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Stereoselectivity in the placental transfer and kinetic disposition of racemic bupivacaine administered to parturients with or without a vasoconstrictor
Author(s) -
Papini Olga,
Do Carmo Silva Mathes Ângelo,
Pereira Da Cunha Sergio,
Lucia Lanchote Vera
Publication year - 2003
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.10308
Subject(s) - bupivacaine , stereoselectivity , chemistry , anesthesia , ephedrine , epinephrine , medicine , biochemistry , catalysis
Abstract The aim of the present study was to investigate the stereoselectivity in the kinetic disposition and the transplacental distribution of bupivacaine in term parturients during labor. Maternal age ranged from 18–37 years and fetal gestational age from 37.6–41.5 weeks. Healthy parturients (n = 23) received epidural 0.5% racemic bupivacaine alone (group A) or combined with epinephrine (group B). Maternal venous blood was sampled at regular intervals until 8 h after drug administration and umbilical venous blood was obtained at delivery. Bupivacaine enantiomers were determined in plasma samples by HPLC using a Chiralcel® OD‐R column and a UV detector. One‐ or two‐compartment models were fitted to data and differences between the (+)‐(R) and (–)‐(S) enantiomers were compared with the paired Wilcoxon test ( P < 0.05). The influence of epinephrine was evaluated using the unpaired Mann‐Whitney test ( P < 0.05). The disposition of bupivacaine in maternal plasma was stereoselective, with higher V d/f (140.60 vs. 132.81 L for group A and 197.86 vs. 169.46 L for group B) and C l/f (29.00 vs. 25.43 L/h for group A and 33.15 vs. 26.39 L/h for group B) and lower t 1/2 β (3.24 vs. 3.30 h for group A and 4.36 vs. 4.45 h for group B) being observed for (+)‐(R)‐bupivacaine. The combined administration of epinephrine resulted in higher V d/f (197.86 vs. 140.60 L for (+)‐(R) and 169.46 vs. 132.81 L for (–)‐(S)) and t 1/2 β values (4.36 vs. 3.24 h for (+)‐(R) and 4.45 vs. 3.30 h for (–)‐(S)). The transplacental distribution of bupivacaine was stereoselective only when bupivacaine was administered without epinephrine (group B), with a higher cord blood/maternal blood ratio being observed for (–)‐(S)‐bupivacaine (0.40 vs. 0.35). Chirality 16:65–71, 2004 . © 2004 Wiley‐Liss, Inc.