Extradural administration of bupivacaine: pharmacokinetics and metabolism in pregnant and non-pregnant women.
We found a similar time (about 0.4 h) to maximum serum concentration after extradural administration of bupivacaine 1.78 (SD 0.27) mg kg-1 to six pregnant patients at term, 1.58 (0.13) mg kg-1 to six women younger than 65 yr and 1.50 mg kg-1 to six women older than 65 yr. There were no significant differences in terminal half-life. No unconjugated 4'-hydroxy-bupivacaine was detected in the serum and urine of pregnant patients, in contrast with the other groups. The pregnant patients had significantly greater serum concentrations of the N-dealkylated metabolite, N-desbutyl-bupivacaine (DBB), than the non-pregnant groups. In contrast with 4'-hydroxy-bupivacaine, no conjugated forms of bupivacaine and desbutyl-bupivacaine were detected in urine. The mean total urinary excretion of bupivacaine and its metabolites and their conjugates varied between 2.46 and 3.22% of the total dose administered in the three patient groups, indicating that both 4'-hydroxylation and N-dealkylation are minor metabolic pathways in man.
Pihlajamäki
K
K
Department of Pharmacology, University of Turku, Finland.
Kanto
J
J
Lindberg
R
R
Karanko
M
M
Kiilholma
P
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000767:Anesthesia, Epidural; D000773:Anesthesia, Obstetrical; D002045:Bupivacaine / Q000031:analogs & derivatives / Q000378:metabolism* / Q000493:pharmacokinetics; D002585:Cesarean Section; D005260:Female; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy / Q000378:metabolism*
C025149:2',6'-pipecoloxylidide; D002045:Bupivacaine