[Serum level determination of local anesthetics using high pressure liquid chromatography]

We report a high resolution liquid chromatography method for simultaneous determination of lidocaine, mepivacaine and bupivacaine in serum using cyclicine as a standard. Drugs are extracted from serum using dichloromethane in an alkaline medium type columns in a mobile phase with 0.1 M phosphate buffer at pH 7.5, methanol and acetonitrile (33:17:50) were used for separation. Spectrophotometric measurement was performed at 207 nm. In a concentration ranging from 0.5 to 8 micrograms/ml, r values of 0.997, 0.989 and 0.998 were obtained for lidocaine, mepivacaine and bupivacaine, respectively. The coefficient of variation estimated at 2 micrograms/ml was 2, 19, 2.76 and 2.48%, respectively. A maximal error of 4.5%, 3.6% and 2.9% found for "inter day" repeated measurement at the above concentration for each drug. Thus, high sensitivity, reproducibility and relative simpleness of the method are demonstrated for its clinical use in determination of serum levels of local anesthetics.