Efficacy of bupivacaine 2-hydroxypropyl-β-cyclodextrin in rat’s inferior alveolar nerve block

Objective: To compare the anesthetic efficacy of 0.5% bupivacaine in 2-hydroxypropyl β-cyclodextrin with commercial bupivacaine formulations, by using an inferior alveolar nerve block (IANB) in rats. Methods: 30 rats received an injection of 0.2mL of one of the following formulations: 0.5% bupivacaine (Bupi); a commercial 0.5% bupivacaine with 1:200.000 epinephrine (Bupi-Epi) solutions; and 0.5% bupivacaine in 2-hydroxypropyl-β-cyclodextrin (Bupi-HPβCD). The injections were performed randomly in one side of mandible and the contralateral side received 0.2 mL of 0.9% NaCl (control) or anesthetic free 2-hydroxypropyl-β-cyclodextrin (HPβCD) formulation. The onset and duration of pulpal anesthesia were assessed by electrical stimulation (“pulp tester”). Results: None statistically significant differences (ANOVA, p>0.05) were observed among the formulations (mean±SEM) concerning IANB onset (Bupi=3.3±0.58min; Bupi-Epi=3.1±0.89min; Bupi-HPβCD=3.6±0.65min). Bupi (56.0±6.5min) presented lower anesthesia duration (ANOVA, p<0.05) when compared to both Bupi-Epi (85.0±8.7min) and Bupi-HPβCD (69.5±8.1min), and no differences were observed between these two solutions (p>0.05). Bupi-Epi presented higher anesthesia success than Bupi-HPβCD and Bupi (p<0.05). Bupi-HPβCD showed higher success than Bupi (p<0.05). Conclusion: the complexation in HPβCD or the addition of epinephrine increased the anesthesia performance of 0.5% bupivacaine. Apoio: FAPESP - 2009/11820-3