Bupivacaine and buprenorphine: Potential dynamic duo in veterinary dental nerve blocks
Bupivacaine regional nerve blocks are commonly used to provide short- to medium-term analgesia in veterinary dentistry. Because human research has shown that adding buprenorphine to a nerve block can increase the analgesia duration threefold, the practice is becoming more popular in veterinary medicine. But until this study, its effectiveness in animals had not been formally investigated.
Eight healthy adult beagles with a calculus stage of 0-1 and a gingivitis index of 0-1 were enrolled in the study. Using dental dolorimetry, a previously proven model of inducing pain through electrical conduction, the researchers were able to determine the baseline minimum alveolar concentration (MAC) for noxious stimulation of the right maxillary canine tooth. Next, each dog received a maxillary nerve block treatment on two separate occasions. One nerve block used bupivacaine alone, and the second block used a mixture of bupivacaine and buprenorphine. After every treatment, the researchers determined each dog’s MAC and calculated its difference from the normal MAC. This continued on a daily basis until each participant’s MAC matched the original baseline value.
The duration of analgesia for both bupivacaine alone and bupivacaine plus buprenorphine was longer than expected. With bupivacaine alone, all eight dogs showed significant MAC sparing effects for a duration of 24 hours. In some dogs, the effects lasted 72 hours. With both bupivacaine and buprenorphine, significant MAC sparing effects lasted for 48 hours in all dogs and 96 hours in some. Two of the eight dogs continued to demonstrate MAC sparing effects with the dual block at 96 hours but were not tested further.
Take home points
Both bupivacaine alone and a bupivacaine plus buprenorphine mix are effective at providing regional nerve blocks in veterinary dentistry, and the study suggests that the durations of analgesia for both blocks are likely significantly longer than previously suspected. The extended duration of the bupivacaine plus buprenorphine block was particularly interesting since 25% of the dogs saw an analgesia duration of at least four days. Because of the small sample size, the differences between the two regional blocks were not proven to be statistically significant. The study’s researchers estimate that 40 dogs would be needed for the results to be statistically significant.
Link to abstract: http://jov.sagepub.com/content/33/2/90.abstract
Snyder LB, Snyder CJ, Hetzel S. Effects of buprenorphine added to bupivacaine infraorbital nerve blocks on isoflurane minimum alveolar concentration using a model for acute dental/oral surgical pain in dogs. J Vet Dent 2016;33(2):90-96.