Pharmacokinetics of lidocaine and bupivacaine in retrobulbar and facial block

Abstract

Analgesia can be obtained during ophthalmic surgery by regional anesthesia using local anesthetic agents. As in other indications, neurological complications may occur, especially because the site of injection is close to the central nervous system. In order to evaluate the risk of retrobulbar and facial block obtained after 40 mg lidocaine and 20 mg bupivacaine injection, pharmacokinetics of both drugs was evaluated in plasma obtained from 11 patients. In addition, 3 cerebrospinal fluid samples were analyzed. Maximal plasma concentration was 0.73 +/- 0.33 micrograms.ml-1 for lidocaine and 0.19 +/- 0.06 micrograms.ml-1 for bupivacaine, obtained 24.7 +/- 23.0 min and 12.0 +/- 3.7 min after the end of injection, respectively. CSF/plasma ratio was in the range 0.05-0.26 for lidocaine and 0.56-1.33 for bupivacaine. In all patients, regional anesthesia was sufficient to perform surgery without any other analgesic drug. No sign of cardiovascular or respiratory toxicity was observed during the study.