Key result
Epidural administration of bupivacaine with epinephrine increased the volume of distribution and half-life for both enantiomers compared to bupivacaine alone.
Why the study?
Does the addition of epinephrine to epidural bupivacaine alter its stereoselective kinetic disposition and transplacental distribution in term parturients?
Does the addition of epinephrine to epidural bupivacaine alter its stereoselective kinetic disposition and transplacental distribution in term parturients?
The disposition of bupivacaine in maternal plasma is stereoselective, and the addition of epinephrine alters its volume of distribution and half-life.
Epinephrine may alter bupivacaine kinetics in parturients; leaves open effects on stereoselective transplacental distribution and neonatal outcomes.
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(R) 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)beta (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)beta 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.
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Papini et al. (2003) studied Healthy term parturients during labor (n=23). Epidural 0.5% racemic bupivacaine combined with epinephrine vs. Epidural 0.5% racemic bupivacaine alone was evaluated on Stereoselectivity in the kinetic disposition and transplacental distribution of bupivacaine. Epidural administration of bupivacaine with epinephrine increased the volume of distribution and half-life for both enantiomers compared to bupivacaine alone.
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