title: Voluntary Running-Wheel Activity, Arterial Blood Gases, and Thermal Antinociception in Rats after 3 Buprenorphine Formulations.
abstract: Buprenorphine HCl (BUP) is a μ-opioid agonist used in laboratory rodents. New formulations of buprenorphine (for example, sustained-released buprenorphine [BUP SR], extended-release buprenorphine [BUP ER]) have been developed to extend the analgesic duration. In a crossover design, 8 adult rats were injected subcutaneously with either BUP, BUP SR, BUP ER, or saline, after which voluntary running-wheel activity, arterial blood gases, and thermal withdrawal latency were assessed. Wheel running was decreased at 24 h compared with baseline in all treatment groups but returned to baseline by 48 h. Arterial pH, HCO3(-), and CO2 were not changed between groups or over time. However, arterial oxygen was lower than baseline in the BUP (-8 ± 2 mm Hg), BUP SR (-7 ± 1 mm Hg), and BUP ER (-17 ± 2 mm Hg) groups compared with saline controls (3 ± 2 mm Hg); the BUP ER group showed the greatest decrease when all time points were combined. BUP increased the withdrawal latency at 1 h (15% ± 3%), whereas BUP ER increased latencies at 4, 8, 12, and 48 h (35% ± 11%, 21% ± 7%, 26% ± 7%, and 22% ± 9%, respectively) and BUP SR prolonged latencies at 24, 48, and 72 h (15% ± 6%, 18% ± 5%, and 20% ± 8%, respectively). The duration of thermal analgesia varied between buprenorphine formulations, but all 3 formulations reduced voluntary-running activity at 24 h after injection and might cause hypoxemia in normal adult rats.
authors.affiliation: Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA. rebecca.johnson@wisc.edu.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Johnson
mesh_terms: D000698:Analgesia; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000818:Animals; D001784:Blood Gas Analysis; D002047:Buprenorphine / Q000008:administration & dosage*; D018592:Cross-Over Studies; D008297:Male; D008991:Monitoring, Physiologic; D010146:Pain / Q000188:drug therapy / Q000662:veterinary*; D010147:Pain Measurement; D051381:Rats; D012420:Running
chemical_list: D000701:Analgesics, Opioid; D002047:Buprenorphine