[Pharmacokinetics of articaine in mandibular nerve block]

Up to now, mandibular nerve blocks have been carried out without knowing the exact blood concentrations resulting from the use of the local anesthetics. Due to the high vascularity a rapid increase in serum local anesthetic levels is to be expected. Due to analytical problems, the literature provides controversial statements about the pharmacokinetics of articaine which is generally used for this block. The given half-life periods following intramuscular application range from 39 min [8] to 31 h [6]. For this reason, mandibular nerve blocks with 2 ml 4% articaine with 1:200,000 epinephrine were carried out in 10 awake patients and 10 patients during intubation anesthesia. RESULTS. Blood samples from peripheral veins showed an average maximum concentration of 2.1 +/- 1.3 mg/l after 12.5 +/- 2.5 min. After 8 h the value had fallen below the minimum detection limit of 0.05 mg/l. In the present study, a half-life of approximately 20 min was determined for articaine after conduction anesthesia. This local anesthetic holds an exceptional position because as an amide-type local anesthetic it contains an additional ester group that is hydrolytically metabolized in the blood. The concentration of the resulting metabolite reaches a maximum value of 2.6 +/- 1.6 mg/l after 40 to 50 min. CONCLUSIONS. Compared to other amide-type local anesthetics, whose terminal plasma half-life varies between 1 and 3.6 h [5], the value of 20 min found for articaine is very low. This is in part due to its structure, as the ester group is rapidly metabolized by plasma esterases. Because of its rapid breakdown articaine is very suitable for use in oral surgery. The HPLC method represents an uncomplicated analytical technique for the determination of local anesthetics levels in blood and other body fluids.