title: Evaluation of a sustained-release formulation of buprenorphine for analgesia in rats.
abstract: Preventing and minimizing pain in laboratory animals is a basic tenet of biomedical research and is warranted for ethical, legal, and scientific reasons. Postoperative analgesia is an important facet of pain management. A sustained-release formulation of buprenorphine was tested in rats for analgesic efficacy and plasma concentration over a 72-h time period. Rats were injected subcutaneously with either 1.2 mg/kg sustained-release formulation (Bup-SR), 0.2 mL/kg buprenorphine HCl (Bup-HCl), or an equivalent volume of sustained-release vehicle and tested in a thermal nociception model or a surgical postoperative pain model. In both models, Bup-SR showed evidence of providing analgesia for 2 to 3 d. Thermal latency response in rats that received the sustained-release formulation increased 28.4% and 15.6% compared with baseline values on days 1 and 2, respectively. Rats with a unicortical tibial defect and treated with Bup-SR showed similar willingness to bear weight on the hindlimbs as did negative-control animals (no surgery), demonstrated by counting vertical raises; rats treated with Bup-HCl had significantly fewer vertical raises than did control rats for 5 d after surgery. Plasma concentrations of buprenorphine remained over 1 ng/mL for 72 h after a single dose of Bup-SR. Taken together, the results indicate that this formulation of buprenorphine may be a viable option for treating postsurgical pain in laboratory rats.
authors: Office of Animal Welfare, University of Virginia, Charlottesville, Virginia, USA. plf6z@virginia.edu
authors: Patricia L
authors: PL
authors: Foley
authors: Haixiang
authors: H
authors: Liang
authors: Andrew R
authors: AR
authors: Crichlow
mesh_terms: D000698:Analgesia / Q000379:methods / Q000662:veterinary*; D000701:Analgesics, Opioid / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D002047:Buprenorphine / Q000097:blood / Q000494:pharmacology*; D003692:Delayed-Action Preparations / Q000494:pharmacology; D004338:Drug Combinations; D007279:Injections, Subcutaneous / Q000662:veterinary; D008297:Male; D010147:Pain Measurement / Q000662:veterinary*; D010149:Postoperative Pain / Q000188:drug therapy / Q000662:veterinary*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000701:Analgesics, Opioid; D003692:Delayed-Action Preparations; D004338:Drug Combinations; D002047:Buprenorphine