Stability of local anesthetics in heparinized blood, plasma and sulfuric acid.

Abstract

This study was undertaken to investigate the stability of local anesthetics in different media. 60 patients with axillary plexus block, using prilocaine, mepivacaine or lidocaine 1%, or with lumbar epidural catheter-anesthesia, using bupivacaine 0.5%, were investigated. Stability was evaluated in heparinized whole blood for 24 h at +4 degrees C, in plasma for 8 week at -25 degrees C and in sulfuric acid for 6 months at -25 degrees C. Mean recovery rates were between 96.4% and 102.6% in all local anesthetics and media. No statistical significance became obvious for differences between recovery rates and initial values. Stability of prilocaine, mepivacaine, lidocaine and bupivacaine can be expected when samples are stored as heparinized whole blood for 24 h at +4 degrees C, plasma for 8 weeks at -25 degrees C, and after preparation into sulfuric acid for 6 months at -25 degrees C.