Comparative efficacy and pharmacokinetics of racemic bupivacaine and S-bupivacaine in third molar surgery.
OBJECTIVE
To compare the efficacy and pharmacokinetics of racemic bupivacaine (rac-bupivacaine) with S-bupivacaine as primary local anesthetic agent in bilateral impacted third molar extractions.


METHODS
A randomised, double blind, two period cross-over design was employed. Six subjects (2 males, 4 females; age 19-25 years; weight 69.2+/-9.4 kg) received bupivacaine hydrochloride injection (6.6 ml) as rac-bupivacaine (0.5% as salt) or S-bupivacaine (0.5% as base) prior to extraction of impacted third molars on one side and three weeks later on the other side. Anesthesia, blood loss associated with surgery and post-operative pain experience were evaluated. Plasma samples were analysed for bupivacaine enantiomers by chiral HPLC.


RESULTS
In 7/12 operations, anesthesia adequate for surgery was delayed (>10 min) or unsatisfactory requiring lidocaine rescue medication. Despite this, there were no significant differences in onset and duration of anesthesia, blood loss or post-operative pain experience between the two arms of the study. Pharmacokinetic parameters were not significantly different and there was no evidence of chiral inversion after dosing with S-bupivacaine.


CONCLUSIONS
Both study drugs were inadequate as single anesthetic agent for third molar surgery. Any decision to use S-bupivacaine for oral surgery must rest on evidence that it is less toxic than the racemic drug.
School of Pharmacy, University of Otago, Dunedin, New Zealand. paul.fawcett@stonebow.otago.ac.nz
J P
JP
Fawcett
J M
JM
Kennedy
A
A
Kumar
R
R
Ledger
G M
GM
Kumara
M J
MJ
Patel
M
M
Zacharias
D000328:Adult; D000772:Anesthesia, Local; D000779:Anesthetics, Local / Q000737:chemistry / Q000493:pharmacokinetics*; D019540:Area Under Curve; D002045:Bupivacaine / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008964:Molar, Third / Q000601:surgery*; D013237:Stereoisomerism; D014081:Tooth Extraction
D000779:Anesthetics, Local; D002045:Bupivacaine