2009-03-28T09:30:03Z 2011-03-11T08:57:20Z http://cogprints.org/id/eprint/6399 This item is in the repository with the URL: http://cogprints.org/id/eprint/6399 2009-03-28T09:30:03Z

We evaluated the commonly prescribed analgesic buprenorphine in a postoperative pain model in rats, assessing acute postoperative pain relief, rebound hyperalgesia, and the long-term effects of postoperative opioid treatment on subsequent opioid exposure. Rats received surgery (paw incision under isoflurane anesthesia), sham surgery (anesthesia only), or neither and were treated postoperatively with 1 of several doses of subcutaneous buprenorphine. Pain sensitivity to noxious and nonnoxious mechanical stimuli at the site of injury (primary pain) was assessed at 1, 4, 24, and 72 h after surgery. Pain sensitivity at a site distal to the injury (secondary pain) was assessed at 24 and 72 h after surgery. Rats were tested for their sensitivity to the analgesic and locomotor effects of morphine 9 to 10 d after surgery. Buprenorphine at 0.05 mg/kg SC was determined to be the most effective; this dose induced isoalgesia during the acute postoperative period and the longest period of pain relief, and it did not induce longterm changes in opioid sensitivity in 2 functional measures of the opioid system. A lower dose of buprenorphine (0.01 mg/kg SC) did not meet the criterion for isoalgesia, and a higher dose (0.1 mg/kg SC) was less effective in pain relief at later recovery periods and induced a long-lasting opioid tolerance, indicating greater neural adaptations. These results support the use of 0.05 mg/kg SC buprenorphine as the upper dose limit for effective treatment of postoperative pain in rats and suggest that higher doses produce long-term effects on opioid sensitivity.

Dr. Leslie I. Curtin licurtin@buffalo.edu Julie A. Grakowsky jg96@buffalo.edu Mauricio Suarez msuarez@ria.buffalo.edu Dr. Alexis C. Thompson athompso@ria.buffalo.edu Dr. Jean M. DiPirro dipirrjm@buffalostate.edu Dr. Lisa B.E. Martin lbmartin@buffalo.edu Dr. Mark B. Kristal kristal@buffalo.edu