Duration of action of sustained-release buprenorphine in 2 strains of mice.

Buprenorphine HCl is a common analgesic for laboratory mice undergoing surgical procedures. The documented duration of action of buprenorphine HCl is as short as 3 to 5 h in mice, potentially necessitating readministration for continued analgesia. A long-acting buprenorphine formulation would reduce handling-associated stress and provide uninterrupted analgesia. This study used the hot-plate assay to assess the antinociceptive effects of a single injection of sustained-release buprenorphine (bup-SR), buprenorphine-HCl (bup-HCl), and saline over 72 h in young adult male BALB/cJ and SWR/J mice. SWR/J mice had shorter baseline latencies than did BALB/cJ mice, possibly reflecting greater sensitivity to thermal nociception. Relative increase from baseline latency (% maximal possible effect) was significant for buprenorphine-SR at 2, 6, and 12 h compared with saline. According to results from a hot-plate assay, the analgesic efficacy of buprenorphine-SR appears to last at least 12 h in male BALB/cJ and SWR/J mice.