mg SL, only 84% of μ-opioid receptors are occupied.
• A recent study in volunteers suggests that buprenorphine may have an antihyperalgesic effect as well as an analgesic effect.
• Animal studies and case reports also suggest that buprenorphine may be of particular benefit in neuropathic pain. The implications for the clinical management of neuropathic pain, if any, need to be determined by controlled studies.