Plasma Concentrations of Different Local
Anesthetics After Facial Nerve Block


Franz Schimek, Dietrich Friess and Manfred Fahle


BACKGROUND AND OBJECTIVE
The authors studied the plasma concentrations of several anesthetics to determine the relative safety of facial blocks as reflected by each anesthetic's kinetics.

PATIENTS AND METHODS
Seventyfive patients undergoing cataract extraction received a proximal block of the facial nerve using prilocaine, lidocaine, mepivacaine, bupivacaine, or etidocaine.

RESULTS
Mean plasma concentrations were significantly lower after the administration of prilocaine than they were after the administration of lidocaine and mepivacaine (P < 0.0008; multivariate analysis of variance, Roy's max root). Plasma concentrations of lidocaine and mepivacaine or bupivacaine and etidocaine did not differ from each other. Mean plasma concentrations of prilocaine, lidocaine, and mepivacaine increased continuously for 15 to 22 minutes, whereas mean plasma concentrations of bupivacaine and etidocaine peaked after 10 and 9 minutes, respectively. Peak plasma concentrations of anesthetics were well below toxic levels in all patients.

CONCLUSIONS
Although systemic toxicity resulting from the rapid absorption of local anesthetics after facial nerve block seems unlikely, prilocaine may be the anesthetic most preferred for such a block because of its high level of safety.