Pharmacokinetics and pharmacodynamics of local analgesia for laparoscopic tubal ligations.

The pharmacokinetics and pharmacodynamics of lidocaine and bupivacaine, when used for laparoscopic sterilization under local anesthesia, are described in 21 patients. Under direct vision with the use of a laparoscope, local anesthetic solution was sprayed onto the fallopian tubes. Nine patients were administered 12 ml of lidocaine 2% (240 mg), and 12 patients received 20 ml of bupivacaine 0.5% (100 mg). Samples of venous blood were drawn at 0, 5, 10, 15, 20, 30, 60, and 120 minutes after the intraperitoneal placement of local anesthetic. Drug assays were performed by means of gas chromatography. The peak concentration of lidocaine was detected within 30 minutes. The mean concentration was 1.70 +/- 0.34 micrograms/mg (range, 1.19 to 2.07 micrograms/ml; convulsive level, 18 to 26 micrograms/ml). The peak concentration of bupivacaine was not evident until 60 minutes after injection. The mean concentration was 0.44 +/- 0.15 micrograms/ml (range, 0.20 to 0.77 micrograms/ml; convulsive level, 4.5 to 5.5 micrograms/ml). These findings may justify the use of larger volumes of these local anesthetics for more painful diagnostic laparoscopies whenever adhesions and/or extensive manipulation is anticipated.