Comparative Evaluation of Efficacy and Safety on 2% Lidocaine with Various Concentrations of Epinephrine

Abstract

Despite safe and efficient use of local anesthesia is essential in dentistry, the optimal concentration of epinephrine contained in 2% lidocaine has not been established. Currently, 2% lidocaine containing 1:100,000 and 1:80,000 of epinephrine are widely used in clinical treatment. Some studies reported that high concentration of epinephrine in anesthetics might cause cardiovascular risk. In this study, the changes of blood pressure and heart rate, anesthetic and hemostatic effect after injection of 2% lidocaine containing various concentrations of epinephrine were evaluated in rats and mice to find out an appropriate concentration of epinephrine in anesthetic mixture: 2% lidocaine without epinephrine (L0), 2% lidocaine with 1:200,000 epinephrine (L200), 2% epinephrine with 1:100,000 epinephrine (L100), and 2% epinephrine with 1:80,000 epinephrine (L80). The changes of mean arterial pressure (MAP) and the heart rate after administration of the anesthetic mixture were monitored and calculated using a physiologic recording system in rats. Duration of local anesthetic effect was evaluated by pricking the hind paw of the mouse. A spectrophotometric hemoglobin assay was used to objectively quantify hemostatic effect of anesthetic mixture. The MAP was increased in a dose-dependent manner in response to epinephrine. L0 and L200 showed relatively consistent in MAP, while MAP in L100 and L80 were slightly elevated. The MAP of L80 showed significant increase in comparison with that of L0. The heart rate was relatively decreased in L0, and increased in L80. The hemodynamic responses about the changes of MAP and heart rate resulted in relatively consistent in L200. The onset of action was shorter than one min in all groups. In the presence of epinephrine (L200, L100, and L80), the action duration and hemostatic effect of local anesthetics were significantly improved compared with L0. In conclusion, L200 is as effective as L100 or L80, and may be recommended in patients with cardiovascular disease and in elderly patients susceptible to epinephrine.