Comparison of the analgesic efficacy of oral ABT-116 administration with that of transmucosal buprenorphine administration in dogs

Objective: To evaluate the analgesic efficacy of ABT-116, a transient receptor potential cation channel vanilloid subfamily V member 1 antagonist, and compare it with that of buprenorphine by measurement of mechanical and thermal nociceptive thresholds in dogs.

Animals: Six 7- to 8-month-old dogs (3 males and 3 females).

Procedures: In a crossover study design, all dogs received ABT-116 (30 mg/kg, PO) and buprenorphine (0.03 mg/kg, orotransmucosally), with each treatment separated by 1 week. Physiologic variables were recorded prior to and 1, 6, and 24 hours after drug administration. Thermal (thoracic) and mechanical (dorsolateral aspect of the radius [proximal] and dorsopalmar aspect of the forefoot [distal]) nociceptive thresholds were assessed prior to (baseline) and 15 minutes and 1, 2, 4, 6, 12, 18, and 24 hours after treatment.

Results: Buprenorphine administration resulted in higher overall thermal and proximal mechanical nociceptive thresholds, compared with ABT-116. Distal mechanical nociceptive thresholds after treatment were higher than baseline values for both treatments, but the magnitude of change was greater for buprenorphine at 1 hour after administration. Whereas HR and RR sporadically differed from baseline values after ABT-116 administration, rectal temperature increased from a baseline value of 39 ± 0.2°C (mean ± SD) to a peak of 40.6 ± 0.2°C at 6 hours.

Conclusions and clinical relevance: In dogs without inflammation or nerve injury, PO administration of ABT-116 did not consistently result in an increase in nociceptive thresholds. However, clinically relevant increases in rectal temperature were identified after ABT-116 administration.