Serum lidocaine concentrations following subcutaneous administration

Serum lidocaine concentrations were determined following subcutaneous administration for local anesthesia in the management of lacerations in the emergency room setting. Thirty patients received doses of lidocaine hydrochloride 1% solution ranging from 10 to 300 mg. Venous blood samples were drawn 15, 30, 45, and 60 minutes after lidocaine administration. Serum lidocaine determinations were made using an immunoassay system and verified by gas chromatography. There was no evidence of lidocaine absorption from the subcutaneous injection sites. There were no detectable concentrations of lidocaine in any of the patient blood samples. The absorption characteristics of subcutaneously administered lidocaine appear to be altered in traumatized tissue.