Anaesthetic efficacy of bupivacaine 2-hydroxypropyl-beta-cyclodextrin for dental anaesthesia after inferior alveolar nerve block in rats

Bupivacaine is a long-acting local anaesthetic that is widely used in medicine and dentistry. The duration and intensity of its sensory blockade in animal models is increased by its inclusion in complexes with cyclodextrins. The aim of the present study was to evaluate the anaesthetic efficacy of bupivacaine 2-hydroxypropyl-beta-cyclodextrin (HP beta CD) inclusion complex for dental anaesthesia after inferior alveolar nerve block in rats. Thirty rats were each given an injection close to the mandibular foramen of 0.2 ml of one of the following formulations: 0.5% bupivacaine alone; 0.5% bupivacaine with 1:200,000 epinephrine; and 0.5% bupivacaine-HP beta CD inclusion complex (bupivacaine-HP beta CD). The other sides were used as controls, with either 0.9% saline or anaesthetic-free HP beta CD solution being injected. The onset, success, and duration of pulpal anaesthesia were assessed by electrical stimulation ("pulp tester") on inferior molars. Results were analysed using ANOVA (Tukey), log rank, and chi square tests (alpha = 5%). There were no differences among the formulations in onset of anaesthesia (p = 0.59) or between the bupivacaine plus epinephrine and bupivacaine plus HP beta CD in duration of anaesthesia, but bupivacaine plus epinephrine gave significantly higher values than bupivacaine alone (p = 0.007). Bupivacaine plus epinephrine was a better anaesthetic than bupivacaine alone (p = 0.02), while Bupi-HP beta CD gave intermediate results, and therefore did not differ significantly from the other 2 groups (p = 0.18 with bupivacaine alone; and p = 0.44 with bupivacaine plus epinephrine). The bupivacaine-HP beta CD complex showed similar anaesthetic properties to those of bupivacaine with epinephrine. (C) 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.52545245